From: Kevin Townsend <kevin@ktownsend.com>
Date: Tue, 29 May 2012 19:36:45 +0000 (+0200)
Subject: Added oversampling (courtesy miceuz)
X-Git-Url: https://git.rohieb.name/hackover2013-badge-firmware.git/commitdiff_plain/d5b134a6437719d3471277c1ef1da33b5d45c612

Added oversampling (courtesy miceuz)
---

diff --git a/core/adc/adc.c b/core/adc/adc.c
index 5728545..0a6dd39 100644
--- a/core/adc/adc.c
+++ b/core/adc/adc.c
@@ -162,6 +162,48 @@ uint32_t adcReadSingle (uint8_t channelNum)
   return (adcData);
 }
 
+/**************************************************************************/
+/*! 
+ @brief Returns the oversampled conversion results on the specified ADC channel.
+ 
+ This function will manually start A/D conversions on a single
+ channel sum and divide results to get a value of increased resolution. 
+ 
+ Read more: AVR121: Enhancing ADC resolution by oversampling [http://www.atmel.com/Images/doc8003.pdf]
+ 
+ @param[in]  channelNum
+ The A/D channel [0..7] that will be used during the A/D 
+ conversion.  (Note that only A/D channel's 0..3 are 
+ configured by default in adcInit.)
+
+ @param[in] extraBits
+ Additional bits you want to add to resolution. Hardware resolution is
+ 10bits, if 6 is psecified as extraBits, the resolution will be increated to
+ 16 bit. 
+ 
+ @return     0 if an overrun error occured, otherwise a 10-bit value
+ containing the A/D conversion results.
+ 
+ @warning    Only AD channels 0..3 are configured for A/D in adcInit.
+ If you wish to use A/D pins 4..7 they will also need to
+ be added to the adcInit function.
+ */
+/**************************************************************************/
+
+uint32_t adcReadOversampled (uint8_t channelNum, uint8_t extraBits) {
+    uint32_t sampleCount = 1 << (extraBits * 2);
+    uint16_t i;
+    uint32_t adcOversampled = 0;
+    
+    for(i = 0; i < sampleCount; i++) {
+        uint16_t adcValue = adcReadSingle(channelNum);
+        adcOversampled += adcValue;
+    }
+    
+    adcOversampled = adcOversampled >> extraBits;
+    return adcOversampled;
+}
+
 /**************************************************************************/
 /*! 
     @brief Returns the conversion results on the specified ADC channel.
diff --git a/core/adc/adc.h b/core/adc/adc.h
index 29e168d..a1c3879 100644
--- a/core/adc/adc.h
+++ b/core/adc/adc.h
@@ -42,6 +42,8 @@
 #include "projectconfig.h"
 
 uint32_t   adcRead (uint8_t channelNum);
-void  adcInit (void);
+uint32_t   adcReadOversampled (uint8_t channelNum, uint8_t extraBits);
+uint32_t   adcReadSingle(uint8_t channelNum);
+void       adcInit (void);
 
 #endif