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 Erik -

FastAnalogIn_LPC11UXX.cpp

Committer:
mjr
Date:
2015-12-19
Revision:
11:234c5cd2b8de
Parent:
10:afc3b84dbbd6

File content as of revision 11:234c5cd2b8de:

#ifdef TARGET_LPC11UXX

#include "FastAnalogIn.h"
static inline int div_round_up(int x, int y)
{
    return (x + (y - 1)) / y;
}

#define LPC_IOCON0_BASE (LPC_IOCON_BASE)
#define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
#define MAX_ADC_CLK     4500000

static const PinMap PinMap_ADC[] = {
    {P0_11, ADC0_0, 0x02},
    {P0_12, ADC0_1, 0x02},
    {P0_13, ADC0_2, 0x02},
    {P0_14, ADC0_3, 0x02},
    {P0_15, ADC0_4, 0x02},
    {P0_16, ADC0_5, 0x01},
    {P0_22, ADC0_6, 0x01},
    {P0_23, ADC0_7, 0x01},
    {NC   , NC    , 0   }
};

static int channel_usage[8] = {0,0,0,0,0,0,0,0};



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->DR0 + ADCnumber);
    
    // Power up ADC
    LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
    LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
 
    uint32_t pin_number = (uint32_t)pin;
    __IO uint32_t *reg = (pin_number < 32) ? (__IO uint32_t*)(LPC_IOCON0_BASE + 4 * pin_number) : (__IO uint32_t*)(LPC_IOCON1_BASE + 4 * (pin_number - 32));
 
    // set pin to ADC mode
    *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
 
    uint32_t clkdiv = div_round_up(SystemCoreClock, MAX_ADC_CLK) - 1;
 
    LPC_ADC->CR = (LPC_ADC->CR & 0xFF)      // keep current channels
                | (clkdiv << 8) // max of 4.5MHz
                | (1 << 16)     // BURST = 1, hardware controlled
                | ( 0 << 17 );  // CLKS = 0, we stick to 10 bit mode
    
    pinmap_pinout(pin, PinMap_ADC);

    //Enable channel
    running = false;
    enable(enabled);

}

void FastAnalogIn::enable(bool enabled)
{
    //If currently not running
    if (!running) {
        if (enabled) {
            //Enable the ADC channel
            channel_usage[ADCnumber]++;
            LPC_ADC->CR |= (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->CR &= ~(1<<ADCnumber);
    }
    running = false;
}

unsigned short FastAnalogIn::read_u16( void )
{
    unsigned int retval;
    //If object is enabled return current value of datareg
    if (running)
        retval = *datareg;
 
    //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
        retval = *datareg;
        enable();
        //Wait until it is converted
        while(1) {
            retval = *datareg;
            if ((retval>>31) == 1)
                break;
        }
        //Disable again
        disable();
    }
    
    //Do same thing as standard mbed lib, unused bit 0-3, replicate 4-7 in it
    retval &= ~0xFFFF003F;
    retval |= (retval >> 6) & 0x003F;
    return retval;
}
#endif //defined TARGET_LPC11UXX