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Diffstat (limited to 'keyboards/m0lly/i2c.c')
| -rw-r--r-- | keyboards/m0lly/i2c.c | 166 |
1 files changed, 0 insertions, 166 deletions
diff --git a/keyboards/m0lly/i2c.c b/keyboards/m0lly/i2c.c deleted file mode 100644 index cd2b835d50..0000000000 --- a/keyboards/m0lly/i2c.c +++ /dev/null @@ -1,166 +0,0 @@ -#include <util/twi.h> -#include <avr/io.h> -#include <stdlib.h> -#include <avr/interrupt.h> -#include <util/twi.h> -#include <stdbool.h> -#include "i2c.h" - -#ifdef USE_I2C - -// Limits the amount of we wait for any one i2c transaction. -// Since were running SCL line 100kHz (=> 10μs/bit), and each transactions is -// 9 bits, a single transaction will take around 90μs to complete. -// -// (F_CPU/SCL_CLOCK) => # of μC cycles to transfer a bit -// poll loop takes at least 8 clock cycles to execute -#define I2C_LOOP_TIMEOUT (9+1)*(F_CPU/SCL_CLOCK)/8 - -#define BUFFER_POS_INC() (slave_buffer_pos = (slave_buffer_pos+1)%SLAVE_BUFFER_SIZE) - -volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE]; - -static volatile uint8_t slave_buffer_pos; -static volatile bool slave_has_register_set = false; - -// Wait for an i2c operation to finish -inline static -void i2c_delay(void) { - uint16_t lim = 0; - while(!(TWCR & (1<<TWINT)) && lim < I2C_LOOP_TIMEOUT) - lim++; - - // easier way, but will wait slightly longer - // _delay_us(100); -} - -// Setup twi to run at 100kHz -void i2c_master_init(void) { - // no prescaler - TWSR = 0; - // Set TWI clock frequency to SCL_CLOCK. Need TWBR>10. - // Check datasheets for more info. - TWBR = ((F_CPU/SCL_CLOCK)-16)/2; -} - -// Start a transaction with the given i2c slave address. The direction of the -// transfer is set with I2C_READ and I2C_WRITE. -// returns: 0 => success -// 1 => error -uint8_t i2c_master_start(uint8_t address) { - TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); - - i2c_delay(); - - // check that we started successfully - if ( (TW_STATUS != TW_START) && (TW_STATUS != TW_REP_START)) - return 1; - - // send device address - TWDR = address; - TWCR = (1<<TWINT) | (1<<TWEN); - - i2c_delay(); - - if ( (TW_STATUS != TW_MT_SLA_ACK) && (TW_STATUS != TW_MR_SLA_ACK) ) - return 1; // slave did not acknowledge - else - return 0; // success -} - - -// Finish the i2c transaction. -void i2c_master_stop(void) { - TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); - - uint16_t lim = 0; - while(!(TWCR & (1<<TWSTO)) && lim < I2C_LOOP_TIMEOUT) - lim++; -} - -// Write one byte to the i2c slave. -// returns 0 => slave ACK -// 1 => slave NACK -uint8_t i2c_master_write(uint8_t data) { - TWDR = data; - TWCR = (1<<TWINT) | (1<<TWEN); - - i2c_delay(); - - // check if the slave acknowledged us - return (TW_STATUS == TW_MT_DATA_ACK) ? 0 : 1; -} - -// Read one byte from the i2c slave. If ack=1 the slave is acknowledged, -// if ack=0 the acknowledge bit is not set. -// returns: byte read from i2c device -uint8_t i2c_master_read(int ack) { - TWCR = (1<<TWINT) | (1<<TWEN) | (ack<<TWEA); - - i2c_delay(); - return TWDR; -} - -void i2c_reset_state(void) { - TWCR = 0; -} - -void i2c_slave_init(uint8_t address) { - TWAR = address << 0; // slave i2c address - // TWEN - twi enable - // TWEA - enable address acknowledgement - // TWINT - twi interrupt flag - // TWIE - enable the twi interrupt - TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN); -} - -ISR(TWI_vect); - -ISR(TWI_vect) { - uint8_t ack = 1; - switch(TW_STATUS) { - case TW_SR_SLA_ACK: - // this device has been addressed as a slave receiver - slave_has_register_set = false; - break; - - case TW_SR_DATA_ACK: - // this device has received data as a slave receiver - // The first byte that we receive in this transaction sets the location - // of the read/write location of the slaves memory that it exposes over - // i2c. After that, bytes will be written at slave_buffer_pos, incrementing - // slave_buffer_pos after each write. - if(!slave_has_register_set) { - slave_buffer_pos = TWDR; - // don't acknowledge the master if this memory loctaion is out of bounds - if ( slave_buffer_pos >= SLAVE_BUFFER_SIZE ) { - ack = 0; - slave_buffer_pos = 0; - } - slave_has_register_set = true; - } else { - i2c_slave_buffer[slave_buffer_pos] = TWDR; - BUFFER_POS_INC(); - } - break; - - case TW_ST_SLA_ACK: - case TW_ST_DATA_ACK: - // master has addressed this device as a slave transmitter and is - // requesting data. - TWDR = i2c_slave_buffer[slave_buffer_pos]; - BUFFER_POS_INC(); - break; - - case TW_BUS_ERROR: // something went wrong, reset twi state - TWCR = 0; - default: - break; - } - // Reset everything, so we are ready for the next TWI interrupt - TWCR |= (1<<TWIE) | (1<<TWINT) | (ack<<TWEA) | (1<<TWEN); -} - - - -#endif |