#include "gd32_adc.h"
#include "gpio.h"
/* For 12-bits resolution, the total conversion time is 
sampling time + 12.5 ADCCLK cycles */
void adc_init(void){
	rcu_periph_clock_enable(RCU_GPIOA);
	rcu_periph_clock_enable(RCU_GPIOB);	
	gpio_mode_analog_input(GPIOA, GPIO_PIN_1|GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7);
	gpio_mode_analog_input(GPIOB, GPIO_PIN_1|GPIO_PIN_0);

    /* config ADC clock */
    rcu_adc_clock_config(RCU_ADCCK_AHB_DIV3); //adc clock:28M 

	rcu_periph_clock_enable(RCU_ADC);
	adc_deinit();

	adc_resolution_config(ADC_RESOLUTION_12B);
    /* ADC trigger config */
    adc_external_trigger_source_config(ADC_REGULAR_CHANNEL, ADC_EXTTRIG_REGULAR_NONE); 
	adc_special_function_config(ADC_SCAN_MODE,ENABLE);
	/* ADC data alignment config */
	adc_data_alignment_config(ADC_DATAALIGN_RIGHT);
	/* ADC channel length config */
	adc_channel_length_config(ADC_REGULAR_CHANNEL, 1);

	adc_discontinuous_mode_config(ADC_REGULAR_CHANNEL, 1);

	//hardware oversample to 16bit
	adc_oversample_mode_config(ADC_OVERSAMPLING_ONE_CONVERT, ADC_OVERSAMPLING_SHIFT_4B, ADC_OVERSAMPLING_RATIO_MUL256);
}

int adc_sample(int chan, int calibration){
	int value = -0xFFFFFF;
	if (chan == ADC_CHAN_AUX_CURR || chan == ADC_CHAN_IMON || chan == ADC_CHAN_VMON){
		adc_oversample_mode_enable();
	}else {
		adc_oversample_mode_disable();
	}
    /* ADC regular channel config */
    adc_regular_channel_config(0, chan, ADC_SAMPLETIME_7POINT5);//7.5 + 12.5 = 20 cycle, 20/(28*1000000)
	adc_enable();
	if (calibration) {
		/* ADC calibration and reset calibration */
    	adc_calibration_enable();
	}
	
	adc_software_trigger_enable(ADC_REGULAR_CHANNEL);
    while(SET != adc_flag_get(ADC_FLAG_EOC));
    value = adc_regular_data_read();
	adc_flag_clear(ADC_FLAG_EOC);
	adc_disable();

	return value;
}