Diff: FastAnalogIn.cpp

Revision:

0:c2a7b899e6c7

Child:

1:575f4d2d6e9c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FastAnalogIn.cpp	Thu May 09 17:46:32 2013 +0000
@@ -0,0 +1,136 @@
+#include "FastAnalogIn.h"
+static inline int div_round_up(int x, int y)
+{
+    return (x + (y - 1)) / y;
+}
+
+const PinMap FastAnalogIn::PinMap_ADC[] = {
+    {P0_23, ADC0_0, 1},
+    {P0_24, ADC0_1, 1},
+    {P0_25, ADC0_2, 1},
+    {P0_26, ADC0_3, 1},
+    {P1_30, ADC0_4, 3},
+    {P1_31, ADC0_5, 3},
+    {P0_2,  ADC0_7, 2},
+    {P0_3,  ADC0_6, 2},
+    {NC,    NC,     0}
+};
+
+int FastAnalogIn::channel_usage[] = {0};
+
+
+FastAnalogIn::FastAnalogIn(PinName pin, bool enabled)
+{
+    ADCnumber = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
+    if (ADCnumber == (uint32_t)NC)
+        error("ADC pin mapping failed");
+    datareg = (uint32_t*) (&LPC_ADC->ADDR0 + ADCnumber);
+
+    // ensure power is turned on
+    LPC_SC->PCONP |= (1 << 12);
+    // set PCLK of ADC to /1
+    LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
+    LPC_SC->PCLKSEL0 |= (0x1 << 24);
+    uint32_t PCLK = SystemCoreClock;
+
+    // calculate minimum clock divider
+    //  clkdiv = divider - 1
+    uint32_t MAX_ADC_CLK = 13000000;
+    uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
+    // Set the clkdiv
+    LPC_ADC->ADCR &= ~(255<<8);
+    LPC_ADC->ADCR |= clkdiv<<8;
+
+    //Enable ADC:
+    LPC_ADC->ADCR |= 1<<21;
+
+    //Enable burstmode, set start as zero
+    LPC_ADC->ADCR |= 1<<16;
+    LPC_ADC->ADCR &= ~(7<<24);
+
+    //Map pins
+    pinmap_pinout(pin, PinMap_ADC);
+
+    //Enable channel
+    running = false;
+    enable(enabled);
+
+};
+
+FastAnalogIn::~FastAnalogIn(void)
+{
+    disable();
+}
+
+
+void FastAnalogIn::enable(bool enabled)
+{
+    //If currently not running
+    if (!running) {
+        if (enabled) {
+            //Enable the ADC channel
+            channel_usage[ADCnumber]++;
+            LPC_ADC->ADCR |= (1<<ADCnumber);
+            running = true;
+        } else
+            disable();
+    }
+};
+
+void FastAnalogIn::disable( void )
+{
+    //If currently running
+    if (running) {
+        channel_usage[ADCnumber]--;
+        
+        if (channel_usage[ADCnumber]==0)
+            LPC_ADC->ADCR &= ~(1<<ADCnumber);
+    }
+    running = false;
+};
+
+unsigned short FastAnalogIn::read_u16( void )
+{
+    //If object is enabled return current value of datareg
+    if (running ) {
+        unsigned int retval = *datareg;
+        retval = retval >> 4;
+        retval = retval & 4095;
+        return retval;
+    }
+    //If it isn't running, enable it and wait until new value is written to datareg
+    else {
+        //Force a read to clear done bit, enable the ADC channel
+        volatile unsigned int retval = *datareg;
+        enable();
+        //Wait until it is converted
+        while(1) {
+            wait_us(1);
+            retval = *datareg;
+            if ((retval>>31) == 1)
+                break;
+        }
+        
+        //Do a second conversion since first one always fails for some reason
+        while(1) {
+            wait_us(1);
+            retval = *datareg;
+            if ((retval>>31) == 1)
+                break;
+        }
+
+        //Disable again
+        disable();
+        retval = retval >> 4;
+        retval = retval & 4095;
+        return retval;
+    }
+
+
+};
+
+float FastAnalogIn::read( void )
+{
+    unsigned short value = read_u16();
+    return (float)value/4095;
+}