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
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; +}