diff options
Diffstat (limited to 'drivers/avr')
-rwxr-xr-x | drivers/avr/i2c_slave.c | 100 | ||||
-rwxr-xr-x | drivers/avr/i2c_slave.h | 19 |
2 files changed, 119 insertions, 0 deletions
diff --git a/drivers/avr/i2c_slave.c b/drivers/avr/i2c_slave.c new file mode 100755 index 0000000000..3edf85b12b --- /dev/null +++ b/drivers/avr/i2c_slave.c @@ -0,0 +1,100 @@ +/* Library made by: g4lvanix + * Github repository: https://github.com/g4lvanix/I2C-slave-lib + */ + +#include <avr/io.h> +#include <util/twi.h> +#include <avr/interrupt.h> + +#include "i2c_slave.h" + +void i2c_init(uint8_t address){ + // load address into TWI address register + TWAR = (address << 1); + // set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt + TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN); +} + +void i2c_stop(void){ + // clear acknowledge and enable bits + TWCR &= ~( (1<<TWEA) | (1<<TWEN) ); +} + +ISR(TWI_vect){ + + // temporary stores the received data + uint8_t data; + + // own address has been acknowledged + if( (TWSR & 0xF8) == TW_SR_SLA_ACK ){ + buffer_address = 0xFF; + // clear TWI interrupt flag, prepare to receive next byte and acknowledge + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); + } + else if( (TWSR & 0xF8) == TW_SR_DATA_ACK ){ // data has been received in slave receiver mode + + // save the received byte inside data + data = TWDR; + + // check wether an address has already been transmitted or not + if(buffer_address == 0xFF){ + + buffer_address = data; + + // clear TWI interrupt flag, prepare to receive next byte and acknowledge + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); + } + else{ // if a databyte has already been received + + // store the data at the current address + rxbuffer[buffer_address] = data; + + // increment the buffer address + buffer_address++; + + // if there is still enough space inside the buffer + if(buffer_address < 0xFF){ + // clear TWI interrupt flag, prepare to receive next byte and acknowledge + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); + } + else{ + // Don't acknowledge + TWCR &= ~(1<<TWEA); + // clear TWI interrupt flag, prepare to receive last byte. + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEN); + } + } + } + else if( (TWSR & 0xF8) == TW_ST_DATA_ACK ){ // device has been addressed to be a transmitter + + // copy data from TWDR to the temporary memory + data = TWDR; + + // if no buffer read address has been sent yet + if( buffer_address == 0xFF ){ + buffer_address = data; + } + + // copy the specified buffer address into the TWDR register for transmission + TWDR = txbuffer[buffer_address]; + // increment buffer read address + buffer_address++; + + // if there is another buffer address that can be sent + if(buffer_address < 0xFF){ + // clear TWI interrupt flag, prepare to send next byte and receive acknowledge + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); + } + else{ + // Don't acknowledge + TWCR &= ~(1<<TWEA); + // clear TWI interrupt flag, prepare to receive last byte. + TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEN); + } + + } + else{ + // if none of the above apply prepare TWI to be addressed again + TWCR |= (1<<TWIE) | (1<<TWEA) | (1<<TWEN); + } +} diff --git a/drivers/avr/i2c_slave.h b/drivers/avr/i2c_slave.h new file mode 100755 index 0000000000..3fda7f8c09 --- /dev/null +++ b/drivers/avr/i2c_slave.h @@ -0,0 +1,19 @@ +/* Library made by: g4lvanix + * Github repository: https://github.com/g4lvanix/I2C-slave-lib + + Info: Inititate the library by giving the required address. + Read or write to the necessary buffer according to the opperation. + */ + +#ifndef I2C_SLAVE_H +#define I2C_SLAVE_H + +volatile uint8_t buffer_address; +volatile uint8_t txbuffer[0xFF]; +volatile uint8_t rxbuffer[0xFF]; + +void i2c_init(uint8_t address); +void i2c_stop(void); +ISR(TWI_vect); + +#endif // I2C_SLAVE_H |