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<title>Sensors and Sensor Boards</title>
-<meta name="author" content="David Gay, Phil Levis, Wei Hong, Joe Polastre, and Gilman Tolle" />
+<meta name="author" content="David Gay, Philip Levis, Wei Hong, Joe Polastre, and Gilman Tolle" />
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<tr class="field"><th class="docinfo-name">Type:</th><td class="field-body">Documentary</td>
</tr>
<tr><th class="docinfo-name">Status:</th>
-<td>Draft</td></tr>
+<td>Final</td></tr>
<tr class="field"><th class="docinfo-name">TinyOS-Version:</th><td class="field-body">2.x</td>
</tr>
<tr><th class="docinfo-name">Author:</th>
-<td>David Gay, Phil Levis, Wei Hong, Joe Polastre, and Gilman Tolle</td></tr>
-<tr class="field"><th class="docinfo-name">Draft-Created:</th><td class="field-body">10-Jun-2006</td>
-</tr>
-<tr class="field"><th class="docinfo-name">Draft-Discuss:</th><td class="field-body">TinyOS Developer List <tinyos-devel at mail.millennium.berkeley.edu></td>
-</tr>
+<td>David Gay, Philip Levis, Wei Hong, Joe Polastre, and Gilman Tolle</td></tr>
</tbody>
</table>
<div class="note">
<h1><a id="principles" name="principles">1. Principles</a></h1>
<p>This section describes the basic organization principles for sensor
drivers in TinyOS.</p>
-<p>For background, a sensor may be attached to the microcontroller on a
+<p>For background, a sensor can be attached to the microcontroller on a
TinyOS platform through a few different types of connections:</p>
<blockquote>
<ul class="simple">
<li>Connected through a standard digital bus protocol (1-Wire, I2C, SPI)</li>
</ul>
</blockquote>
-<p>Physically, these connections may also be decoupled by attaching the
+<p>Physically, these connections can also be decoupled by attaching the
sensors to a <cite>sensor board</cite>, which can be removed from the TinyOS
-platform, and may fit multiple different TinyOS platforms.</p>
+platform, and could attach to multiple different TinyOS platforms.</p>
<p>The capabilities of a physical sensor are made available to a TinyOS
application through a <cite>sensor driver</cite>.</p>
-<p>According to the HAA <a class="citation-reference" href="#tep2" id="id1" name="id1">[TEP2]</a>, TinyOS devices should provide both
+<p>According to the HAA <a class="citation-reference" href="#tep2" id="id1" name="id1">[TEP2]</a>, TinyOS devices SHOULD provide both
simple hardware-independent interfaces for common-case use (HIL) and
rich hardware-dependent interfaces for special-case use (HAL). Sensor
-drivers should follow this spirit as well.</p>
+drivers SHOULD follow this spirit as well.</p>
<p>TinyOS 2.x represents each sensor as an individual component. This
allows the compilation process to minimize the amount of code
-included. A sensor board containing multiple sensors should be
+included. A sensor board containing multiple sensors SHOULD be
represented as a collection of components, one for each sensor,
contained within a sensor board directory.</p>
-<p>Sensors, being physical devices that may be shared, can benefit from
+<p>Sensors, being physical devices that can be shared, can benefit from
virtualization and arbitration. This document describes a design
-pattern for sensor virtualization that may be followed by sensor
+pattern for sensor virtualization that SHOULD be followed by sensor
drivers.</p>
-<p>The same physical sensor may be attached to multiple different TinyOS
+<p>The same physical sensor can be attached to multiple different TinyOS
platforms, through platform-dependent interconnections. The common
-logic of sensor driver should be factored into chip-dependent,
-platform-independent components, and those components should be bound
+logic of sensor driver SHOULD be factored into chip-dependent,
+platform-independent components, and those components SHOULD be bound
to the hardware resources on a platform by platform-dependent
components, and to the hardware resources on a sensor board by
sensorboard-dependent components.</p>
<p>A physical sensor has a general class and a specific set of
performance characteristics, captured by the make and model of the
-sensor itself. The naming of the sensor driver components should
-reflect the specifc name of the sensor, and optionally provide a
-component with a generic name for application authors who only care
-about the general class of the sensor.</p>
-<p>This document assumes that sensors return uninterpreted values of
-arbitrary size or datatype. Conversion of sensor values to something
-with actual physical meaning is beyond the scope of this document.</p>
+sensor itself. The naming of the sensor driver components SHOULD
+reflect the specifc name of the sensor, and MAY provide a component
+with a generic name for application authors who only care about the
+general class of the sensor.</p>
+<p>This document requires that sensor components specify the range (in
+bits) of values returned by sensor drivers, but takes no position on
+the meaning of these values. They MAY be raw uninterpreted values or
+they MAY have some physical meaning. If a driver returns uninterpreted
+values, the driver MAY provide additional interfaces that would allow
+higher-level clients to obtain information (e.g. calibration
+coefficients) needed to properly interpret the value.</p>
</div>
<div class="section">
<h1><a id="sensor-hil-components" name="sensor-hil-components">2. Sensor HIL Components</a></h1>
access to the sensor. A sensor device driver can provide such
virtualization for itself by defining a nesC generic client
component. When a client component is being used, a call to a
-top-level SID interface should be delayed when the device is busy,
-rather than failing. This virtualization may be easier to accomplish
-by using one of the arbiters provided by the system.</p>
+top-level SID interface SHOULD be delayed when the device is busy,
+rather than failing. Using one of the system arbiters can make the
+implementation of this requirement easier to accomplish.</p>
<p>For example:</p>
<pre class="literal-block">
generic configuration SensirionSht11C() {
provides interface Read<uint16_t> as Temperature;
provides interface ReadStream<uint16_t> as TemperatureStream;
+ provides interface DeviceMetadata as TemperatureDeviceMetadata;
+
provides interface Read<uint16_t> as Humidity;
provides interface ReadStream<uint16_t> as HumidityStream;
+ provides interface DeviceMetadata as HumidityDeviceMetadata;
}
implementation {
// connect to the ADC HIL, GPIO HAL, or sensor's HAL
MAY be started once at boot time by wiring to the <cite>MainC.Boot</cite>
interface. Sensors that draw appreciable power MUST be started in
response to a call to one of the top-level SID interfaces, and stopped
-some time after that call completes. One of the power-management
-components described in <a class="citation-reference" href="#tep115" id="id4" name="id4">[TEP115]</a> may be useful for this purpose.</p>
+some time after that call completes. Using one of the power-management
+components described in <a class="citation-reference" href="#tep115" id="id4" name="id4">[TEP115]</a> can make this implementation easier.</p>
<p>Generally, simple types are made up of octets. However, sensor values
-often have levels of precision besides a multiple of 8. A device MAY
-specify the precision of one of its interfaces with the DeviceMetadata
-interface:</p>
+often have levels of precision besides a multiple of 8. To account for
+such cases, each device MUST specify the precision of each one of its
+interfaces by providing the DeviceMetadata interface:</p>
<pre class="literal-block">
interface DeviceMetadata {
command uint8_t getSignificantBits();
}
</pre>
-<p>The name of the instance of DeviceMetadata SHOULD clearly indicate
-which interface it corresponds to.</p>
-<p>A value contained returned from the device through a SID interface
-MAY be left shifted so that it covers as much of the type's range as
-possible. For example, if a 12-bit ADC reading is presented as a
-16-bit Read interface:</p>
-<pre class="literal-block">
-component DemoSensorC {
- provides interface Read<uint16_t>;
-}
-</pre>
-<p>then the driver MAY shift the 12-bit value left so that its range is
-0x0000 - 0xfff0, rather than 0x0000 - 0x0fff.</p>
+<p>The name of the instance of DeviceMetadata MUST clearly indicate which
+interface it corresponds to.</p>
+<p>The getSignificantBits() call MUST return the number of significant
+bits in the reading. For example, a sensor reading taken from a 12-bit
+ADC would typically return the value 12 (it might return less if, e.g.,
+physical constraints limit the maximum A/D result to 10-bits).</p>
<p>Sensor driver components SHOULD be named according to the make and
model of the sensing device being presented. Using specific names
gives the developer the option to bind to a particular sensor, which
author, to support application developers who are only concerned with
the particular type of the sensor and not its make, model, or detailed
performance characteristics.</p>
-<p>A "common" naming layer atop a HIL may look like this:</p>
+<p>A "common" naming layer atop a HIL might look like this:</p>
<pre class="literal-block">
generic configuration TemperatureC() {
provides interface Read<uint16_t>;
provides interface ReadStream<uint16_t>;
+ provides interface DeviceMetadata;
}
implementation {
components new SensirionSht11C();
Read = SensirionSht11C.Temperature;
ReadStream = SensirionSht11C.TemperatureStream;
+ DeviceMetadata = SensirionSht11C.TemperatureDeviceMetadata;
}
generic configuration HumidityC() {
provides interface Read<uint16_t>;
provides interface ReadStream<uint16_t>;
+ provides interface DeviceMetadata;
}
implementation {
components new SensirionSht11C();
Read = SensirionSht11C.Humidity;
ReadStream = SensirionSht11C.HumidityStream;
+ DeviceMetadata = SensirionSht11C.HumidityDeviceMetadata;
}
</pre>
</div>
<li>A <cite>StdControl</cite> or <cite>SplitControl</cite> interface for manual power
management by the user, following the conventions described in
<a class="citation-reference" href="#tep115" id="id5" name="id5">[TEP115]</a>.</li>
-<li>A Resource[] interface for requesting access to the device and
-possibly performing automated power management.</li>
-<li>Any other interfaces needed to control the device.</li>
+<li>A <cite>Resource</cite> interface for requesting access to the device and
+possibly performing automated power management, following
+the conventions described in <a class="citation-reference" href="#tep108" id="id6" name="id6">[TEP108]</a> and <a class="citation-reference" href="#tep115" id="id7" name="id7">[TEP115]</a>.</li>
+<li>Any other interfaces needed to control the device, e.g., to
+read or write calibration coefficients.</li>
</ul>
<p>For example:</p>
<pre class="literal-block">
</pre>
</div>
<div class="section">
-<h1><a id="sensor-hpl-components" name="sensor-hpl-components">4. Sensor HPL Components</a></h1>
-<p>A sensor HPL is necessarily platform-dependent or
-sensorboard-dependent. These components should provide access to the
-physical resources needed by the sensor, in a platform-independent
-manner that can be used by the shared logic of the sensor HAL
-components. In the case of bus-based sensors, this HPL may be nothing
-more than wiring to the appropriate bus interface for use by the HAL
-component.</p>
-<p>For example:</p>
+<h1><a id="sensor-component-organization-and-compiler-interaction-guidelines" name="sensor-component-organization-and-compiler-interaction-guidelines">4. Sensor Component Organization and Compiler Interaction Guidelines</a></h1>
+<p>Sensors are associated either with a particular sensor board or with a
+particular platform. Both sensors and sensor boards MUST have unique
+names. Case is significant, but two sensor (or sensor board) names
+MUST differ in more than case. This is necessary to support platforms
+where filename case differences are not significant.</p>
+<p>Each sensor board MUST have its own directory whose name is the sensor
+board's unique name (referred to as <sensorboard> in the rest of this
+section). Default TinyOS 2.x sensor boards are placed in
+<tt class="docutils literal"><span class="pre">tos/sensorboards/<sensorboard></span></tt>, but sensor board directories can be
+placed anywhere as long as the nesC compiler receives a <tt class="docutils literal"><span class="pre">-I</span></tt> directive
+pointing to the sensor board's directory. Each sensor board directory
+MUST contain a <tt class="docutils literal"><span class="pre">.sensor</span></tt> file (described below). If the
+sensor board wishes to define any C types or constants, it SHOULD
+place these in a file named <tt class="docutils literal"><span class="pre"><sensorboard>.h</span></tt> in the sensor board's
+directory.</p>
+<p>A sensor board MAY contain components that override the default TinyOS
+<em>demo sensors</em>. This allows the sensor board to easily be used with
+TinyOS sample applications that use the demo sensors. If a sensor
+board wishes to override the default demo sensor:</p>
+<ul>
+<li><p class="first">It MUST provide a generic component named <tt class="docutils literal"><span class="pre">DemoSensorC</span></tt> with the
+following signature:</p>
<pre class="literal-block">
-configuration HplSensirionSht11C {
- provides interface Init;
- provides interface Resource[ uint8_t id ];
- provides interface GeneralIO as DATA;
- provides interface GeneralIO as SCK;
- provides interface GpioInterrupt as InterruptDATA;
-}
-implementation {
- // connect to platform or sensorboard-dependent resources
- // power-manage the sensor through platform-specific means
-}
+provides interface Read<uint16_t>;
+provides interface DeviceMetadata;
+</pre>
+</li>
+<li><p class="first">It MAY provide a generic component named <tt class="docutils literal"><span class="pre">DemoSensorNowC</span></tt> with the
+following signature:</p>
+<pre class="literal-block">
+provides interface ReadNow<uint16_t>;
+provides interface DeviceMetadata;
+</pre>
+<p>This component SHOULD sample the same sensor as <tt class="docutils literal"><span class="pre">DemoSensorC</span></tt>.</p>
+</li>
+<li><p class="first">It MAY provide a generic component named <tt class="docutils literal"><span class="pre">DemoSensorStreamC</span></tt> with the
+following signature:</p>
+<pre class="literal-block">
+provides interface ReadStream<uint16_t>;
+provides interface DeviceMetadata;
</pre>
+<p>This component SHOULD sample the same sensor as <tt class="docutils literal"><span class="pre">DemoSensorC</span></tt>.</p>
+</li>
+</ul>
+<p>These components MUST be an alias for one of the sensor board's usual
+sensors, though they change the precision of the sensor if necessary.
+For instance, if <tt class="docutils literal"><span class="pre">DemoSensorC</span></tt> is an alias for a 20-bit sensor that
+provides a <tt class="docutils literal"><span class="pre">Read<uint32_t></span></tt> interface, <tt class="docutils literal"><span class="pre">DemoSensorC</span></tt> would still
+provide <tt class="docutils literal"><span class="pre">Read<uint16_t></span></tt> and would include code to reduce the
+precision of the aliased sensor.</p>
+<div class="section">
+<h2><a id="compiler-interaction" name="compiler-interaction">4.1 Compiler Interaction</a></h2>
+<p>When the <tt class="docutils literal"><span class="pre">ncc</span></tt> nesC compiler frontend is passed a <tt class="docutils literal"><span class="pre">-board=X</span></tt> option,
+it executes the <tt class="docutils literal"><span class="pre">.sensor</span></tt> file found in the sensor board directory
+<tt class="docutils literal"><span class="pre">X</span></tt>. This file is a perl script which can add or modify any
+compile-time options necessary for the sensor board. It MAY modify the
+following perl variables, and MUST NOT modify any others:</p>
+<ul class="simple">
+<li><tt class="docutils literal"><span class="pre">@includes</span></tt>: This array contains the TinyOS search path, i.e., the
+directories which will be passed to nescc (the TinyOS-agnostic nesC
+compiler) as <tt class="docutils literal"><span class="pre">-I</span></tt> arguments. You MUST add to <tt class="docutils literal"><span class="pre">@includes</span></tt> any
+directories needed to compile this sensor board's components. For
+instance, if your sensor boards depends on support code found in
+<tt class="docutils literal"><span class="pre">tos/chips/sht11</span></tt>, you would add <tt class="docutils literal"><span class="pre">"%T/chips/sht11"</span></tt> to <tt class="docutils literal"><span class="pre">@includes</span></tt>.</li>
+<li><tt class="docutils literal"><span class="pre">@new_args</span></tt>: This is the array of arguments which will be passed to
+nescc. You MUST add any arguments other than <tt class="docutils literal"><span class="pre">-I</span></tt> that are necessary
+to compile your sensor board components to <tt class="docutils literal"><span class="pre">@new_args</span></tt>.</li>
+</ul>
+<p>If a sensor is associated with a platform <cite>P</cite> rather than a sensor
+board, then that platform MUST ensure that, when compiling for
+platform <cite>P</cite>, all directories needed to compile that sensor's
+component are added to the TinyOS search path (see <a class="citation-reference" href="#tep131" id="id8" name="id8">[TEP131]</a> for
+information on how to set up a TinyOS platform).</p>
</div>
<div class="section">
-<h1><a id="directory-organization-guidelines" name="directory-organization-guidelines">5. Directory Organization Guidelines</a></h1>
-<p>Because the same physical sensor may be attached to TinyOS platforms
-in many different ways, the organization of sensor drivers should
-reflect the distinction between sensor and sensor interconnect.</p>
-<p>Sensor components commonly exist at three levels:
-platform-independent, sensorboard-dependent, and
-platform-dependent. Factoring a sensor driver into these three pieces
-allows for greater code reuse when the same sensor is attached to
-different sensorboards or platforms.</p>
-<p>Platform-independent sensor driver components for a particular sensor,
-like protocol logic, when in the core TinyOS 2.x source tree, SHOULD
-be placed into "tos/chips/<sensor>", where <sensor> reflects the make
-and model of the sensor device being supported. When not a part of the
-core source tree, this directory can be placed anywhere as long as the
-nesC compiler recieves a <cite>-I</cite> directive pointing to the sensor's
-directory. However, not all sensors have a sufficiently large amount
-of platform-independent logic to justify a separate "chips"
-directory. Sensor chips are more likely to be digital sensors than
-analog sensors, for example.</p>
-<p>A sensor board is a collection of sensor components with a fixed name,
-intended for attachment to multiple platforms. Each sensor board MUST
-have its own directory named <sensorboard>. Default TinyOS 2.x sensor
-boards are placed in "tos/sensorboards/<sensorboard>", but sensor
-board directories can be placed anywhere as long as the nesC compiler
-receives a <cite>-I</cite> directive pointing to the sensor board's directory.</p>
-<p>Both sensors and sensor boards MUST have unique names. Case is
-significant, but two sensor boards MUST differ in more than case. This
-is necessary to support platforms where filename case differences are
-not significant.</p>
-<p>Each sensor board directory MUST contain a <cite>.sensor</cite> file. This file
-is a perl script which gets executed as part of the <cite>ncc</cite> nesC
-compiler frontend. It can add or modify any compile-time options
-necessary for a particular sensor board. It MAY modify the following
-perl variables, and MUST NOT modify any others:</p>
+<h2><a id="sensor-components" name="sensor-components">4.2 Sensor Components</a></h2>
+<p>A particular sensor is typically supported by many components,
+including the HIL and HAL components from Sections 2 and 3, A/D
+conversion components (for analog sensors), digital bus components
+(e.g., SPI, for digital sensors), system services (timers, resource
+and power management, ...), glue components (to connect sensors,
+sensor boards and platforms), etc. These components can be divided
+into three classes: sensorboard-dependent, platform-dependent and
+platform-independent. The sensorboard and platform MUST ensure
+(Section 4.1) that all these components can be found at compile-time.</p>
+<p>Because the same physical sensor can be used on many platforms or
+sensor boards, and attached in many different ways, to maximize code
+reuse the organization of sensor drivers SHOULD reflect the
+distinction between sensor and sensor interconnect. The sensor
+components SHOULD be platform-independent, while the sensor
+interconnect components are typically sensorboard or
+platform-dependent. However, some sensors (e.g. analong sensors) will
+not have a sufficiently large amount of platform-independent logic to
+justify creating platform-independent components.</p>
+<p>The following guidelines specify how to organize sensor and sensor
+interconnect components within TinyOS's directory hierarchy. These
+guidelines are only relevant to components that are part of the core
+source tree. The string <tt class="docutils literal"><span class="pre"><sensor></span></tt> SHOULD reflect the make and model
+of the sensor device.</p>
<ul class="simple">
-<li>@new_args: This is the array of arguments which will be passed to
-nescc. For instance, you might add an include directive to @new_args
-with push @new_args, <cite>-Isomedir</cite>. This could be used to include
-subdirectories.</li>
-<li>@commonboards: This can be set to a list of sensor board names which
-should be added to the include path list. These sensor boards must be
-in tinyos-2.x/tos/sensorboards.</li>
+<li>Platform-independent sensor components that exist as part of a
+larger chip, like a MCU internal voltage sensor, SHOULD be placed in
+a subdirectory of the chip's directory
+<tt class="docutils literal"><span class="pre">tos/<chip>/sensors/<sensor></span></tt>.</li>
+<li>Other platform-independent sensor components SHOULD be placed
+in <tt class="docutils literal"><span class="pre">tos/chips/<sensor></span></tt>.</li>
+<li>Sensorboard-dependent sensor and sensor interconnect components
+SHOULD be placed either in the <tt class="docutils literal"><span class="pre"><sensorboard></span></tt> directory or in a
+<tt class="docutils literal"><span class="pre"><sensorboard>/chips/<sensor></span></tt> directory.</li>
+<li>Platform-dependent sensor and sensor interconnect components SHOULD
+be placed in <tt class="docutils literal"><span class="pre">tos/<platform>/chips/<sensor></span></tt>.</li>
</ul>
-<p>If the sensor board wishes to define any C types or constants, it
-SHOULD place these in a file named <sensorboard>.h in the sensor
-board's directory.</p>
-<p>A sensor board directory MAY contain a "chips" directory, with
-subdirectories for each of the sensors connected to the sensor board.
-If a "chips" subdirectory is used, sensorboard-dependent driver
-components needed to connect platform-independent logic to a
-particular attachment for that sensor should be placed in
-"<sensorboard>/chips/<sensor>".</p>
-<p>Components needed to connect the platform-independent sensor driver
-components or sensorboard-dependent components to the hardware
-resources available on a particular platform SHOULD be placed in
-"tos/<platform>/chips/<sensor>". In addition, components for a sensor
-that only exists on a particular platform should be placed in a such a
-directory.</p>
-<p>Sensors that exist as part of a larger chip, like a MCU internal
-voltage sensor, SHOULD be placed in a subdirectory of the chip's
-directory. "tos/<chip>/sensors/<sensor>".</p>
-<p>The <cite>.platform</cite> and <cite>.sensor</cite> files need to include enough <cite>-I</cite>
-directives to locate all of the necessary components needed to support
-the sensors on a platform and/or sensorboard.</p>
-<p>All of these directory organization guidelines are only intended for
-code that will enter the core source tree. In general, sensor
-components may be placed anywhere as long as the nesC compiler
-receives enough <cite>-I</cite> directives to locate all of the necessary pieces.</p>
+</div>
</div>
<div class="section">
-<h1><a id="authors-addresses" name="authors-addresses">6. Authors' Addresses</a></h1>
+<h1><a id="authors-addresses" name="authors-addresses">5. Authors' Addresses</a></h1>
<div class="line-block">
<div class="line">David Gay</div>
<div class="line">2150 Shattuck Ave, Suite 1300</div>
</div>
</div>
<div class="section">
-<h1><a id="citations" name="citations">7. Citations</a></h1>
+<h1><a id="citations" name="citations">6. Citations</a></h1>
<table class="docutils citation" frame="void" id="tep2" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id1" name="tep2">[TEP2]</a></td><td>TEP 2: Hardware Abstraction Architecture</td></tr>
</tbody>
</table>
+<table class="docutils citation" frame="void" id="tep108" rules="none">
+<colgroup><col class="label" /><col /></colgroup>
+<tbody valign="top">
+<tr><td class="label"><a class="fn-backref" href="#id6" name="tep108">[TEP108]</a></td><td>TEP 108: Resource Arbitration</td></tr>
+</tbody>
+</table>
<table class="docutils citation" frame="void" id="tep114" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<table class="docutils citation" frame="void" id="tep115" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
-<tr><td class="label"><a name="tep115">[TEP115]</a></td><td><em>(<a class="fn-backref" href="#id4">1</a>, <a class="fn-backref" href="#id5">2</a>)</em> TEP 115: Power Management of Non-Virtualized Devices</td></tr>
+<tr><td class="label"><a name="tep115">[TEP115]</a></td><td><em>(<a class="fn-backref" href="#id4">1</a>, <a class="fn-backref" href="#id5">2</a>, <a class="fn-backref" href="#id7">3</a>)</em> TEP 115: Power Management of Non-Virtualized Devices</td></tr>
+</tbody>
+</table>
+<table class="docutils citation" frame="void" id="tep131" rules="none">
+<colgroup><col class="label" /><col /></colgroup>
+<tbody valign="top">
+<tr><td class="label"><a class="fn-backref" href="#id8" name="tep131">[TEP131]</a></td><td>TEP 131: Creating a New Platform for TinyOS 2.x</td></tr>
</tbody>
</table>
</div>
+<div class="section">
+<h1><a id="appendix-a-sensor-driver-examples" name="appendix-a-sensor-driver-examples">Appendix A: Sensor Driver Examples</a></h1>
+<div class="section">
+<h2><a id="analog-adc-connected-sensor" name="analog-adc-connected-sensor">1. Analog ADC-Connected Sensor</a></h2>
+<p>The Analog sensor requires two components</p>
+<ul class="simple">
+<li>a component to present the sensor itself (HamamatsuS1087ParC)</li>
+<li>a component to select the appropriate hardware resources, such as
+ADC port 4, reference voltage 1.5V, and a slow sample and hold time
+(HamamatsuS1087ParP).</li>
+</ul>
+<p>The AdcReadClientC component and underlying machinery handles all of
+the arbitration and access to the ADC.</p>
+<pre class="literal-block">
+tos/platforms/telosa/chips/s1087/HamamatsuS1087ParC.nc
+
+// HIL for the HamamatsuS1087 analog photodiode sensor
+generic configuration HamamatsuS1087ParC() {
+ provides interface Read<uint16_t>;
+ provides interface ReadStream<uint16_t>;
+ provides interface DeviceMetadata;
+}
+implementation {
+ // Create a new A/D client and connect it to the Hamamatsu S1087 A/D
+ // parameters
+ components new AdcReadClientC();
+ Read = AdcReadClientC;
+
+ components new AdcReadStreamClientC();
+ ReadStream = AdcReadStreamClientC;
+
+ components HamamatsuS1087ParP;
+ DeviceMetadata = HamamatsuS1087ParP;
+ AdcReadClientC.AdcConfigure -> HamamatsuS1087ParP;
+ AdcReadStreamClientC.AdcConfigure -> HamamatsuS1087ParP;
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/chips/s1087/HamamatsuS1087ParP.nc
+
+#include "Msp430Adc12.h"
+
+// A/D parameters for the Hamamatsu - see the MSP430 A/D converter manual,
+// Hamamatsu specification, Telos hardware schematic and TinyOS MSP430
+// A/D converter component specifications for the explanation of these
+// parameters
+module HamamatsuS1087ParP {
+ provides interface AdcConfigure<const msp430adc12_channel_config_t*>;
+ provides interface DeviceMetadata;
+}
+implementation {
+ msp430adc12_channel_config_t config = {
+ inch: INPUT_CHANNEL_A4,
+ sref: REFERENCE_VREFplus_AVss,
+ ref2_5v: REFVOLT_LEVEL_1_5,
+ adc12ssel: SHT_SOURCE_ACLK,
+ adc12div: SHT_CLOCK_DIV_1,
+ sht: SAMPLE_HOLD_4_CYCLES,
+ sampcon_ssel: SAMPCON_SOURCE_SMCLK,
+ sampcon_id: SAMPCON_CLOCK_DIV_1
+ };
+
+ async command const msp430adc12_channel_config_t* AdcConfigure.getConfiguration() {
+ return &config;
+ }
+
+ command uint8_t DeviceMetadata.getSignificantBits() { return 12; }
+}
+</pre>
+</div>
+<div class="section">
+<h2><a id="binary-pin-connected-sensor" name="binary-pin-connected-sensor">2. Binary Pin-Connected Sensor</a></h2>
+<p>The Binary sensor gets a bit more complex, because it has three
+components:</p>
+<ul class="simple">
+<li>one to present the sensor (UserButtonC)</li>
+<li>one to execute the driver logic (UserButtonLogicP)</li>
+<li>one to select the appropriate hardware resources, such as MSP430
+Port 27 (HplUserButtonC).</li>
+</ul>
+<p>Note that the presentation of this sensor is not arbitrated because
+none of the operations are split-phase.</p>
+<pre class="literal-block">
+tos/platforms/telosa/UserButtonC.nc
+
+// HIL for the user button sensor on Telos-family motes
+configuration UserButtonC {
+ provides interface Get<bool>; // Get button status
+ provides interface Notify<bool>; // Get button-press notifications
+ provides interface DeviceMetadata;
+}
+implementation {
+
+ // Simply connect the button logic to the button HPL
+ components UserButtonLogicP;
+ Get = UserButtonLogicP;
+ Notify = UserButtonLogicP;
+ DeviceMetadata = UserButtonLogicP;
+
+ components HplUserButtonC;
+ UserButtonLogicP.GpioInterrupt -> HplUserButtonC.GpioInterrupt;
+ UserButtonLogicP.GeneralIO -> HplUserButtonC.GeneralIO;
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/UserButtonLogicP.nc
+
+// Transform the low-level (GeneralIO and GpioInterrupt) interface to the
+// button to high-level SID interfaces
+module UserButtonLogicP {
+ provides interface Get<bool>;
+ provides interface Notify<bool>;
+ provides interface DeviceMetadata;
+
+ uses interface GeneralIO;
+ uses interface GpioInterrupt;
+}
+implementation {
+ norace bool m_pinHigh;
+
+ task void sendEvent();
+
+ command bool Get.get() { return call GeneralIO.get(); }
+
+ command error_t Notify.enable() {
+ call GeneralIO.makeInput();
+
+ // If the pin is high, we need to trigger on falling edge interrupt, and
+ // vice-versa
+ if ( call GeneralIO.get() ) {
+ m_pinHigh = TRUE;
+ return call GpioInterrupt.enableFallingEdge();
+ } else {
+ m_pinHigh = FALSE;
+ return call GpioInterrupt.enableRisingEdge();
+ }
+ }
+
+ command error_t Notify.disable() {
+ return call GpioInterrupt.disable();
+ }
+
+ // Button changed, signal user (in a task) and update interrupt detection
+ async event void GpioInterrupt.fired() {
+ call GpioInterrupt.disable();
+
+ m_pinHigh = !m_pinHigh;
+
+ post sendEvent();
+ }
+
+ task void sendEvent() {
+ bool pinHigh;
+ pinHigh = m_pinHigh;
+
+ signal Notify.notify( pinHigh );
+
+ if ( pinHigh ) {
+ call GpioInterrupt.enableFallingEdge();
+ } else {
+ call GpioInterrupt.enableRisingEdge();
+ }
+ }
+
+ command uint8_t DeviceMetadata.getSignificantBits() { return 1; }
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/HplUserButtonC.nc
+
+// HPL for the user button sensor on Telos-family motes - just provides
+// access to the I/O and interrupt control for the pin to which the
+// button is connected
+configuration HplUserButtonC {
+ provides interface GeneralIO;
+ provides interface GpioInterrupt;
+}
+implementation {
+
+ components HplMsp430GeneralIOC as GeneralIOC;
+
+ components new Msp430GpioC() as UserButtonC;
+ UserButtonC -> GeneralIOC.Port27;
+ GeneralIO = UserButtonC;
+
+ components HplMsp430InterruptC as InterruptC;
+
+ components new Msp430InterruptC() as InterruptUserButtonC;
+ InterruptUserButtonC.HplInterrupt -> InterruptC.Port27;
+ GpioInterrupt = InterruptUserButtonC.Interrupt;
+}
+</pre>
+</div>
+<div class="section">
+<h2><a id="digital-bus-connected-sensor" name="digital-bus-connected-sensor">3. Digital Bus-Connected Sensor</a></h2>
+<p>The Digital sensor is the most complex out of the set, and includes
+six components:</p>
+<ul class="simple">
+<li>one to present the sensor (SensirionSht11C)</li>
+<li>one to request arbitrated access and to transform the sensor HAL
+into the sensor HIL (SensirionSht11P)</li>
+<li>one to present the sensor HAL (HalSensirionSht11C)</li>
+<li>one to perform the driver logic needed to support the HAL, which
+twiddles pins according to a sensor-specific protocol
+(SensirionSht11LogicP).</li>
+<li>one to select the appropriate hardware resources, such as the clock,
+data, and power pins, and to provide an arbiter for the sensor
+(HplSensirionSht11C).</li>
+<li>one to perform the power control logic needed to support the power
+manager associated with the arbiter (HplSensirionSht11P).</li>
+</ul>
+<p>This bus-connected sensor is overly complex because it does not rely
+on a shared framework of bus manipulation components. A sensor built
+on top of the I2C or SPI bus would likely require fewer components.</p>
+<pre class="literal-block">
+tos/platforms/telosa/chips/sht11/SensirionSht11C.nc
+
+// HIL interface to Sensirion SHT11 temperature and humidity sensor
+generic configuration SensirionSht11C() {
+ provides interface Read<uint16_t> as Temperature;
+ provides interface DeviceMetadata as TemperatureDeviceMetadata;
+ provides interface Read<uint16_t> as Humidity;
+ provides interface DeviceMetadata as HumidityDeviceMetadata;
+}
+implementation {
+ // Instantiate the module providing the HIL interfaces
+ components new SensirionSht11ReaderP();
+
+ Temperature = SensirionSht11ReaderP.Temperature;
+ TemperatureDeviceMetadata = SensirionSht11ReaderP.TemperatureDeviceMetadata;
+ Humidity = SensirionSht11ReaderP.Humidity;
+ HumidityDeviceMetadata = SensirionSht11ReaderP.HumidityDeviceMetadata;
+
+ // And connect it to the HAL component for the Sensirion SHT11
+ components HalSensirionSht11C;
+
+ enum { TEMP_KEY = unique("Sht11.Resource") };
+ enum { HUM_KEY = unique("Sht11.Resource") };
+
+ SensirionSht11ReaderP.TempResource -> HalSensirionSht11C.Resource[ TEMP_KEY ];
+ SensirionSht11ReaderP.Sht11Temp -> HalSensirionSht11C.SensirionSht11[ TEMP_KEY ];
+ SensirionSht11ReaderP.HumResource -> HalSensirionSht11C.Resource[ HUM_KEY ];
+ SensirionSht11ReaderP.Sht11Hum -> HalSensirionSht11C.SensirionSht11[ HUM_KEY ];
+}
+</pre>
+<pre class="literal-block">
+tos/chips/sht11/SensirionSht11ReaderP.nc
+
+// Convert Sensirion SHT11 HAL to HIL interfaces for a single
+// client, performing automatic resource arbitration
+generic module SensirionSht11ReaderP() {
+ provides interface Read<uint16_t> as Temperature;
+ provides interface DeviceMetadata as TemperatureDeviceMetadata;
+ provides interface Read<uint16_t> as Humidity;
+ provides interface DeviceMetadata as HumidityDeviceMetadata;
+
+ // Using separate resource interfaces for temperature and humidity allows
+ // temperature and humidity measurements to be requested simultaneously
+ // (if a single Resource interface was used, a request for temperature would
+ // prevent any humidity requests until the temperature measurement was complete)
+ uses interface Resource as TempResource;
+ uses interface Resource as HumResource;
+ uses interface SensirionSht11 as Sht11Temp;
+ uses interface SensirionSht11 as Sht11Hum;
+}
+implementation {
+ command error_t Temperature.read() {
+ // Start by requesting access to the SHT11
+ return call TempResource.request();
+ }
+
+ event void TempResource.granted() {
+ error_t result;
+ // If the HAL measurement fails, release the SHT11 and signal failure
+ if ((result = call Sht11Temp.measureTemperature()) != SUCCESS) {
+ call TempResource.release();
+ signal Temperature.readDone( result, 0 );
+ }
+ }
+
+ event void Sht11Temp.measureTemperatureDone( error_t result, uint16_t val ) {
+ // Release the SHT11 and signal the result
+ call TempResource.release();
+ signal Temperature.readDone( result, val );
+ }
+
+ command uint8_t TemperatureDeviceMetadata.getSignificantBits() { return 14; }
+
+ command error_t Humidity.read() {
+ // Start by requesting access to the SHT11
+ return call HumResource.request();
+ }
+
+ event void HumResource.granted() {
+ error_t result;
+ // If the HAL measurement fails, release the SHT11 and signal failure
+ if ((result = call Sht11Hum.measureHumidity()) != SUCCESS) {
+ call HumResource.release();
+ signal Humidity.readDone( result, 0 );
+ }
+ }
+
+ event void Sht11Hum.measureHumidityDone( error_t result, uint16_t val ) {
+ // Release the SHT11 and signal the result
+ call HumResource.release();
+ signal Humidity.readDone( result, val );
+ }
+
+ command uint8_t HumidityDeviceMetadata.getSignificantBits() { return 12; }
+
+ // Dummy handlers for unused portions of the HAL interface
+ event void Sht11Temp.resetDone( error_t result ) { }
+ event void Sht11Temp.measureHumidityDone( error_t result, uint16_t val ) { }
+ event void Sht11Temp.readStatusRegDone( error_t result, uint8_t val ) { }
+ event void Sht11Temp.writeStatusRegDone( error_t result ) { }
+
+ event void Sht11Hum.resetDone( error_t result ) { }
+ event void Sht11Hum.measureTemperatureDone( error_t result, uint16_t val ) { }
+ event void Sht11Hum.readStatusRegDone( error_t result, uint8_t val ) { }
+ event void Sht11Hum.writeStatusRegDone( error_t result ) { }
+
+ // We need default handlers as a client may wire to only the Temperature
+ // sensor or only the Humidity sensor
+ default event void Temperature.readDone( error_t result, uint16_t val ) { }
+ default event void Humidity.readDone( error_t result, uint16_t val ) { }
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/chips/sht11/HalSensirionSht11C.nc
+
+// HAL interface to Sensirion SHT11 temperature and humidity sensor
+configuration HalSensirionSht11C {
+ // The SHT11 HAL uses resource arbitration to allow the sensor to shared
+ // between multiple clients and for automatic power management (the SHT11
+ // is switched off when no clients are waiting to use it)
+ provides interface Resource[ uint8_t client ];
+ provides interface SensirionSht11[ uint8_t client ];
+}
+implementation {
+ // The HAL implementation logic
+ components new SensirionSht11LogicP();
+ SensirionSht11 = SensirionSht11LogicP;
+
+ // And it's wiring to the SHT11 HPL - the actual resource management is
+ // provided at the HPL layer
+ components HplSensirionSht11C;
+ Resource = HplSensirionSht11C.Resource;
+ SensirionSht11LogicP.DATA -> HplSensirionSht11C.DATA;
+ SensirionSht11LogicP.CLOCK -> HplSensirionSht11C.SCK;
+ SensirionSht11LogicP.InterruptDATA -> HplSensirionSht11C.InterruptDATA;
+
+ components new TimerMilliC();
+ SensirionSht11LogicP.Timer -> TimerMilliC;
+
+ components LedsC;
+ SensirionSht11LogicP.Leds -> LedsC;
+}
+</pre>
+<pre class="literal-block">
+tos/chips/sht11/SensirionSht11LogicP.nc
+
+generic module SensirionSht11LogicP() {
+ provides interface SensirionSht11[ uint8_t client ];
+
+ uses interface GeneralIO as DATA;
+ uses interface GeneralIO as CLOCK;
+ uses interface GpioInterrupt as InterruptDATA;
+
+ uses interface Timer<TMilli>;
+
+ uses interface Leds;
+}
+implementation {
+
+ ... bus protocol details omitted for brevity ...
+
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/chips/sht11/HplSensirionSht11C.nc
+
+// Low-level, platform-specific glue-code to access the SHT11 sensor found
+// on telos-family motes - here the HPL just provides resource management
+// and access to the SHT11 data, clock and interrupt pins
+configuration HplSensirionSht11C {
+ provides interface Resource[ uint8_t id ];
+ provides interface GeneralIO as DATA;
+ provides interface GeneralIO as SCK;
+ provides interface GpioInterrupt as InterruptDATA;
+}
+implementation {
+ // Pins used to access the SHT11
+ components HplMsp430GeneralIOC;
+
+ components new Msp430GpioC() as DATAM;
+ DATAM -> HplMsp430GeneralIOC.Port15;
+ DATA = DATAM;
+
+ components new Msp430GpioC() as SCKM;
+ SCKM -> HplMsp430GeneralIOC.Port16;
+ SCK = SCKM;
+
+ components new Msp430GpioC() as PWRM;
+ PWRM -> HplMsp430GeneralIOC.Port17;
+
+ // HPL logic for switching the SHT11 on and off
+ components HplSensirionSht11P;
+ HplSensirionSht11P.PWR -> PWRM;
+ HplSensirionSht11P.DATA -> DATAM;
+ HplSensirionSht11P.SCK -> SCKM;
+
+ components new TimerMilliC();
+ HplSensirionSht11P.Timer -> TimerMilliC;
+
+ components HplMsp430InterruptC;
+ components new Msp430InterruptC() as InterruptDATAC;
+ InterruptDATAC.HplInterrupt -> HplMsp430InterruptC.Port15;
+ InterruptDATA = InterruptDATAC.Interrupt;
+
+ // The arbiter and power manager for the SHT11
+ components new FcfsArbiterC( "Sht11.Resource" ) as Arbiter;
+ Resource = Arbiter;
+
+ components new SplitControlPowerManagerC();
+ SplitControlPowerManagerC.SplitControl -> HplSensirionSht11P;
+ SplitControlPowerManagerC.ArbiterInit -> Arbiter.Init;
+ SplitControlPowerManagerC.ArbiterInfo -> Arbiter.ArbiterInfo;
+ SplitControlPowerManagerC.ResourceDefaultOwner -> Arbiter.ResourceDefaultOwner;
+}
+</pre>
+<pre class="literal-block">
+tos/platforms/telosa/chips/sht11/HplSensirionSht11P.nc
+
+// Switch the SHT11 on and off, and handle the 11ms warmup delay
+module HplSensirionSht11P {
+ // The SplitControl interface powers the SHT11 on or off (it's automatically
+ // called by the SHT11 power manager, see HplSensirionSht11C)
+ // We use a SplitControl interface as we need to wait 11ms for the sensor to
+ // warm up
+ provides interface SplitControl;
+ uses interface Timer<TMilli>;
+ uses interface GeneralIO as PWR;
+ uses interface GeneralIO as DATA;
+ uses interface GeneralIO as SCK;
+}
+implementation {
+ task void stopTask();
+
+ command error_t SplitControl.start() {
+ // Power SHT11 on and wait for 11ms
+ call PWR.makeOutput();
+ call PWR.set();
+ call Timer.startOneShot( 11 );
+ return SUCCESS;
+ }
+
+ event void Timer.fired() {
+ signal SplitControl.startDone( SUCCESS );
+ }
+
+ command error_t SplitControl.stop() {
+ // Power the SHT11 off
+ call SCK.makeInput();
+ call SCK.clr();
+ call DATA.makeInput();
+ call DATA.clr();
+ call PWR.clr();
+ post stopTask();
+ return SUCCESS;
+ }
+
+ task void stopTask() {
+ signal SplitControl.stopDone( SUCCESS );
+ }
+}
+</pre>
+</div>
+<div class="section">
+<h2><a id="mda100-sensor-board-directory-organization" name="mda100-sensor-board-directory-organization">4. MDA100 Sensor Board Directory Organization</a></h2>
+<p>Here we show the organization of the sensor board directory for the
+mica-family Xbow MDA100CA and MDA100CB sensor boards, which have
+temperature and light sensors. It is found in
+<tt class="docutils literal"><span class="pre">tos/sensorboards/mda100</span></tt>:</p>
+<pre class="literal-block">
+./tos/sensorboards/mda100:
+.sensor # Compiler configuration
+ArbitratedPhotoDeviceP.nc # Light sensor support component
+ArbitratedTempDeviceP.nc # Temperature sensor support component
+DemoSensorC.nc # Override TinyOS's default sensor
+PhotoC.nc # Light sensor HIL
+PhotoImplP.nc # Light sensor support component
+PhotoTempConfigC.nc # Shared support component
+PhotoTempConfigP.nc # Shared support component
+SharedAnalogDeviceC.nc # Shared support component
+SharedAnalogDeviceP.nc # Shared support component
+TempC.nc # Temperature Sensor HIL
+ca/TempImplP.nc # Temperature sensor support component
+ # (MDA100CA board)
+cb/TempImplP.nc # Temperature sensor support component
+ # (MDA100CB board)
+mda100.h # Header file for mda100
+</pre>
+<p>This sensor board provides only a HIL (PhotoC and TempC components), and overrides the
+TinyOS demo sensor (DemoSensorC). The demo sensor is an alias for PhotoC.</p>
+<p>The two forms of the mda100 differ only by the wiring of the
+temperature sensor. The user has to specify which form of the sensor
+board is in use by providing a <tt class="docutils literal"><span class="pre">-I%T/sensorboards/mda100/ca</span></tt> or
+<tt class="docutils literal"><span class="pre">-I%T/sensorboards/mda100/cb</span></tt> compiler option.</p>
+<p>This sensor board relies on a platform-provided <tt class="docutils literal"><span class="pre">MicaBusC</span></tt> component
+that specifies how the mica-family sensor board bus is connected to
+the microcontroller.</p>
+</div>
+</div>
</div>
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