Two wire interface. More...

Collaboration diagram for AT91 Two Wire Interface:

Defines
#define	TWI_PIO_ASR PIOA_ASR
#define	TWI_PIO_PDR PIOA_PDR
#define	TWI_PIO_MDER PIOA_MDER
Functions
int	NutTwiMasterTranceive (NUTTWIBUS bus, uint8_t sla, const void txdata, uint16_t txlen, void *rxdata, uint16_t rxsiz, uint32_t tmo)
	Transmit and/or receive data as a master.
int	NutTwiMasterRegRead (NUTTWIBUS bus, uint8_t sla, uint32_t iadr, uint8_t iadrlen, void rxdata, uint16_t rxsiz, uint32_t tmo)
	Receive data as a master from a device having internal addressable registers.
int	NutTwiMasterRegWrite (NUTTWIBUS bus, uint8_t sla, uint32_t iadr, uint8_t iadrlen, const void txdata, uint16_t txsiz, uint32_t tmo)
	Transmit data as a master to a device having internal addressable registers.
int	NutTwiMasterError (NUTTWIBUS *bus)
	Get last master mode error.
int	NutTwiSlaveListen (NUTTWIBUS bus, uint8_t sla, void *rxdata, uint16_t rxsiz, uint32_t tmo)
	Listen for incoming data from a master.
int	NutTwiSlaveRespond (NUTTWIBUS bus, void txdata, uint16_t txlen, uint32_t tmo)
	Send response to a master.
int	NutTwiSlaveError (NUTTWIBUS *bus)
	Get last slave mode error.
uint16_t	NutTwiIndexes (NUTTWIBUS *bus, uint8_t idx)
	Get last transfer results.
int	NutTwiSetSpeed (NUTTWIBUS *bus, uint32_t speed)
	Set Speed of I2C Interface.
int	NutTwiGetSpeed (NUTTWIBUS *bus)
	Request Current Speed of I2C Interface.
int	NutTwiIOCtl (NUTTWIBUS bus, int req, void conf)
	Perform TWI control functions.
int	At91TwiInit (void)
	Initialize TWI interface hardware.
int	NutRegisterTwiBus (NUTTWIBUS *bus, uint8_t sla)
	Initialize TWI interface bus.
int	NutDestroyTwiBus (NUTTWIBUS *bus)
Variables
NUTTWIBUS	At91TwiBus
	TWI/I2C bus structure.
TWI Control Register
#define	TWI_CR_OFF 0x00000000
	Control register offset.
#define	TWI_CR (TWI_BASE + TWI_CR_OFF)
	Control register address.
#define	TWI_START 0x00000001
	Send start condition.
#define	TWI_STOP 0x00000002
	Send stop condition.
#define	TWI_MSEN 0x00000004
	Enable master mode.
#define	TWI_MSDIS 0x00000008
	Disable master mode.
#define	TWI_SVEN 0x00000010
	Enable slave mode.
#define	TWI_SVDIS 0x00000020
	Disable slave mode.
#define	TWI_SWRST 0x00000080
	Software reset.
TWI Master Mode Register
#define	TWI_MMR_OFF 0x00000004
	Master mode register offset.
#define	TWI_MMR (TWI_BASE + TWI_MMR_OFF)
	Master mode register address.
#define	TWI_IADRSZ 0x00000300
	Internal device address size mask.
#define	TWI_IADRSZ_NONE 0x00000000
	No internal device address.
#define	TWI_IADRSZ_1BYTE 0x00000100
	One byte internal device address.
#define	TWI_IADRSZ_2BYTE 0x00000200
	Two byte internal device address.
#define	TWI_IADRSZ_3BYTE 0x00000300
	Three byte internal device address.
#define	TWI_MREAD 0x00001000
	Master read direction.
#define	TWI_DADR 0x007F0000
	Device address mask.
#define	TWI_DADR_LSB 16
	Device address LSB.
TWI Slave Mode Register
#define	TWI_SMR_OFF 0x00000008
	Slave mode register offset.
#define	TWI_SMR (TWI_BASE + TWI_SMR_OFF)
	Slave mode register address.
#define	TWI_SADR 0x007F0000
	Slave address mask.
#define	TWI_SADR_LSB 16
	Slave address LSB.
TWI Internal Address Register
#define	TWI_IADRR_OFF 0x0000000C
	Internal address register offset.
#define	TWI_IADRR (TWI_BASE + TWI_IADRR_OFF)
	Internal address register address.
#define	TWI_IADR 0x00FFFFFF
	Internal address mask.
#define	TWI_IADR_LSB 0
	Internal address LSB.
TWI Clock Waveform Generator Register
#define	TWI_CWGR_OFF 0x00000010
	Clock waveform generator register offset.
#define	TWI_CWGR (TWI_BASE + TWI_CWGR_OFF)
	Clock waveform generator register address.
#define	TWI_CLDIV 0x000000FF
	Clock low divider mask.
#define	TWI_CLDIV_LSB 0
	Clock low divider LSB.
#define	TWI_CHDIV 0x0000FF00
	Clock high divider mask.
#define	TWI_CHDIV_LSB 8
	Clock high divider LSB.
#define	TWI_CKDIV 0x00070000
	Clock divider mask.
#define	TWI_CKDIV_LSB 16
	Clock divider LSB.
TWI Status and Interrupt Registers
#define	TWI_SR_OFF 0x00000020
	Status register offset.
#define	TWI_SR (TWI_BASE + TWI_SR_OFF)
	Status register address.
#define	TWI_IER_OFF 0x00000024
	Interrupt enable register offset.
#define	TWI_IER (TWI_BASE + TWI_IER_OFF)
	Interrupt enable register address.
#define	TWI_IDR_OFF 0x00000028
	Interrupt disable register offset.
#define	TWI_IDR (TWI_BASE + TWI_IDR_OFF)
	Interrupt disable register address.
#define	TWI_IMR_OFF 0x0000002C
	Interrupt mask register offset.
#define	TWI_IMR (TWI_BASE + TWI_IMR_OFF)
	Interrupt mask register address.
#define	TWI_TXCOMP 0x00000001
	Transmission completed.
#define	TWI_RXRDY 0x00000002
	Receive holding register ready.
#define	TWI_TXRDY 0x00000004
	Transmit holding register ready.
#define	TWI_SVREAD 0x00000008
	Slave read.
#define	TWI_SVACC 0x00000010
	Slave access.
#define	TWI_GACC 0x00000020
	General call access.
#define	TWI_OVRE 0x00000040
	Overrun error.
#define	TWI_NACK 0x00000100
	Not acknowledged.
#define	TWI_ARBLST 0x00000200
	Arbitration lost.
#define	TWI_SCLWS 0x00000400
	Clock wait state.
#define	TWI_EOSACC 0x00000800
	End of slave access.
TWI Receive Holding Register
#define	TWI_RHR_OFF 0x00000030
	Receive holding register offset.
#define	TWI_RHR (TWI_BASE + TWI_RHR_OFF)
	Receive holding register address.
TWI Transmit Holding Register
#define	TWI_THR_OFF 0x00000034
	Transmit holding register offset.
#define	TWI_THR (TWI_BASE + TWI_THR_OFF)
	Transmit holding register address.

Detailed Description

Two wire interface.

Define Documentation

#define TWI_CR_OFF 0x00000000

Control register offset.

#define TWI_CR (TWI_BASE + TWI_CR_OFF)

Control register address.

Referenced by At91TwiInit(), NutTwiMasterRegRead(), and NutTwiMasterTranceive().

#define TWI_START 0x00000001

Send start condition.

Referenced by NutTwiMasterRegRead(), and NutTwiMasterTranceive().

#define TWI_STOP 0x00000002

Send stop condition.

Referenced by NutTwiMasterRegRead(), and NutTwiMasterTranceive().

#define TWI_MSEN 0x00000004

Enable master mode.

Referenced by At91TwiInit().

#define TWI_MSDIS 0x00000008

Disable master mode.

#define TWI_SVEN 0x00000010

Enable slave mode.

#define TWI_SVDIS 0x00000020

Disable slave mode.

Referenced by At91TwiInit().

#define TWI_SWRST 0x00000080

Software reset.

Referenced by At91TwiInit().

#define TWI_MMR_OFF 0x00000004

Master mode register offset.

#define TWI_MMR (TWI_BASE + TWI_MMR_OFF)

Master mode register address.

Referenced by NutTwiMasterRegRead(), NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_IADRSZ 0x00000300

Internal device address size mask.

#define TWI_IADRSZ_NONE 0x00000000

No internal device address.

#define TWI_IADRSZ_1BYTE 0x00000100

One byte internal device address.

#define TWI_IADRSZ_2BYTE 0x00000200

Two byte internal device address.

#define TWI_IADRSZ_3BYTE 0x00000300

Three byte internal device address.

#define TWI_MREAD 0x00001000

Master read direction.

Referenced by NutTwiMasterRegRead(), and NutTwiMasterTranceive().

#define TWI_DADR 0x007F0000

Device address mask.

#define TWI_DADR_LSB 16

Device address LSB.

Referenced by NutTwiMasterRegRead(), NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_SMR_OFF 0x00000008

Slave mode register offset.

#define TWI_SMR (TWI_BASE + TWI_SMR_OFF)

Slave mode register address.

#define TWI_SADR 0x007F0000

Slave address mask.

#define TWI_SADR_LSB 16

Slave address LSB.

#define TWI_IADRR_OFF 0x0000000C

Internal address register offset.

#define TWI_IADRR (TWI_BASE + TWI_IADRR_OFF)

Internal address register address.

Referenced by NutTwiMasterRegRead(), and NutTwiMasterRegWrite().

#define TWI_IADR 0x00FFFFFF

Internal address mask.

#define TWI_IADR_LSB 0

Internal address LSB.

#define TWI_CWGR_OFF 0x00000010

Clock waveform generator register offset.

#define TWI_CWGR (TWI_BASE + TWI_CWGR_OFF)

Clock waveform generator register address.

Referenced by NutTwiGetSpeed(), and NutTwiSetSpeed().

#define TWI_CLDIV 0x000000FF

Clock low divider mask.

#define TWI_CLDIV_LSB 0

Clock low divider LSB.

#define TWI_CHDIV 0x0000FF00

Clock high divider mask.

#define TWI_CHDIV_LSB 8

Clock high divider LSB.

#define TWI_CKDIV 0x00070000

Clock divider mask.

#define TWI_CKDIV_LSB 16

Clock divider LSB.

#define TWI_SR_OFF 0x00000020

Status register offset.

#define TWI_SR (TWI_BASE + TWI_SR_OFF)

Status register address.

#define TWI_IER_OFF 0x00000024

Interrupt enable register offset.

#define TWI_IER (TWI_BASE + TWI_IER_OFF)

Interrupt enable register address.

Referenced by NutTwiMasterRegRead(), NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_IDR_OFF 0x00000028

Interrupt disable register offset.

#define TWI_IDR (TWI_BASE + TWI_IDR_OFF)

Interrupt disable register address.

Referenced by At91TwiInit(), NutTwiMasterRegRead(), NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_IMR_OFF 0x0000002C

Interrupt mask register offset.

#define TWI_IMR (TWI_BASE + TWI_IMR_OFF)

Interrupt mask register address.

#define TWI_TXCOMP 0x00000001

Transmission completed.

#define TWI_RXRDY 0x00000002

Receive holding register ready.

Referenced by NutTwiMasterRegRead(), and NutTwiMasterTranceive().

#define TWI_TXRDY 0x00000004

Transmit holding register ready.

Referenced by NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_SVREAD 0x00000008

Slave read.

#define TWI_SVACC 0x00000010

Slave access.

#define TWI_GACC 0x00000020

General call access.

#define TWI_OVRE 0x00000040

Overrun error.

#define TWI_NACK 0x00000100

Not acknowledged.

#define TWI_ARBLST 0x00000200

Arbitration lost.

#define TWI_SCLWS 0x00000400

Clock wait state.

#define TWI_EOSACC 0x00000800

End of slave access.

#define TWI_RHR_OFF 0x00000030

Receive holding register offset.

#define TWI_RHR (TWI_BASE + TWI_RHR_OFF)

Receive holding register address.

#define TWI_THR_OFF 0x00000034

Transmit holding register offset.

#define TWI_THR (TWI_BASE + TWI_THR_OFF)

Transmit holding register address.

Referenced by NutTwiMasterRegWrite(), and NutTwiMasterTranceive().

#define TWI_PIO_ASR PIOA_ASR

Referenced by At91TwiInit().

#define TWI_PIO_PDR PIOA_PDR

Referenced by At91TwiInit().

#define TWI_PIO_MDER PIOA_MDER

Referenced by At91TwiInit().

Function Documentation

int NutTwiMasterTranceive	(	NUTTWIBUS *	bus,
		uint8_t	sla,
		const void *	txdata,
		uint16_t	txlen,
		void *	rxdata,
		uint16_t	rxsiz,
		uint32_t	tmo
	)

Transmit and/or receive data as a master.

The two-wire serial interface must have been initialized by calling TwInit() before this function can be used.

Parameters:

sla	Slave address of the destination. This slave address must be specified as a 7-bit address. For example, the PCF8574A may be configured to slave addresses from 0x38 to 0x3F.
txdata	Points to the data to transmit. Ignored, if the number of data bytes to transmit is zero.
txlen	Number of data bytes to transmit. If zero, then the interface will not send any data to the slave device and will directly enter the master receive mode.
rxdata	Points to a buffer, where the received data will be stored. Ignored, if the maximum number of bytes to receive is zero.
rxsiz	Maximum number of bytes to receive. Set to zero, if no bytes are expected from the slave device.
tmo	Timeout in milliseconds. To disable timeout, set this parameter to NUT_WAIT_INFINITE.

Returns:: The number of bytes received, -1 in case of an error or timeout.

References _NUTTWIBUS::bus_icb, _NUTTWIBUS::bus_mutex, NutEventPost(), NutEventWait(), outr, rc, _NUTTWIICB::tw_mm_buf, _NUTTWIICB::tw_mm_err, _NUTTWIICB::tw_mm_error, _NUTTWIICB::tw_mm_idx, _NUTTWIICB::tw_mm_len, _NUTTWIICB::tw_mm_mtx, TWERR_IF_LOCKED, TWERR_TIMEOUT, TWI_CR, TWI_DADR_LSB, TWI_IDR, TWI_IER, TWI_MMR, TWI_MREAD, TWI_RXRDY, TWI_START, TWI_STOP, TWI_THR, and TWI_TXRDY.

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int NutTwiMasterRegRead	(	NUTTWIBUS *	bus,
		uint8_t	sla,
		uint32_t	iadr,
		uint8_t	iadrlen,
		void *	rxdata,
		uint16_t	rxsiz,
		uint32_t	tmo
	)

Receive data as a master from a device having internal addressable registers.

The two-wire serial interface must have been initialized by calling TwInit() before this function can be used.

Parameters:

sla	Slave address of the destination. This slave address must be specified as a 7-bit address. For example, the PCF8574A may be configured to slave addresses from 0x38 to 0x3F.
iadr	Address send to the device to access certain registers or memory addresses of it.
iadrlen	Number of bytes to send as address, maximum 3 bytes are supported from AT91SAM7
rxdata	Points to a buffer, where the received data will be stored.
rxsiz	Maximum number of bytes to receive.
tmo	Timeout in milliseconds. To disable timeout, set this parameter to NUT_WAIT_INFINITE.

Returns:: The number of bytes received, -1 in case of an error or timeout.

References _NUTTWIBUS::bus_icb, _NUTTWIBUS::bus_mutex, NutEventPost(), NutEventWait(), outr, rc, _NUTTWIICB::tw_mm_buf, _NUTTWIICB::tw_mm_err, _NUTTWIICB::tw_mm_error, _NUTTWIICB::tw_mm_idx, _NUTTWIICB::tw_mm_len, _NUTTWIICB::tw_mm_mtx, TWERR_IF_LOCKED, TWERR_TIMEOUT, TWI_CR, TWI_DADR_LSB, TWI_IADRR, TWI_IDR, TWI_IER, TWI_MMR, TWI_MREAD, TWI_RXRDY, TWI_START, and TWI_STOP.

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int NutTwiMasterRegWrite	(	NUTTWIBUS *	bus,
		uint8_t	sla,
		uint32_t	iadr,
		uint8_t	iadrlen,
		const void *	txdata,
		uint16_t	txsiz,
		uint32_t	tmo
	)

Transmit data as a master to a device having internal addressable registers.

The two-wire serial interface must have been initialized by calling TwInit() before this function can be used.

Parameters:

sla	Slave address of the destination. This slave address must be specified as a 7-bit address. For example, the PCF8574A may be configured to slave addresses from 0x38 to 0x3F.
iadr	Address send to the device to access certain registers or memory addresses of it.
iadrlen	Number of bytes to send as address, maximum 3 bytes are supported from AT91SAM7
txdata	Points to a buffer, where the data to transmit will be stored.
txsiz	Maximum number of bytes to transmit.
tmo	Timeout in milliseconds. To disable timeout, set this parameter to NUT_WAIT_INFINITE.

Returns:: The number of bytes transmitted, -1 in case of an error or timeout. Number could be less if slave end transmission with NAK.

References _NUTTWIBUS::bus_icb, _NUTTWIBUS::bus_mutex, NutEventPost(), NutEventWait(), outb, outr, rc, _NUTTWIICB::tw_mm_buf, _NUTTWIICB::tw_mm_err, _NUTTWIICB::tw_mm_error, _NUTTWIICB::tw_mm_idx, _NUTTWIICB::tw_mm_len, _NUTTWIICB::tw_mm_mtx, TWERR_IF_LOCKED, TWERR_TIMEOUT, TWI_DADR_LSB, TWI_IADRR, TWI_IDR, TWI_IER, TWI_MMR, TWI_THR, and TWI_TXRDY.

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int NutTwiMasterError ( NUTTWIBUS * bus )

Get last master mode error.

You may call this function to determine the specific cause of an error after twi transaction failed.

References _NUTTWIBUS::bus_icb, rc, and _NUTTWIICB::tw_mm_error.

int NutTwiSlaveListen	(	NUTTWIBUS *	bus,
		uint8_t *	sla,
		void *	rxdata,
		uint16_t	rxsiz,
		uint32_t	tmo
	)

Listen for incoming data from a master.

If this function returns without error, the bus is blocked. The caller must immediately process the request and return a response by calling TwSlaveRespond().

Note:: Slave mode is not implemented in the AT91 driver. Thus the function always returns -1.

Parameters:

sla	Points to a byte variable, which receives the slave address sent by the master. This can be used by the caller to determine whether the the interface has been addressed by a general call or its individual address.
rxdata	Points to a data buffer where the received data bytes are stored.
rxsiz	Specifies the maximum number of data bytes to receive.
tmo	Timeout in milliseconds. To disable timeout, set this parameter to NUT_WAIT_INFINITE.

Returns:: The number of bytes received, -1 in case of an error or timeout.

int NutTwiSlaveRespond	(	NUTTWIBUS *	bus,
		void *	txdata,
		uint16_t	txlen,
		uint32_t	tmo
	)

Send response to a master.

This function must be called as soon as possible after TwSlaveListen() returned successfully, even if no data needs to be returned. Not doing so will completely block the bus.

Note:: Slave mode is not implemented in the AT91 driver. Thus the function always returns -1.

Parameters:

txdata	Points to the data to transmit. Ignored, if the number of bytes to transmit is zero.
txlen	Number of data bytes to transmit.
tmo	Timeout in milliseconds. To disable timeout, set this parameter to NUT_WAIT_INFINITE.

Returns:: The number of bytes transmitted, -1 in case of an error or timeout.

int NutTwiSlaveError ( NUTTWIBUS * bus )

Get last slave mode error.

You may call this function to determine the specific cause of an error after TwSlaveListen() or TwSlaveRespond() failed.

Returns:: Error code or 0 if no error occurred.

Note:: Slave mode is not implemented in the AT91 driver. Thus the function always returns TWERR_BUS.

References TWERR_BUS.

uint16_t NutTwiIndexes	(	NUTTWIBUS *	bus,
		uint8_t	idx
	)

Get last transfer results.

Todo:: Do we really need this. It may not work with competing threads.

You may call this function to determine how many bytes where transferred before the twi transaction failed.

References _NUTTWIBUS::bus_icb, _NUTTWIICB::tw_mm_error, and _NUTTWIICB::tw_mm_len.

int NutTwiSetSpeed	(	NUTTWIBUS *	bus,
		uint32_t	speed
	)

Set Speed of I2C Interface.

Setup Interface Speed

References NULL, NUT_HWCLK_PERIPHERAL, NutClockGet, outr, rc, and TWI_CWGR.

Referenced by NutRegisterTwiBus(), and NutTwiIOCtl().

int NutTwiGetSpeed ( NUTTWIBUS * bus )

Request Current Speed of I2C Interface.

Returns:: 0..400000 for speed, -1 in case of error.

References inr, NutGetCpuClock(), rc, and TWI_CWGR.

Referenced by NutTwiIOCtl().

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int NutTwiIOCtl	(	NUTTWIBUS *	bus,
		int	req,
		void *	conf
	)

Perform TWI control functions.

Parameters:

req	Requested control function. May be set to one of the following constants: TWI_SETSPEED, if conf points to an uint32_t value containing the bitrate. TWI_GETSPEED, if conf points to an uint32_t value receiving the current bitrate.
conf	Points to a buffer that contains any data required for the given control function or receives data from that function.

Returns:: 0 on success, -1 otherwise.

Note:: Timeout is limited to the granularity of the system timer.

References _NUTTWIBUS::bus_icb, NutTwiGetSpeed(), NutTwiSetSpeed(), rc, _NUTTWIICB::tw_mm_sla, TWI_GETSLAVEADDRESS, TWI_GETSPEED, TWI_GETSTATUS, TWI_SETSLAVEADDRESS, TWI_SETSPEED, and TWI_SETSTATUS.

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int At91TwiInit ( void )

Initialize TWI interface hardware.

References _BV, outr, PMC_PCER, rc, TWI_CR, TWI_ID, TWI_IDR, TWI_MSEN, TWI_PIO_ASR, TWI_PIO_MDER, TWI_PIO_PDR, TWI_SVDIS, and TWI_SWRST.

int NutRegisterTwiBus	(	NUTTWIBUS *	bus,
		uint8_t	sla
	)

Initialize TWI interface bus.

The specified slave address is not used here as we don't support twi-slave on AT91SAM7X

Note:: This function is only available on AT91SAM7xxxx systems.

Parameters:

sla	Slave address, must be specified as a 7-bit address, always lower than 128.

References _NUTTWIBUS::bus_icb, _NUTTWIBUS::bus_initbus, _NUTTWIBUS::bus_mutex, _NUTTWIBUS::bus_sig_ev, memset(), NULL, NUT_IRQMODE_LEVEL, NutEventPost(), NutHeapAlloc, NutIrqEnable(), NutIrqSetMode(), NutRegisterIrqHandler(), NutTwiSetSpeed(), and rc.

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int NutDestroyTwiBus ( NUTTWIBUS * bus )

References _NUTTWIBUS::bus_icb, _NUTTWIBUS::bus_sig_ev, NutHeapFree, and NutIrqDisable().

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Variable Documentation

NUTTWIBUS At91TwiBus

Initial value:

 {
    TWI_CR,      
   &sig_TWI,     
    NULL,        
    NULL,        
    NULL,        
    0,           
    0,           
    At91TwiInit, 
    NULL,        
}

TWI/I2C bus structure.

Defines

Functions

Variables

TWI Control Register

TWI Master Mode Register

TWI Slave Mode Register

TWI Internal Address Register

TWI Clock Waveform Generator Register

TWI Status and Interrupt Registers

TWI Receive Holding Register

TWI Transmit Holding Register

Detailed Description

Define Documentation

Function Documentation

Variable Documentation