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adc: adc_read() not check for error (#1575) v2 #1599

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adc: adc_read() not check for error (#1575) v2 #1599

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21 changes: 15 additions & 6 deletions src/rp2_common/hardware_adc/include/hardware/adc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -128,15 +128,24 @@ static inline void adc_set_temp_sensor_enabled(bool enable) {
*
* Performs an ADC conversion, waits for the result, and then returns it.
*
* \return Result of the conversion.
* \return Result of the conversion or negative value on error.
*/
static inline uint16_t adc_read(void) {
static inline int32_t adc_read(void) {
hw_set_bits(&adc_hw->cs, ADC_CS_START_ONCE_BITS);

while ((adc_hw->cs & (ADC_CS_READY_BITS|ADC_CS_ERR_BITS|ADC_CS_ERR_STICKY_BITS))==0) {
tight_loop_contents();
}

while (!(adc_hw->cs & ADC_CS_READY_BITS))
tight_loop_contents();

return (uint16_t) adc_hw->result;
if ((adc_hw->cs & ADC_CS_READY_BITS)>0) {
return adc_hw->result & 0xfff;
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Might be better to use ADC_RESULT_BITS

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I will have a look if that will have benefit. The original code check for the ADC_CS_READY_BITS.

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I believe Peter meant use ADC_RESULT_BITS instead of 0xfff - see https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2040/hardware_regs/include/hardware/regs/adc.h#L111

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Oh, :)
Thanks for the eye opener.

}
if ((adc_hw->cs & ADC_CS_ERR_BITS)>0) {
return -ADC_CS_ERR_BITS;
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It's a bit random to return -ADC_CS_ERR_BITS. It would be better to return a "standard" error code? Maybe PICO_ERROR_GENERIC or PICO_ERROR_NO_DATA?

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I see your point, but if we doing this we can't distinguished what caused the error.

Use
PICO_ERROR_NO_DATA
and additional, define a new code:
PICO_ERROR_ADC_STICKY_BIT

}
/* clear sticky bit */
hw_set_bits(&adc_hw->cs, ADC_CS_ERR_STICKY_BITS);
return -ADC_CS_ERR_STICKY_BITS;
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same comment as above

}

/*! \brief Enable or disable free-running sampling mode
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