Class similar to AnalogIn that uses burst mode to run continious background conversions so when the input is read, the last value can immediatly be returned. This slightly modified version allows NC pins.
Dependents: Pinscape_Controller
Fork of FastAnalogIn by
FastAnalogIn.cpp
- Committer:
- Sissors
- Date:
- 2013-05-09
- Revision:
- 0:c2a7b899e6c7
- Child:
- 1:575f4d2d6e9c
File content as of revision 0:c2a7b899e6c7:
#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; }