adc_rp2350.cpp

// ---------------------------------------------
//           This file is part of
//      _  _   __    _   _    __    __
//     ( \/ ) /__\  ( )_( )  /__\  (  )
//      \  / /(__)\  ) _ (  /(__)\  )(__
//      (__)(__)(__)(_) (_)(__)(__)(____)
//
//     Yet Another HW Abstraction Library
//      Copyright (C) Andreas Terstegge
//      BSD Licensed (see file LICENSE)
//
// ---------------------------------------------
//
#include "RP2350.h"
#include "adc_rp2350.h"
#include <cassert>
 
using namespace _IO_BANK0_;
using namespace _RESETS_;
adc_rp2350 adc_rp2350::inst;
 
adc_rp2350::adc_rp2350() {
    // Take ADC out of reset state
    RESETS_CLR.RESET.ADC <<= 1;
    while (!RESETS.RESET_DONE.ADC) ;
    // Enable the ADC
    _ADC_::ADC.CS.EN = 1;
    while (!_ADC_::ADC.CS.READY) ;
    // Prepare ADC inputs
    for (int i=40; i < 48; ++i) {
        // Disable pull-resistors and isolation
        _PADS_BANK0_::PADS_BANK0.GPIO[i].PUE = 0;
        _PADS_BANK0_::PADS_BANK0.GPIO[i].PDE = 0;
        _PADS_BANK0_::PADS_BANK0.GPIO[i].ISO = 0;
    }
}
 
void adc_rp2350::adcMode(uint8_t channel, uint16_t mode) {
    assert(channel < 8);
    assert(mode < ADC::ADC_14_BIT);
    _modes[channel] = mode;
}
 
adc_mode_t adc_rp2350::getMode(uint8_t channel) {
    assert(channel < 8);
    return _modes[channel];
}
 
uint16_t adc_rp2350::adcReadRaw(uint8_t channel) {
    assert(channel < 8);
    // Read the 12 bit ADC result
    _ADC_::ADC.CS.AINSEL = channel;
    _ADC_::ADC.CS.START_ONCE = 1;
    while(!_ADC_::ADC.CS.READY) ;
    uint16_t result = _ADC_::ADC.RESULT;
    // Our ADC has no real 8 or 10 bit modes, so we simulate
    // the behaviour by shifting the result...
    switch(_modes[channel]) {
        case ADC::ADC_8_BIT:
            return result >> 4;
        case ADC::ADC_10_BIT:
            return result >> 2;
        default:
        case ADC::ADC_12_BIT:
            return result;
    }
}
 
float adc_rp2350::adcReadVoltage(uint8_t channel) {
    return rawToVoltage(channel, adcReadRaw(channel));
}
 
float adc_rp2350::rawToVoltage(uint8_t channel, uint16_t raw) {
    float voltage = 3.3f * (float)raw;
    switch(_modes[channel]) {
        case ADC::ADC_8_BIT:
            voltage /= 255.0f;
            break;
        case ADC::ADC_10_BIT:
            voltage /= 1023.0f;
            break;
        default:
        case ADC::ADC_12_BIT:
            voltage /= 4095.0f;
            break;
    }
    return voltage;
}