Low-level ADC peripheral driver interface. More...

Detailed Description

Low-level ADC peripheral driver interface.

This is a very simple ADC interface to allow platform independent access to a MCU's ADC unit(s). This interface is intentionally designed as simple as possible, to allow for very easy implementation and maximal portability.

As of now, the interface does not allow for any advanced ADC concepts (e.g. continuous mode, scan sequences, injections). It is to be determined, if these features will ever be integrated in this interface, or if it does make more sense to create a second, advanced ADC interface for this.

The ADC driver interface is built around the concept of ADC lines. An ADC line in this context is a tuple consisting out of a hardware ADC device (an ADC functional unit on the MCU) and an ADC channel connected to pin.

If a MCU has more than one hardware ADC unit, the ADC lines can be mapped in a way, that it is possible to sample multiple lines in parallel, given that the ADC implementation allows for interruption of the program flow while waiting for the result of a conversion (e.g. through putting the calling thread to sleep while waiting for the conversion results).

(Low-) Power Implications

The ADC peripheral(s) should only be powered on while adc_sample() is active. For implementing adc_sample() this means, that the peripheral should be powered on (i.e. through peripheral clock gating) at the beginning of the function and it should be powered back off at the end of the function.

If the adc_sample() function is implemented in a way, that it will put the active thread to sleep for a certain amount of time, the implementation might need to block certain power states.

Extend interface for continuous mode?


file  adc.h
 Low-level ADC peripheral driver interface definitions.


 Default ADC undefined value.
#define ADC_LINE(x)   (x)
 Default ADC line access macro.


typedef uint_fast8_t adc_t
 Define default ADC type identifier.


enum  adc_res_t {
 Possible ADC resolution settings. More...


int adc_init (adc_t line)
 Initialize the given ADC line. More...
int32_t adc_sample (adc_t line, adc_res_t res)
 Sample a value from the given ADC line. More...

Enumeration Type Documentation

◆ adc_res_t

enum adc_res_t

Possible ADC resolution settings.


ADC resolution: 6 bit.


ADC resolution: 8 bit.


ADC resolution: 10 bit.


ADC resolution: 12 bit.


ADC resolution: 14 bit.


ADC resolution: 16 bit.

Definition at line 93 of file adc.h.

Function Documentation

◆ adc_init()

int adc_init ( adc_t  line)

Initialize the given ADC line.

The ADC line is initialized in synchronous, blocking mode.

[in]lineline to initialize
0 on success
-1 on invalid ADC line

◆ adc_sample()

int32_t adc_sample ( adc_t  line,
adc_res_t  res 

Sample a value from the given ADC line.

This function blocks until the conversion has finished. Please note, that if more than one line share the same ADC device, and if these lines are sampled at the same time (e.g. from different threads), the one called secondly waits for the first to finish before its conversion starts.

[in]lineline to sample
[in]resresolution to use for conversion
the sampled value on success
-1 if resolution is not applicable