circuitpython/ports/nrf/hal/hal_adc.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2017 Glenn Ruben Bakke
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdio.h>
#include "mphalport.h"
#include "hal_adc.h"
#ifdef HAL_ADC_MODULE_ENABLED
#define ADC_REF_VOLTAGE_IN_MILLIVOLTS (1200) // Reference voltage (in milli volts) used by ADC while doing conversion.
#define ADC_PRE_SCALING_COMPENSATION (3) // The ADC is configured to use VDD with 1/3 prescaling as input. And hence the result of conversion is to be multiplied by 3 to get the actual value of the battery voltage.
#define DIODE_FWD_VOLT_DROP_MILLIVOLTS (270) // Typical forward voltage drop of the diode (Part no: SD103ATW-7-F) that is connected in series with the voltage supply. This is the voltage drop when the forward current is 1mA. Source: Data sheet of 'SURFACE MOUNT SCHOTTKY BARRIER DIODE ARRAY' available at www.diodes.com.
#define ADC_RESULT_IN_MILLI_VOLTS(ADC_VALUE)\
((((ADC_VALUE) * ADC_REF_VOLTAGE_IN_MILLIVOLTS) / 255) * ADC_PRE_SCALING_COMPENSATION)
static const uint32_t hal_adc_input_lookup[] = {
ADC_CONFIG_PSEL_AnalogInput0 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput1 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput2 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput3 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput4 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput5 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput6 << ADC_CONFIG_PSEL_Pos,
ADC_CONFIG_PSEL_AnalogInput7 << ADC_CONFIG_PSEL_Pos
};
static uint8_t battery_level_in_percent(const uint16_t mvolts)
{
uint8_t battery_level;
if (mvolts >= 3000) {
battery_level = 100;
} else if (mvolts > 2900) {
battery_level = 100 - ((3000 - mvolts) * 58) / 100;
} else if (mvolts > 2740) {
battery_level = 42 - ((2900 - mvolts) * 24) / 160;
} else if (mvolts > 2440) {
battery_level = 18 - ((2740 - mvolts) * 12) / 300;
} else if (mvolts > 2100) {
battery_level = 6 - ((2440 - mvolts) * 6) / 340;
} else {
battery_level = 0;
}
return battery_level;
}
uint16_t hal_adc_channel_value(hal_adc_config_t const * p_adc_conf) {
ADC_BASE->INTENSET = ADC_INTENSET_END_Msk;
ADC_BASE->CONFIG = (ADC_CONFIG_RES_8bit << ADC_CONFIG_RES_Pos)
| (ADC_CONFIG_INPSEL_AnalogInputTwoThirdsPrescaling << ADC_CONFIG_INPSEL_Pos)
| (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos)
| (hal_adc_input_lookup[p_adc_conf->channel])
| (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos);
ADC_BASE->EVENTS_END = 0;
ADC_BASE->ENABLE = ADC_ENABLE_ENABLE_Enabled;
ADC_BASE->EVENTS_END = 0;
ADC_BASE->TASKS_START = 1;
while (!ADC_BASE->EVENTS_END) {
;
}
uint8_t adc_result;
ADC_BASE->EVENTS_END = 0;
adc_result = ADC_BASE->RESULT;
ADC_BASE->TASKS_STOP = 1;
return adc_result;
}
uint16_t hal_adc_battery_level(void) {
ADC_BASE->INTENSET = ADC_INTENSET_END_Msk;
ADC_BASE->CONFIG = (ADC_CONFIG_RES_8bit << ADC_CONFIG_RES_Pos)
| (ADC_CONFIG_INPSEL_SupplyOneThirdPrescaling << ADC_CONFIG_INPSEL_Pos)
| (ADC_CONFIG_REFSEL_VBG << ADC_CONFIG_REFSEL_Pos)
| (ADC_CONFIG_PSEL_Disabled << ADC_CONFIG_PSEL_Pos)
| (ADC_CONFIG_EXTREFSEL_None << ADC_CONFIG_EXTREFSEL_Pos);
ADC_BASE->EVENTS_END = 0;
ADC_BASE->ENABLE = ADC_ENABLE_ENABLE_Enabled;
ADC_BASE->EVENTS_END = 0;
ADC_BASE->TASKS_START = 1;
while (!ADC_BASE->EVENTS_END) {
;
}
uint8_t adc_result;
uint16_t batt_lvl_in_milli_volts;
ADC_BASE->EVENTS_END = 0;
adc_result = ADC_BASE->RESULT;
ADC_BASE->TASKS_STOP = 1;
batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_result) + DIODE_FWD_VOLT_DROP_MILLIVOLTS;
return battery_level_in_percent(batt_lvl_in_milli_volts);
}
#endif // HAL_ADC_MODULE_ENABLED