pio_capture.h File Reference

PIO + DMA frame capture engine. More...

#include <stddef.h>
#include <stdint.h>

Include dependency graph for pio_capture.h:

Go to the source code of this file.

Data Structures
struct	pio_capture_pins_t

Functions
int	pio_capture_init (const pio_capture_pins_t *pins)
	Claim a PIO state machine and DMA channel, load the capture program.
void	pio_capture_deinit (void)
int	pio_capture_frame (uint8_t *buf, size_t len, uint32_t timeout_ms)
	Capture exactly len bytes (one frame) into buf, blocking.
int	pio_capture_frame_variable (uint8_t *buf, size_t capacity, size_t *out_len, uint32_t timeout_ms)
	Capture one variable-length frame (JPEG) into buf.

Detailed Description

PIO + DMA frame capture engine.

The PIO program is assembled at runtime with pio_encode_*(), so all pins come from camera_config_t - there is no .pio file and no pioasm build step (which also keeps the library Arduino-IDE friendly).

Function Documentation

pio_capture_deinit()

void pio_capture_deinit

(

void

)

Release PIO state machine and DMA channel.

pio_capture_frame()

int pio_capture_frame	(	uint8_t *	buf,
		size_t	len,
		uint32_t	timeout_ms )

Capture exactly len bytes (one frame) into buf, blocking.

Waits for the next VSYNC rising edge, then captures while HREF is high, clocked by PCLK, until len bytes are in the buffer.

Parameters

timeout_ms

abort and return PICO timeout error after this long

Returns

0 on success, negative on timeout/error

pio_capture_frame_variable()

int pio_capture_frame_variable	(	uint8_t *	buf,
		size_t	capacity,
		size_t *	out_len,
		uint32_t	timeout_ms )

Capture one variable-length frame (JPEG) into buf.

Uses the continuous capture program: streams from a VSYNC rising edge until VSYNC falls again (frame end), then trims the buffer at the JPEG EOI marker (0xFFD9).

Parameters

buf	destination buffer
capacity	buffer capacity in bytes; a frame larger than this is truncated
out_len	receives the actual frame length in bytes
timeout_ms	abort and return error after this long

Returns

0 on success, negative on timeout/error

pio_capture_init()

int pio_capture_init

(

const pio_capture_pins_t *

pins

)

Claim a PIO state machine and DMA channel, load the capture program.

Returns

0 on success