parent
3d9fda3629
commit
60797c8439
|
@ -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);
|
||||
}
|
||||
}
|
|
@ -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
|
Loading…
Reference in New Issue