ERROR running ADC Example: invalid conversion from 'void*'

[rwel59]

starting on some adc stuff and grabbed the example ( esp-idf/examples/peripherals/adc/main/adc1_example_main.c)
compiler errors out on this line: adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));

with the following error:
error: invalid conversion from 'void*' to 'esp_adc_cal_characteristics_t*'

[kolban]

It looks like the line which reads:

Code: Select all

adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));

should likely be:

Code: Select all

adc_chars = (esp_adc_cal_characteristics_t *)calloc(1, sizeof(esp_adc_cal_characteristics_t));

edit your copy of the sample and see if that makes progress.

[rwel59]

thanks Neil, that solved it

[ESP_Angus]

Hi rwel59,

Did you copy the code from a .c file into a .cpp file? C (by default) allows implicit casting from void * to another pointer type, but C++ does not allow this without an explicit cast like the one kolban suggested.

Angus

[rwel59]

Angus,
that is exactly what I did. just started looking at using the ADC's and copied the code from the espidf example.

thanks, I will keep that in mind next time I cut & paste.