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TWI related subroutines (as a controller (master)). This code is a part of pAVRlib.
This program works only on AVRs which have a TWI module.
Subroutines
void TWI_INITIALIZE() (in: (none), out: (none))
initializes TWI Module.
You must define F_CPU and F_SCL before you call this routine.
unsigned int TWI_SEND_S() (in: (none), out: r25)
sends a start bit. This returns r25:r24. A status code of TWI is stored in r25. r24 is unchanged. See reference manual from Atmel (Microchip) for more details.
void TWI_SEND_P() (in: (none), out: (none))
sends a stop bit.
unsigned int TWI_SEND(char data) (in: r24, out: r25:r24)
sends a byte data via TWI.
This returns r25:r24. A status code of TWI is stored in r25.
r24 is unchanged.
unsigned int TWI_SEND_SLA_R(char address) (in: r24, out: r25:r24)
address is a target (slave) address (7 bits).
This returns r25:r24. A status code of TWI is stored in r25.
r24 is unchanged.
unsigned int TWI_SEND_SLA_W(char address) (in: r24, out: r25:r24)
address is a target (slave) address (7 bits).
This returns r25:r24. A status code of TWI is stored in r25.
r24 is unchanged.
unsigned int TWI_RECV_ACK() (in: (none), out: r25:r24)
receives a byte and returns an ACK. The received data will be stored in r24 and a result code of TWI in r25.
unsigned int TWI_RECV_NACK() (in: (none), out: r25:r24)
receives a byte and returns a NACK. The received data will be stored in r24 and a result code of TWI in r25.
Example
examples/twi-controller-test.asm
This program scans I²C devices and shows if a device on each address exists.
To compile this file, the following files are required (These files are parts of the pAVRlib).
See also: examples/README.org