Init and Config Functions

These functions handle initialization and configuration. More...

Functions
int	mcp2515_bitrate_simplified (pi_mcp2515_t *pi_mcp2515, uint16_t baud_rate_kbps)
	A simplified bitrate setting function.
int	mcp2515_bitrate_full_optional (pi_mcp2515_t *pi_mcp2515, uint16_t baud_rate_kbps, uint8_t sjw, uint8_t prescaler, uint8_t prseg_tqps, uint8_t phseg_tqps1, uint8_t phseg_tqps2, bool sof, bool wakfil, bool sam, bool btlmode)
	Configure the bitrate and all other CNF register stored parameters.
int	mcp2515_cnf_set (pi_mcp2515_t *pi_mcp2515, uint8_t cnf1, uint8_t cnf2, uint8_t cnf3)
	Set the values of all CNF register.
uint8_t	mcp2515_cnf_get (pi_mcp2515_t *pi_mcp2515, uint8_t cnf)
	Get the value of a CNF register.
int	mcp2515_init (pi_mcp2515_t **pi_mcp2515, uint8_t spi_channel, uint8_t tx_pin, uint8_t rx_pin, uint8_t sck_pin, uint8_t cs_pin, uint32_t spi_clock, uint8_t osc_mhz)
	Setup and prepare a pi_mcp2515_t structure based on the parameters provided.
void	mcp2515_conf_spi_devpath (pi_mcp2515_t *pi_mcp2515, char *spidev_path)
	Override the default path for the spi device (ex /dev/spi0).
void	mcp2515_conf_gpio_devpath (pi_mcp2515_t *pi_mcp2515, char *gpiodev_path)
	Override the default path for the gpio device (ex /dev/gpio0).
void	mcp2515_free (pi_mcp2515_t *pi_mcp2515)
	Cleanup after everything.

Detailed Description

These functions handle initialization and configuration.

Function Documentation

mcp2515_bitrate_full_optional()

int mcp2515_bitrate_full_optional	(	pi_mcp2515_t *	pi_mcp2515,
		uint16_t	baud_rate_kbps,
		uint8_t	sjw,
		uint8_t	prescaler,
		uint8_t	prseg_tqps,
		uint8_t	phseg_tqps1,
		uint8_t	phseg_tqps2,
		bool	sof,
		bool	wakfil,
		bool	sam,
		bool	btlmode )

Configure the bitrate and all other CNF register stored parameters.

This function accepts all possible configurable options, while mcp2515_bitrate_simplified can be used for a simplified process.

TODO first draft. Test/validate/fix. Make sure this is right.

Parameters

pi_mcp2515	the piMCP2515 handle.
baud_rate_kbps	the baud rate to use in kbps. Commonly either 500 or 1000.
sjw	the synchronization jump width in Tqs (1-4).
prescaler	the prescaler divisor (0-63)
prseg_tqps	the prop segment Tqs/segment
phseg_tqps1	the phase segment 1 Tqs/segment
phseg_tqps2	the phase segment 2 Tqs/segment
sof	if start-of-frame signal is enabled.
wakfil	if wakeup filter should be enabled.
sam	is bus line should be sampled 3 times at sample point (otherwise it is sampled once).
btlmode	if BTLMODE is enabled. true: PS2 length is determined by PHSEG2[2:0] (PHSEG2 values originate from phseg_tqps2). false: PS2 length is the greater of PS1 and IPT (2 Tqs)

Returns

zero if success, otherwise non-zero.

mcp2515_bitrate_simplified()

int mcp2515_bitrate_simplified	(	pi_mcp2515_t *	pi_mcp2515,
		uint16_t	baud_rate_kbps )

A simplified bitrate setting function.

Parameters

pi_mcp2515	the piMCP2515 handle.
baud_rate_kbps	the baud rate to use in kbps. Commonly either 500 or 1000.

Returns

zero if success, otherwise non-zero.

mcp2515_cnf_get()

uint8_t mcp2515_cnf_get	(	pi_mcp2515_t *	pi_mcp2515,
		uint8_t	cnf )

Get the value of a CNF register.

Parameters

pi_mcp2515	the piMCP2515 handle.
cnf	The CNF register index such that cnf being 1 will fetch from CNF1, etc.

Returns

The value of the register.

mcp2515_cnf_set()

int mcp2515_cnf_set	(	pi_mcp2515_t *	pi_mcp2515,
		uint8_t	cnf1,
		uint8_t	cnf2,
		uint8_t	cnf3 )

Set the values of all CNF register.

Parameters

pi_mcp2515	the piMCP2515 handle.
cnf1	the value to use for the CNF1 register.
cnf2	the value to use for the CNF2 register.
cnf3	the value to use for the CNF3 register.

Returns

zero if success, otherwise non-zero.

mcp2515_conf_gpio_devpath()

void mcp2515_conf_gpio_devpath	(	pi_mcp2515_t *	pi_mcp2515,
		char *	gpiodev_path )

Override the default path for the gpio device (ex /dev/gpio0).

NOOP unless built for spidev.

This function generally will not need to be used as the library should be able to figure out the device patch. Use this only if it can't in your use case. If it is unable to find the path for you, please open an issue on the project with the details so that can be fixed.

Parameters

pi_mcp2515	the piMCP2515 handle.
gpiodev_path	the alternate GPIO device path to use.

mcp2515_conf_spi_devpath()

void mcp2515_conf_spi_devpath	(	pi_mcp2515_t *	pi_mcp2515,
		char *	spidev_path )

Override the default path for the spi device (ex /dev/spi0).

NOOP unless built for spidev.

This function generally will not need to be used as the library should be able to figure out the device patch. Use this only if it can't in your use case. If it is unable to find the path for you, please open an issue on the project with the details so that can be fixed.

Parameters

pi_mcp2515	the piMCP2515 handle.
spidev_path	the alternate SPI device path to use.

mcp2515_free()

void mcp2515_free

(

pi_mcp2515_t *

pi_mcp2515

)

Cleanup after everything.

Parameters

pi_mcp2515

the piMCP2515 handle.

mcp2515_init()

int mcp2515_init	(	pi_mcp2515_t **	pi_mcp2515,
		uint8_t	spi_channel,
		uint8_t	tx_pin,
		uint8_t	rx_pin,
		uint8_t	sck_pin,
		uint8_t	cs_pin,
		uint32_t	spi_clock,
		uint8_t	osc_mhz )

Setup and prepare a pi_mcp2515_t structure based on the parameters provided.

This will still require one of the bitrate setting functions or mcp2515_cnf_set to be used to set up the CNF registers.

Parameters

pi_mcp2515	the piMCP2515 handle.
spi_channel	the SPI channel to use which may be 0 or 1.
sck_pin	the SCK pin for SPI communication.
tx_pin	the TX pin for SPI communication.
rx_pin	the RX pin for SPI communication.
spi_clock	the frequency to use for SPI communication in Hz.
osc_mhz	the frequency of the MCP2515 oscillator in MHz.
cs_pin	the GPIO pin to use for SPI chip select.

Returns

zero if success, otherwise non-zero