From 5d14306e3c5586233f74d0a6080c906b9305ea81 Mon Sep 17 00:00:00 2001
From: smckown <smckown@4bc1554a-c7f2-4f65-a403-e0be01f0239c>
Date: Tue, 16 Sep 2008 14:17:50 +0000
Subject: [PATCH] Incorporate a BusyWait interface for allowing platforms to
 override the timing control necessary when bit-banging the SHT1X clock.

---
 tos/chips/sht11/SensirionBusyWaitC.nc   | 48 +++++++++++++++++++++++++
 tos/chips/sht11/SensirionSht11LogicP.nc | 10 ++++++
 2 files changed, 58 insertions(+)
 create mode 100644 tos/chips/sht11/SensirionBusyWaitC.nc

diff --git a/tos/chips/sht11/SensirionBusyWaitC.nc b/tos/chips/sht11/SensirionBusyWaitC.nc
new file mode 100644
index 00000000..61e441ad
--- /dev/null
+++ b/tos/chips/sht11/SensirionBusyWaitC.nc
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2008, Titanium Mirror, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - Neither the name of Titanium Mirror, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+ 
+/**
+ * This BusyWait interface is solely designed for use in providing the
+ * necessary 5us timing when bit-banging the SHT1X sensibus clock pin in
+ * SensirionSht11LogicP, which only calls BusyWait.wait() with an argument of
+ * 5 (us).  For most microprocessors running at under 10MHz, the implementation
+ * need do nothing to achieve the required timing.  This default implementation
+ * is designed for such platforms.  Platforms using higher performance
+ * microprocessors may need to override this component with a platform-specific
+ * one to provide the necessary wait time.
+ * 
+ * @author R. Steve McKown <smckown@gmail.com>
+ */
+ 
+module SensirionBusyWaitC {
+  provides interface BusyWait<TMicro, uint8_t>;
+}
+implementation {
+  async command void BusyWait.wait(uint8_t us) {}
+}
diff --git a/tos/chips/sht11/SensirionSht11LogicP.nc b/tos/chips/sht11/SensirionSht11LogicP.nc
index ce4aa6ca..f3f02697 100644
--- a/tos/chips/sht11/SensirionSht11LogicP.nc
+++ b/tos/chips/sht11/SensirionSht11LogicP.nc
@@ -57,6 +57,7 @@ generic module SensirionSht11LogicP() {
   uses interface GeneralIO as CLOCK;
   uses interface GpioInterrupt as InterruptDATA;
 
+  uses interface BusyWait<TMicro, uint8_t>;
   uses interface Timer<TMilli>;
 
   uses interface Leds;
@@ -240,11 +241,17 @@ implementation {
     call DATA.makeOutput();
     call DATA.set();
     call CLOCK.clr();
+    call BusyWait.wait(5);
     call CLOCK.set();
+    call BusyWait.wait(5);
     call DATA.clr();
+    call BusyWait.wait(5);
     call CLOCK.clr();
+    call BusyWait.wait(5);
     call CLOCK.set();
+    call BusyWait.wait(5);
     call DATA.set();
+    call BusyWait.wait(5);
     call CLOCK.clr();
   }
 
@@ -261,6 +268,7 @@ implementation {
 	call DATA.clr();
       byte = byte << 1;
       call CLOCK.set();
+      call BusyWait.wait(5);
       call CLOCK.clr();
     }
   }
@@ -373,6 +381,7 @@ implementation {
     call DATA.makeOutput();
     call DATA.clr();
     call CLOCK.set();
+    call BusyWait.wait(5);
     call CLOCK.clr();
     call DATA.makeInput();
     call DATA.set();
@@ -382,6 +391,7 @@ implementation {
     call DATA.makeOutput();
     call DATA.set();
     call CLOCK.set();
+    call BusyWait.wait(5);
     call CLOCK.clr();
   }
 
-- 
2.39.2