pifacedigital.h File Reference

A simple static library for controlling PiFace Digital. See mcp23s17.h for more register definitions. More...

#include <stdint.h>

Go to the source code of this file.

Macros
#define	OUTPUT   0x12
#define	INPUT   0x13

Functions
int	pifacedigital_open (uint8_t hw_addr)
int	pifacedigital_open_noinit (uint8_t hw_addr)
void	pifacedigital_close (uint8_t hw_addr)
uint8_t	pifacedigital_read_reg (uint8_t reg, uint8_t hw_addr)
void	pifacedigital_write_reg (uint8_t data, uint8_t reg, uint8_t hw_addr)
uint8_t	pifacedigital_read_bit (uint8_t bit_num, uint8_t reg, uint8_t hw_addr)
void	pifacedigital_write_bit (uint8_t data, uint8_t bit_num, uint8_t reg, uint8_t hw_addr)
uint8_t	pifacedigital_digital_read (uint8_t pin_num)
void	pifacedigital_digital_write (uint8_t pin_num, uint8_t value)
int	pifacedigital_enable_interrupts (void)
int	pifacedigital_disable_interrupts (void)
int	pifacedigital_wait_for_input (uint8_t *data, int timeout, uint8_t hw_addr)

Detailed Description

A simple static library for controlling PiFace Digital. See mcp23s17.h for more register definitions.

Copyright (C) 2013 Thomas Preston thoma.nosp@m.s.pr.nosp@m.eston.nosp@m.@ope.nosp@m.nlx.o.nosp@m.rg.u.nosp@m.k

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Function Documentation

void pifacedigital_close

(

uint8_t

hw_addr

)

Closes a PiFace Digital with the specified hardware address (turns off interrupts, closes file descriptor if it is no longer needed).

Example:

pifacedigital_close(0);

Parameters

hw_addr

The hardware address (configure with jumpers: JP1 and JP2).

uint8_t pifacedigital_digital_read

(

uint8_t

pin_num

)

Read from the input port on PiFace Digital 0. If you want to read from other ports or PiFace Digital's with other hardware addresses then use the more powerful function <pifacedigital_read_bit>"()".

Example (read from bit 6 of INPUT on PiFace Digital 0):

pifacedigital_digital_read(6);

Parameters

pin_num

The pin number to read from.

void pifacedigital_digital_write	(	uint8_t	pin_num,
		uint8_t	value
	)

Write to the output port on PiFace Digital 0. If you want to write to other ports or PiFace Digital's with other hardware addresses then use the more powerful function <pifacedigital_write_bit>"()".

Example (write 1 to bit 3 of OUTPUT on PiFace Digital 0):

pifacedigital_digital_write(3, 1);

Parameters

pin_num	The pin number to write to.
value	The value to write.

int pifacedigital_disable_interrupts

(

void

)

Disables interrupts and exports to the GPIO connection from the PiFaceDigital.

Example:

pifacedigital_disable_interrupts();

Returns

int 0 on success

int pifacedigital_enable_interrupts

(

void

)

Enables interrupts and exports to the GPIO connection from the PiFaceDigital.

Example:

pifacedigital_enable_interrupts();

Returns

int 0 on success

int pifacedigital_open

(

uint8_t

hw_addr

)

Opens and initialises a PiFace Digital with the specified hardware address. Returns a file descriptor for making raw SPI transactions to the MCP23S17 (for advanced users only).

Example:

pifacedigital_open(0);
int pifacedigital_fd = pifacedigital_open(0); // advanced

Parameters

hw_addr

The hardware address (configure with jumpers: JP1 and JP2).

int pifacedigital_open_noinit

(

uint8_t

hw_addr

)

Opens a PiFace Digital with the specified hardware address without initialising it. Returns a file descriptor for making raw SPI transactions to the MCP23S17 (for advanced users only).

Example:

pifacedigital_open_noinit(0);
int pifacedigital_fd = pifacedigital_open_noinit(0); // advanced

Parameters

hw_addr

The hardware address (configure with jumpers: JP1 and JP2).

uint8_t pifacedigital_read_bit	(	uint8_t	bit_num,
		uint8_t	reg,
		uint8_t	hw_addr
	)

Read a bit from a register on PiFace Digital.

Example (read bit 3 of INPUT on PiFace Digital 0):

uint8_t bit_value = pifacedigital_read_bit(3, INPUT, 0);

Parameters

bit_num	The bit number to read from.
reg	The register to write to (example: INPUT, OUTPUT, GPPUB).
hw_addr	The hardware address (configure with jumpers: JP1 and JP2).

uint8_t pifacedigital_read_reg	(	uint8_t	reg,
		uint8_t	hw_addr
	)

Reads a register from PiFace Digital.

Example (read INPUT from PiFace Digital 0):

uint8_t value = pifacedigital_read_reg(INPUT, 0);

Parameters

reg	The register to read from (example: INPUT, OUTPUT).
hw_addr	The hardware address (configure with jumpers: JP1 and JP2).

int pifacedigital_wait_for_input	(	uint8_t *	data,
		int	timeout,
		uint8_t	hw_addr
	)

Waits for a change of any of the input pins on the PiFace Digital, and returns the current state of all inputs as each bit of the 8-bit return value. Requires that interrupts are enabled with pifacedigital_enable_interrupts() first.

Note

Changed signature in v0.3.0 (from v0.2.0). See CHANGELOG.

Example:

pifacedigital_open(0);
pifacedigital_enable_interrupts();
uint8_t inputs;
int success = pifacedigital_wait_for_input(&inputs, 5, 0);
if (success > 0) {
    printf("Interrupt detected. Inputs: 0x%x\n", inputs);
} else if (success == 0) {
    printf("Timeout\n");
} else {
    printf("Error\n");
}
pifacedigital_disable_interrupts();
pifacedigital_close(0);

Parameters

data	Points to where to store the value of the 8-bit input states.
timeout	Maximum ms to wait for input, -1 for forever
hw_addr	The hardware address (configure with jumpers: JP1 and JP2).

Returns

int Status, 1 if successful, 0 on timeout and -1 on error.

void pifacedigital_write_bit	(	uint8_t	data,
		uint8_t	bit_num,
		uint8_t	reg,
		uint8_t	hw_addr
	)

Writes to a bit on a register on PiFace Digital.

Example (write 1 to bit 3 of OUTPUT on PiFace Digital 0):

pifacedigital_write_bit(1, 3, OUTPUT, 0);

Parameters

data	The value to write.
bit_num	The bit number to read from.
reg	The register to write to (example: INPUT, OUTPUT, GPPUB).
hw_addr	The hardware address (configure with jumpers: JP1 and JP2).

void pifacedigital_write_reg	(	uint8_t	data,
		uint8_t	reg,
		uint8_t	hw_addr
	)

Writes to a register on PiFace Digital.

Example (write 0xaa to OUTPUT on PiFace Digital 0):

pifacedigital_write_reg(0xaa, OUTPUT, 0);

Parameters

data	The byte to write.
reg	The register to write to (example: INPUT, OUTPUT, GPPUB).
hw_addr	The hardware address (configure with jumpers: JP1 and JP2).