pd_uart.c File Reference

The PD mini's PIO UART. More...

#include "pd_uart.h"
#include "hardware/gpio.h"
#include "hardware/clocks.h"
#include "hardware/pio.h"
#include "pd_uart.pio.h"

Data Structures
struct	[struct].s
	Driver state of the UART: the claimed machines and the pins. More...

Functions
static void	rest (uint8_t pin)
	A pin at rest: an input with a pull-down, driven by nothing here.
bool	pd_uart_open (uint8_t tx, uint8_t rx, uint32_t baud)
	Claim the state machines for tx and rx at baud.
void	pd_uart_close (void)
	Release them; the pins stay at rest.
static void	reset_machines (void)
	Both machines stopped, emptied and back at their first instruction.
void	pd_uart_baud (uint32_t baud)
	Another rate for both machines, between transactions only: nothing happens while the UART is attached.
void	pd_uart_attach (void *ctx)
	Attach the UART to the pins for one transaction.
void	pd_uart_detach (void *ctx)
	Detach the UART; the pins go back to pulled-down inputs.
void	pd_uart_send (void *ctx, const uint8_t *p, size_t n)
	Send bytes on the attached UART.
bool	pd_uart_getc (uint8_t *b)
	A received byte, or false for none.

Variables
static struct	s

Detailed Description

The PD mini's PIO UART.

See pd_uart.h.

SPDX-License-Identifier: MIT

Function Documentation

pd_uart_attach()

void pd_uart_attach

(

void *

ctx

)

Attach the UART to the pins for one transaction.

Parameters

ctx	Unused; passed by the driver's callback table.

pd_uart_baud()

void pd_uart_baud

(

uint32_t

baud

)

Another rate for both machines, between transactions only: nothing happens while the UART is attached.

Parameters

baud	Baud rate.

pd_uart_detach()

void pd_uart_detach

(

void *

ctx

)

Detach the UART; the pins go back to pulled-down inputs.

Parameters

ctx	Unused; passed by the driver's callback table.

pd_uart_getc()

bool pd_uart_getc

(

uint8_t *

b

)

A received byte, or false for none.

Parameters

b	Receives the byte when true is returned.

Returns

true when a byte was taken from the FIFO.

pd_uart_open()

bool pd_uart_open	(	uint8_t	tx,
		uint8_t	rx,
		uint32_t	baud )

Claim the state machines for tx and rx at baud.

False, and nothing held, when no PIO block can reach the pins or has room.

Parameters

tx	GPIO number of the transmit pin.
rx	GPIO number of the receive pin.
baud	Baud rate.

Returns

true when both state machines are claimed.

pd_uart_send()

void pd_uart_send	(	void *	ctx,
		const uint8_t *	p,
		size_t	n )

Send bytes on the attached UART.

Parameters

ctx	Unused; passed by the driver's callback table.
p	Bytes to send.
n	Number of bytes in p.

rest()

void rest ( uint8_t pin )

static

A pin at rest: an input with a pull-down, driven by nothing here.

Parameters

pin	GPIO number.