-The implementation of the 12-bit ADC stack on the MSP430 is in compliance with
-TEP 101 (tinyos-2.x/doc/txt/tep101.txt) and provides virtualized access to the
-ADC12 by seven different components: AdcReadClientC, AdcReadNowClientC,
+The implementation of the 12-bit ADC stack on the MSP430 is in compliance
+with TEP 101 (tinyos-2.x/doc/txt/tep101.txt) and provides virtualized access
+to the ADC12 by seven different components: AdcReadClientC, AdcReadNowClientC,
AdcReadStreamClientC, Msp430Adc12ClientC, Msp430Adc12ClientAutoDMAC,
Msp430Adc12ClientAutoRVGC and Msp430Adc12ClientAutoDMA_RVGC. A client
component may wire to any of these components and it SHOULD NOT wire to any
explains the difference between the seven components.
+1. HIL
+====================================================================
+
+
A platform-independent application (an application like 'Oscilloscope' that is
supposed to run on, for example, the 'telosb' and 'micaz' platform at the same
time) cannot wire to an MSP430-specific interface like Msp430Adc12SingleChannel
rather about portability it should wire to any of these components.
+2. HAL
+====================================================================
+
An application that is written for an MSP430-based platform like 'eyesIFX' or
'telosb' can access the ADC12 in a more efficient way to, for example, do
high-frequency sampling through the Msp430Adc12SingleChannel interface. On the
* Msp430Adc12ClientAutoDMAC: DMA, but no automatic reference voltage
* Msp430Adc12ClientAutoDMA_RVGC: DMA and automatic reference voltage
+
+PINs
+--------------------------------------------------------------------
+
During a conversion the respective ADC port pin (ports 6.0 - 6.7) must be
configured such that the peripheral module function is selected and the port
pin is switched to input direction. By default, for every client this is done
switched to I/O function mode. To disable this feature please comment out the
"P6PIN_AUTO_CONFIGURE" macro in Msp430Adc12.h.
+
+Configuration for single channel conversions
+--------------------------------------------------------------------
+
+The msp430adc12_channel_config_t struct holds all information needed to
+configure the ADC12 for single channel conversions. The flags come from the
+following MSP430 registers: ADC12CTL0, ADC12CTL1, ADC12MCTLx and TACTL and are
+named according to the "MSP430x1xx Family User's Guide". Their meaning is as
+follows:
+
+ .inch: ADC12 input channel (ADC12MCTLx register). An (external) input
+ channel maps to one of msp430's A0-A7 pins (see device specific data sheet).
+
+ .sref: reference voltage (ADC12MCTLx register). If REFERENCE_VREFplus_AVss
+ or REFERENCE_VREFplus_VREFnegterm is chosen AND the client wires to the
+ Msp430Adc12ClientAutoRVGC or Msp430Adc12ClientAutoDMA_RVGC component then
+ the reference voltage generator has automatically been enabled to the
+ voltage level defined by the "ref2_5v" flag (see below) when the
+ Resource.granted() event is signalled to the client. Otherwise this flag is
+ ignored.
+
+ .ref2_5v: Reference generator voltage level (ADC12CTL0 register). See
+ "sref".
+
+ .adc12ssel: ADC12 clock source select for the sample-hold-time (ADC12CTL1
+ register). In combination the "adc12ssel", "adc12div" and "sht" define the
+ sample-hold-time: "adc12ssel" defines the clock source, "adc12div" defines
+ the ADC12 clock divider and "sht" define the time expressed in jiffies.
+ (the sample-hold-time depends on the resistence of the attached sensor, and
+ is calculated using to the formula in section 17.2.4 of the user guide)
+
+ .adc12div: ADC12 clock divider (ADC12CTL1 register). See "adc12ssel".
+
+ .sht: Sample-and-hold time (ADC12CTL1 register). See "adc12ssel".
+
+ .sampcon_ssel: Clock source for the sampling period (TASSEL for TimerA).
+ When an ADC client specifies a non-zero "jiffies" parameter (using the
+ Msp430Adc12SingleChannel.configureX commands), the ADC
+ implementation will automatically configure TimerA to be sourced from
+ "sampcon_ssel" with an input divider of "sampcon_id". During the sampling
+ process TimerA will be used to trigger a single
+ (Msp430Adc12SingleChannel interface) or a sequence of (Msp430Adc12MultiChannel
+ interface) conversions every "jiffies" clock ticks.
+
+ .sampcon_id: Input divider for "sampcon_ssel" (IDx in TACTL register,
+ TimerA). See "sampcon_ssel".
+
+
+Example: Assuming that SMCLK runs at 1 MHz the following code snippet
+performs 2000 ADC conversions on channel A2 with a sampling period of 4000 Hz.
+The sampling period is defined by the combination of SAMPCON_SOURCE_SMCLK,
+SAMPCON_CLOCK_DIV_1 and a "jiffies" parameter of (1000000 / 4000) = 250.
+
+
+ #define NUM_SAMPLES 2000
+ uint16_t buffer[NUM_SAMPLES];
+
+ const msp430adc12_channel_config_t config = {
+ INPUT_CHANNEL_A2, REFERENCE_VREFplus_AVss, REFVOLT_LEVEL_NONE,
+ SHT_SOURCE_SMCLK, SHT_CLOCK_DIV_1, SAMPLE_HOLD_64_CYCLES,
+ SAMPCON_SOURCE_SMCLK, SAMPCON_CLOCK_DIV_1
+ };
+
+ event void Boot.booted()
+ {
+ call Resource.request();
+ }
+
+ event void Resource.granted()
+ {
+ error_t result;
+ result = call SingleChannel.configureMultiple(&config, buffer, BUFFER_SIZE, 250);
+ if (result == SUCCESS)
+ call SingleChannel.getData();
+ }
+
+ async event uint16_t* SingleChannel.multipleDataReady(uint16_t *buf, uint16_t length)
+ {
+ // buffer contains conversion results
+ }
+
-----
$Date$
projects / tinyos-2.x.git / blobdiff