/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Matthias P. Braendli, Maximilien Cuony
 *
 * 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 "analog_input.h"
#include "stm32f4xx_adc.h"
#include <math.h>

void analog_init(void)
{
    // Enable ADC and GPIOA clocks
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    // Set Pin PA5 to analog input
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AN;
    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_5;
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // Init ADC1 for supply measurement
    ADC_CommonInitTypeDef ADC_CommonInitStruct;

    ADC_CommonInitStruct.ADC_Mode = ADC_Mode_Independent;
    ADC_CommonInitStruct.ADC_Prescaler = ADC_Prescaler_Div8;
    ADC_CommonInitStruct.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
    ADC_CommonInitStruct.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
    ADC_CommonInit(&ADC_CommonInitStruct);

    ADC_InitTypeDef ADC_InitStruct;
    ADC_InitStruct.ADC_Resolution = ADC_Resolution_12b;
    ADC_InitStruct.ADC_ScanConvMode = DISABLE;
    ADC_InitStruct.ADC_ContinuousConvMode = ENABLE;
    ADC_InitStruct.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
    ADC_InitStruct.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC1;
    ADC_InitStruct.ADC_DataAlign = ADC_DataAlign_Right;
    ADC_InitStruct.ADC_NbrOfConversion = 1;
    ADC_Init(ADC1, &ADC_InitStruct);

    // Configure ADC1 to use the converted 12V signal (see schematics)
    const uint8_t rank = 1;
    ADC_RegularChannelConfig(ADC1,
            ADC_Channel_5,
            rank,
            ADC_SampleTime_480Cycles);

    // Enable ADC
    ADC_Cmd(ADC1, ENABLE);
}

float analog_measure_12v(void)
{
    ADC_SoftwareStartConv(ADC1); //Start the conversion

    // TODO add timeout
    while (ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);

    const uint16_t raw_value = ADC_GetConversionValue(ADC1);

    const float adc_max_value = (1 << 12);
    const float v_ref = 2.965f;

    // Convert ADC measurement to voltage
    float voltage = ((float)raw_value*v_ref/adc_max_value);

    // Compensate resistor divider on board (see schematic)
    return voltage * 202.0f / 22.0f;
}