/** Read the input voltage, represented as a float in the range [0.0, 1.0]
*
* @param obj The analogin object
* @return A floating value representing the current input voltage
*/
float analogin_read(analogin_t *obj)
{
uint16_t reval;
adc_regular_channel_config(obj->adc, 0, obj->channel, ADC_SAMPLETIME_7POINT5);
adc_flag_clear(obj->adc, ADC_FLAG_EOC);
/* start Conversion */
adc_software_trigger_enable(obj->adc, ADC_REGULAR_CHANNEL);
/* wait for conversion to complete */
while (SET != adc_flag_get(obj->adc, ADC_FLAG_EOC)) {
}
/* ADC actual accuracy is 12 bits */
reval = adc_regular_data_read(obj->adc);
return (float)reval * (1.0f / (float)DEV_ADC_ACCURACY_12BIT);
}
/** Read the value from analogin pin, represented as an unsigned 16bit value
*
* @param obj The analogin object
* @return An unsigned 16bit value representing the current input voltage
*/
uint16_t analogin_read_u16(analogin_t *obj)
{
uint16_t reval;
adc_regular_channel_config(obj->adc, 0, obj->channel, ADC_SAMPLETIME_7POINT5);
adc_flag_clear(obj->adc, ADC_FLAG_EOC);
/* start Conversion */
adc_software_trigger_enable(obj->adc, ADC_REGULAR_CHANNEL);
while (SET != adc_flag_get(obj->adc, ADC_FLAG_EOC)) {
}
/* ADC actual accuracy is 12 bits */
reval = adc_regular_data_read(obj->adc);
reval = DEV_ADC_PRECISION_12TO16(reval);
return reval;
}
/** Initialize the analogin peripheral
*
* Configures the pin used by analogin.
* @param obj The analogin object to initialize
* @param pin The analogin pin name
*/
void analogin_init(analogin_t *obj, PinName pin)
{
uint32_t periph;
MBED_ASSERT(obj);
obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
MBED_ASSERT(obj->adc != (ADCName)NC);
uint32_t function = pinmap_function(pin, PinMap_ADC);
MBED_ASSERT(function != (uint32_t)NC);
obj->channel = GD_PIN_CHANNEL_GET(function);
MBED_ASSERT(obj->channel <= ADC_CHANNEL_17);
periph = obj->adc;
/* save the pin for future use */
obj->pin = pin;
/* ADC clock enable and pin number reset */
switch (periph) {
case ADC0:
rcu_periph_clock_enable(RCU_ADC0);
break;
case ADC1:
rcu_periph_clock_enable(RCU_ADC1);
/* reset pin number */
pin = (PinName)(pin & AND_NUMBER);
break;
}
/* ADC clock cannot be greater than 40M */
rcu_adc_clock_config(RCU_CKADC_CKAPB2_DIV4);
if ((ADC_CHANNEL_16 == obj->channel)) {
/* ADC Vrefint enable */
adc_tempsensor_vrefint_enable();
/* set temperature sample flag */
temperature_sample_flag = SET;
}
if ((ADC_CHANNEL_17 == obj->channel)) {
/* ADC Vrefint enable */
adc_tempsensor_vrefint_enable();
}
/* when pin >= ADC_TEMP, it indicates that the channel has no external pins */
if (pin < ADC_TEMP) {
pinmap_pinout(pin, PinMap_ADC);
}
/* ADC configuration */
adc_special_function_config(obj->adc, ADC_SCAN_MODE, DISABLE);
adc_special_function_config(obj->adc, ADC_CONTINUOUS_MODE, DISABLE);
/* ADC trigger config */
adc_external_trigger_source_config(obj->adc, ADC_REGULAR_CHANNEL, ADC0_1_EXTTRIG_REGULAR_NONE);
/* ADC mode config */
adc_mode_config(ADC_MODE_FREE);
/* ADC data alignment config */
adc_data_alignment_config(obj->adc, ADC_DATAALIGN_RIGHT);
/* ADC channel length config */
adc_channel_length_config(obj->adc, ADC_REGULAR_CHANNEL, 1);
if (temperature_sample_flag == SET) {
/* sample temperature needs more time */
adc_regular_channel_config(obj->adc, 0, obj->channel, ADC_SAMPLETIME_239POINT5);
/* clear temperature sample flag */
temperature_sample_flag = RESET;
} else {
adc_regular_channel_config(obj->adc, 0, obj->channel, ADC_SAMPLETIME_28POINT5);
}
adc_external_trigger_config(obj->adc, ADC_REGULAR_CHANNEL, ENABLE);
/* ADC enable */
adc_enable(obj->adc);
/* wait for ADC to stabilize */
_delay(500);
adc_calibration_enable(obj->adc);
}