furi_hal_adc.h File Reference

ADC HAL API. More...

#include <furi.h>
#include <stdbool.h>
#include <stdint.h>

Go to the source code of this file.

Typedefs
typedef struct FuriHalAdcHandle	FuriHalAdcHandle

Enumerations
enum	FuriHalAdcScale { FuriHalAdcScale2048 , FuriHalAdcScale2500 }
enum	FuriHalAdcClock { FuriHalAdcClockSync16 , FuriHalAdcClockSync32 , FuriHalAdcClockSync64 }
enum	FuriHalAdcOversample {   FuriHalAdcOversample2 , FuriHalAdcOversample4 , FuriHalAdcOversample8 , FuriHalAdcOversample16 ,   FuriHalAdcOversample32 , FuriHalAdcOversample64 , FuriHalAdcOversample128 , FuriHalAdcOversample256 ,   FuriHalAdcOversampleNone }
enum	FuriHalAdcSamplingTime {   FuriHalAdcSamplingtime2_5 , FuriHalAdcSamplingtime6_5 , FuriHalAdcSamplingtime12_5 , FuriHalAdcSamplingtime24_5 ,   FuriHalAdcSamplingtime47_5 , FuriHalAdcSamplingtime92_5 , FuriHalAdcSamplingtime247_5 , FuriHalAdcSamplingtime640_5 }
enum	FuriHalAdcChannel {   FuriHalAdcChannel0 , FuriHalAdcChannel1 , FuriHalAdcChannel2 , FuriHalAdcChannel3 ,   FuriHalAdcChannel4 , FuriHalAdcChannel5 , FuriHalAdcChannel6 , FuriHalAdcChannel7 ,   FuriHalAdcChannel8 , FuriHalAdcChannel9 , FuriHalAdcChannel10 , FuriHalAdcChannel11 ,   FuriHalAdcChannel12 , FuriHalAdcChannel13 , FuriHalAdcChannel14 , FuriHalAdcChannel15 ,   FuriHalAdcChannel16 , FuriHalAdcChannel17 , FuriHalAdcChannel18 , FuriHalAdcChannelVREFINT ,   FuriHalAdcChannelTEMPSENSOR , FuriHalAdcChannelVBAT , FuriHalAdcChannelNone }

Functions
void	furi_hal_adc_init (void)
	Initialize ADC subsystem.
FuriHalAdcHandle *	furi_hal_adc_acquire (void)
	Acquire ADC handle.
void	furi_hal_adc_release (FuriHalAdcHandle *handle)
	Release ADC handle.
void	furi_hal_adc_configure (FuriHalAdcHandle *handle)
	Configure with default parameters and enable ADC.
void	furi_hal_adc_configure_ex (FuriHalAdcHandle *handle, FuriHalAdcScale scale, FuriHalAdcClock clock, FuriHalAdcOversample oversample, FuriHalAdcSamplingTime sampling_time)
	Configure with extended parameters and enable ADC.
uint16_t	furi_hal_adc_read (FuriHalAdcHandle *handle, FuriHalAdcChannel channel)
	Read single ADC value.
float	furi_hal_adc_convert_to_voltage (FuriHalAdcHandle *handle, uint16_t value)
	Convert sampled value to voltage.
float	furi_hal_adc_convert_vref (FuriHalAdcHandle *handle, uint16_t value)
	Convert sampled VREFINT value to voltage.
float	furi_hal_adc_convert_temp (FuriHalAdcHandle *handle, uint16_t value)
	Convert sampled TEMPSENSOR value to temperature.
float	furi_hal_adc_convert_vbat (FuriHalAdcHandle *handle, uint16_t value)
	Convert sampled VBAT value to voltage.

Detailed Description

ADC HAL API.

For the sake of simplicity this API implements only small subset of what ADC is actually capable of. Feel free to visit Reference Manual for STM32WB series and implement any other modes by your self.

Couple things to keep in mind:

• ADC resolution is 12 bits, but effective number of bits is ~10 at the best and further depends on how you use and configure it.
• Analog domain is fed from SMPS which is quite noisy.
• Because of that we use internal on-chip voltage reference for ADC.
• It's capable of producing 2 voltages: 2.5V and 2.048V. This is the scale for your signal.
• Only single ended mode is available. But you can implement differential one by using low level controls directly.
• No DMA or interrupt API available at this point. But can be implemented with low level controls.

How to use:

• furi_hal_gpio_init - Configure your pins in GpioModeAnalog
• furi_hal_adc_acquire - acquire ADC handle to work with
• furi_hal_adc_configure - configure ADC block
• furi_hal_adc_read - read value
• furi_hal_adc_release - release ADC handle

Enumeration Type Documentation

FuriHalAdcChannel

enum FuriHalAdcChannel

Enumerator
FuriHalAdcChannel0	Internal channel, see FuriHalAdcChannelVREFINT.
FuriHalAdcChannel1	Channel 1p.
FuriHalAdcChannel2	Channel 2p or 1n.
FuriHalAdcChannel3	Channel 3p or 2n.
FuriHalAdcChannel4	Channel 4p or 3n.
FuriHalAdcChannel5	Channel 5p or 4n.
FuriHalAdcChannel6	Channel 6p or 5n.
FuriHalAdcChannel7	Channel 7p or 6n.
FuriHalAdcChannel8	Channel 8p or 7n.
FuriHalAdcChannel9	Channel 9p or 8n.
FuriHalAdcChannel10	Channel 10p or 9n.
FuriHalAdcChannel11	Channel 11p or 10n.
FuriHalAdcChannel12	Channel 12p or 11n.
FuriHalAdcChannel13	Channel 13p or 12n.
FuriHalAdcChannel14	Channel 14p or 13n.
FuriHalAdcChannel15	Channel 15p or 14n.
FuriHalAdcChannel16	Channel 16p or 15n.
FuriHalAdcChannel17	Internal channel, see FuriHalAdcChannelTEMPSENSOR.
FuriHalAdcChannel18	Internal channel, see FuriHalAdcChannelVBAT.
FuriHalAdcChannelVREFINT	Special channel for VREFINT, used for calibration and self test.
FuriHalAdcChannelTEMPSENSOR	Special channel for on-die temperature sensor, requires at least 5us of sampling time.
FuriHalAdcChannelVBAT	Special channel for VBAT/3 voltage, requires at least 12us of sampling time.
FuriHalAdcChannelNone	No channel.

FuriHalAdcClock

enum FuriHalAdcClock

Enumerator
FuriHalAdcClockSync16	16MHZ, synchronous
FuriHalAdcClockSync32	32MHZ, synchronous
FuriHalAdcClockSync64	64MHz, synchronous

FuriHalAdcOversample

enum FuriHalAdcOversample

Enumerator
FuriHalAdcOversample2	ADC will take 2 samples per each value.
FuriHalAdcOversample4	ADC will take 4 samples per each value.
FuriHalAdcOversample8	ADC will take 8 samples per each value.
FuriHalAdcOversample16	ADC will take 16 samples per each value.
FuriHalAdcOversample32	ADC will take 32 samples per each value.
FuriHalAdcOversample64	ADC will take 64 samples per each value.
FuriHalAdcOversample128	ADC will take 128 samples per each value.
FuriHalAdcOversample256	ADC will take 256 samples per each value.
FuriHalAdcOversampleNone	disable oversampling

FuriHalAdcSamplingTime

enum FuriHalAdcSamplingTime

Enumerator
FuriHalAdcSamplingtime2_5	Sampling time 2.5 ADC clock.
FuriHalAdcSamplingtime6_5	Sampling time 6.5 ADC clock.
FuriHalAdcSamplingtime12_5	Sampling time 12.5 ADC clock.
FuriHalAdcSamplingtime24_5	Sampling time 24.5 ADC clock.
FuriHalAdcSamplingtime47_5	Sampling time 47.5 ADC clock.
FuriHalAdcSamplingtime92_5	Sampling time 92.5 ADC clock.
FuriHalAdcSamplingtime247_5	Sampling time 247.5 ADC clock.
FuriHalAdcSamplingtime640_5	Sampling time 640.5 ADC clock.

FuriHalAdcScale

enum FuriHalAdcScale

Enumerator
FuriHalAdcScale2048	2.048V scale
FuriHalAdcScale2500	2.5V scale

Function Documentation

furi_hal_adc_acquire()

FuriHalAdcHandle * furi_hal_adc_acquire

(

void

)

Acquire ADC handle.

Enables appropriate power and clocking domains

Returns

FuriHalAdcHandle pointer

furi_hal_adc_configure()

void furi_hal_adc_configure

(

FuriHalAdcHandle *

handle

)

Configure with default parameters and enable ADC.

Parameters used:

• FuriHalAdcScale2048 - 2.048V VREF Scale. Your signal should be in 0 - 2.048V range.
• FuriHalAdcClockSync64 - Clocked from sysclk bus at 64MHz in synchronous mode. Fast, no delay on data bus access.
• FuriHalAdcOversample64 - Going to acquire and average 64 samples. For circuits with slowly or not changing signal. Total time per one read: (1/64)*(12.5+247.5)*64 = 260us. The best results you'll get if your signal will stay on the same level all this time.
• FuriHalAdcSamplingtime247_5 - Sampling(transfer from source to internal sampling capacitor) time is 247.5 ADC clocks: (1/64)*247.5 = 3.8671875us. For relatively high impedance circuits.

Also keep your measurement circuit impedance under 10KOhm or oversampling results will be compromised. Verify your signal with oscilloscope(you may need fast oscilloscope: 200MHz bandwidth, 125MS/s), ensure that signal is not distorted by sampling.

Those parameters were optimized for 0 - 2.048 voltage measurement with ~0.1% precision. You can get more, but it will require some magic.

Parameters

handle

The ADC handle

furi_hal_adc_configure_ex()

void furi_hal_adc_configure_ex	(	FuriHalAdcHandle *	handle,
		FuriHalAdcScale	scale,
		FuriHalAdcClock	clock,
		FuriHalAdcOversample	oversample,
		FuriHalAdcSamplingTime	sampling_time )

Configure with extended parameters and enable ADC.

General advice is to start with default parameters, figure out what exactly is not working for you and then tune it. Also in some cases changing circuit(adding caps, lowering impedance, adding opamp) may be better than changing parameters.

Warning

In general ADC is a world of magic: make sure that you understand how your circuit and ADC works. Then carefully read STM32WB series reference manual. Setting incorrect parameters leads to very poor results. Also internal channels require special settings.

Parameters

	handle	The ADC handle
[in]	scale	The ADC voltage scale
[in]	clock	The ADC clock
[in]	oversample	The ADC oversample mode
[in]	sampling_time	The ADC sampling time

furi_hal_adc_convert_temp()

float furi_hal_adc_convert_temp	(	FuriHalAdcHandle *	handle,
		uint16_t	value )

Convert sampled TEMPSENSOR value to temperature.

Parameters

	handle	The ADC handle
[in]	value	The value acquired with furi_hal_adc_read for FuriHalAdcChannelTEMPSENSOR channel

Returns

temperature in degree C

furi_hal_adc_convert_to_voltage()

float furi_hal_adc_convert_to_voltage	(	FuriHalAdcHandle *	handle,
		uint16_t	value )

Convert sampled value to voltage.

Parameters

	handle	The ADC handle
[in]	value	The value acquired with furi_hal_adc_read

Returns

Voltage in mV

furi_hal_adc_convert_vbat()

float furi_hal_adc_convert_vbat	(	FuriHalAdcHandle *	handle,
		uint16_t	value )

Convert sampled VBAT value to voltage.

Parameters

	handle	The ADC handle
[in]	value	The value acquired with furi_hal_adc_read for FuriHalAdcChannelVBAT channel

Returns

Voltage in mV

furi_hal_adc_convert_vref()

float furi_hal_adc_convert_vref	(	FuriHalAdcHandle *	handle,
		uint16_t	value )

Convert sampled VREFINT value to voltage.

Parameters

	handle	The ADC handle
[in]	value	The value acquired with furi_hal_adc_read for FuriHalAdcChannelVREFINT channel

Returns

Voltage in mV

furi_hal_adc_read()

uint16_t furi_hal_adc_read	(	FuriHalAdcHandle *	handle,
		FuriHalAdcChannel	channel )

Read single ADC value.

Parameters

	handle	The ADC handle
[in]	channel	The channel to sample

Returns

value, 12 bits

furi_hal_adc_release()

void furi_hal_adc_release

(

FuriHalAdcHandle *

handle

)

Release ADC handle.

Parameters

handle

The ADC handle