adc.h File Reference

G4 ADC public API. DMA-only, DMA-first conversions. More...

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "stm32g474xx.h"
#include "common/phal_G4/dma/dma.h"

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Classes
struct	PHAL_ADC_ChannelConfig_t
	One entry in the conversion sequence. More...
struct	PHAL_ADC_Config_t
	Static configuration for one ADC instance. More...
struct	PHAL_ADC_Handle_t
	Runtime handle for one ADC instance. More...

Functions
bool	PHAL_ADC_init (PHAL_ADC_Handle_t *handle, const PHAL_ADC_Config_t *config)
	Configure an ADC instance and its DMA channel.
bool	PHAL_ADC_readDMA (PHAL_ADC_Handle_t *handle, uint16_t *buffer, uint16_t length)
	Start an asynchronous circular-DMA conversion into buffer
bool	PHAL_ADC_readBlocking (PHAL_ADC_Handle_t *handle, uint16_t *buffer, uint16_t length, uint32_t timeout)
	Synchronous one-buffer conversion using the DMA engine.
bool	PHAL_ADC_stop (PHAL_ADC_Handle_t *handle)
	Abort any transfer in flight and leave the ADC idle.
bool	PHAL_ADC_busy (const PHAL_ADC_Handle_t *handle)
	Check whether a transfer is currently in flight.
void	PHAL_ADC_conversionCompleteCallback (PHAL_ADC_Handle_t *handle)
	Weak callback fired once per completed DMA buffer.

Variables
static constexpr uint8_t	PHAL_ADC_MAX_CHANNEL_COUNT = 16U
	Maximum number of channels one ADC conversion sequence can hold.
static constexpr uint8_t	PHAL_ADC_MAX_CHANNEL_NUMBER = 18U
	Highest ADC channel number (IN18 on the G474)

Detailed Description

G4 ADC public API. DMA-only, DMA-first conversions.

Author

Ronak Jain (jain7.nosp@m.17@p.nosp@m.urdue.nosp@m..edu)

Function Documentation

PHAL_ADC_busy()

bool PHAL_ADC_busy

(

const PHAL_ADC_Handle_t *

handle

)

Check whether a transfer is currently in flight.

Parameters

handle

initialized handle

Returns

true while a PHAL_ADC_readDMA() transfer is running

PHAL_ADC_conversionCompleteCallback()

void PHAL_ADC_conversionCompleteCallback ( PHAL_ADC_Handle_t * handle )

extern

Weak callback fired once per completed DMA buffer.

Called from the DMA interrupt context after each asynchronous circular-DMA buffer completes, and from the caller's context at the end of a successful PHAL_ADC_readBlocking(). On a DMA error, handle->transfer_error is true. Keep it short; the default implementation does nothing.

Parameters

handle

the handle whose transfer just completed

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PHAL_ADC_init()

bool PHAL_ADC_init	(	PHAL_ADC_Handle_t *	handle,
		const PHAL_ADC_Config_t *	config )

Configure an ADC instance and its DMA channel.

What this does, in order:

1. Enables the ADC (and DMA) clocks
2. Runs the ADC hardware calibration
3. Configures the conversion sequence, sample times, and fixed conversion options (12-bit, right-aligned, continuous, DMA-enabled, no oversampling)
4. Enables the ADC and waits until it reports ready
5. Claims the ADC's dedicated DMA channel and enables its interrupt

The DMA channel is fixed per instance (ADC1 -> DMA1 ch1, ADC2 -> DMA2 ch1, ADC3 -> DMA2 ch2, ADC4 -> DMA2 ch3). Only one handle may claim each ADC instance; handles remain claimed for the lifetime of the application.

Parameters

handle	zero-initialized handle to populate
config	static configuration to use; must stay valid for the lifetime of the handle

Returns

true on success, false if the config is invalid, the instance is already claimed, calibration fails, or the DMA channel is taken

Note

Initialization configures the ADC and DMA but does not start sampling; call PHAL_ADC_readDMA() once after initialization to start background acquisition.

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PHAL_ADC_readBlocking()

bool PHAL_ADC_readBlocking	(	PHAL_ADC_Handle_t *	handle,
		uint16_t *	buffer,
		uint16_t	length,
		uint32_t	timeout )

Synchronous one-buffer conversion using the DMA engine.

Starts the circular acquisition, blocks until one buffer has completed, then stops the acquisition. A successful transfer fires PHAL_ADC_conversionCompleteCallback() before returning.

Note: timeout is a count of busy-wait iterations, not a wall-clock time. At 16 MHz one iteration is a handful of CPU cycles; the ADC itself takes roughly (640.5 + 12.5) / fADC seconds per sample (about 163 us at 4 MHz fADC).

Parameters

handle	initialized handle
buffer	destination for the samples
length	number of 16-bit samples to collect
timeout	busy-wait iteration budget (0 = return immediately)

Returns

true if all samples were collected, false on timeout or DMA error

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PHAL_ADC_readDMA()

bool PHAL_ADC_readDMA	(	PHAL_ADC_Handle_t *	handle,
		uint16_t *	buffer,
		uint16_t	length )

Start an asynchronous circular-DMA conversion into buffer

The ADC continuously refreshes buffer and remains active until PHAL_ADC_stop() is called. PHAL_ADC_conversionCompleteCallback() fires (from the DMA interrupt context) after each buffer wrap.

If length is not a multiple of the sequence length, the final burst is a partial sequence (still one sample per conversion).

Fails without starting anything if a transfer is already in flight, the handle was never initialized, buffer is null or not halfword-aligned, or length is zero.

Parameters

handle	initialized handle
buffer	destination, must stay valid until PHAL_ADC_stop() is called
length	number of 16-bit samples to collect (1 - 65535)

Returns

true if the transfer was started, false otherwise

Note

Only one background transfer may be active for a handle.

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PHAL_ADC_stop()

bool PHAL_ADC_stop

(

PHAL_ADC_Handle_t *

handle

)

Abort any transfer in flight and leave the ADC idle.

Safe to call at any time, even with no transfer running (it is then a no-op). Does not fire the completion callback.

Parameters

handle

initialized handle

Returns

true if the handle is initialized, false otherwise

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Variable Documentation

PHAL_ADC_MAX_CHANNEL_COUNT

uint8_t PHAL_ADC_MAX_CHANNEL_COUNT = 16U

staticconstexpr

Maximum number of channels one ADC conversion sequence can hold.

PHAL_ADC_MAX_CHANNEL_NUMBER

uint8_t PHAL_ADC_MAX_CHANNEL_NUMBER = 18U

staticconstexpr

Highest ADC channel number (IN18 on the G474)