diff options
Diffstat (limited to 'platforms/avr/drivers/i2c_master.c')
| -rw-r--r-- | platforms/avr/drivers/i2c_master.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/platforms/avr/drivers/i2c_master.c b/platforms/avr/drivers/i2c_master.c new file mode 100644 index 0000000000..2773e00778 --- /dev/null +++ b/platforms/avr/drivers/i2c_master.c @@ -0,0 +1,241 @@ +/* Copyright (C) 2019 Elia Ritterbusch + + + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +/* Library made by: g4lvanix + * GitHub repository: https://github.com/g4lvanix/I2C-master-lib + */ + +#include <avr/io.h> +#include <util/twi.h> + +#include "i2c_master.h" +#include "timer.h" +#include "wait.h" + +#ifndef F_SCL +# define F_SCL 400000UL // SCL frequency +#endif + +#ifndef I2C_START_RETRY_COUNT +# define I2C_START_RETRY_COUNT 20 +#endif // I2C_START_RETRY_COUNT + +#define TWBR_val (((F_CPU / F_SCL) - 16) / 2) + +#define MAX(X, Y) ((X) > (Y) ? (X) : (Y)) + +void i2c_init(void) { + TWSR = 0; /* no prescaler */ + TWBR = (uint8_t)TWBR_val; + +#ifdef __AVR_ATmega32A__ + // set pull-up resistors on I2C bus pins + PORTC |= 0b11; + + // enable TWI (two-wire interface) + TWCR |= (1 << TWEN); + + // enable TWI interrupt and slave address ACK + TWCR |= (1 << TWIE); + TWCR |= (1 << TWEA); +#endif +} + +static i2c_status_t i2c_start_impl(uint8_t address, uint16_t timeout) { + // reset TWI control register + TWCR = 0; + // transmit START condition + TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN); + + uint16_t timeout_timer = timer_read(); + while (!(TWCR & (1 << TWINT))) { + if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) { + return I2C_STATUS_TIMEOUT; + } + } + + // check if the start condition was successfully transmitted + if (((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)) { + return I2C_STATUS_ERROR; + } + + // load slave address into data register + TWDR = address; + // start transmission of address + TWCR = (1 << TWINT) | (1 << TWEN); + + timeout_timer = timer_read(); + while (!(TWCR & (1 << TWINT))) { + if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) { + return I2C_STATUS_TIMEOUT; + } + } + + // check if the device has acknowledged the READ / WRITE mode + uint8_t twst = TW_STATUS & 0xF8; + if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) { + return I2C_STATUS_ERROR; + } + + return I2C_STATUS_SUCCESS; +} + +i2c_status_t i2c_start(uint8_t address, uint16_t timeout) { + // Retry i2c_start_impl a bunch times in case the remote side has interrupts disabled. + uint16_t timeout_timer = timer_read(); + uint16_t time_slice = MAX(1, (timeout == (I2C_TIMEOUT_INFINITE)) ? 5 : (timeout / (I2C_START_RETRY_COUNT))); // if it's infinite, wait 1ms between attempts, otherwise split up the entire timeout into the number of retries + i2c_status_t status; + do { + status = i2c_start_impl(address, time_slice); + } while ((status < 0) && ((timeout == I2C_TIMEOUT_INFINITE) || (timer_elapsed(timeout_timer) < timeout))); + return status; +} + +i2c_status_t i2c_write(uint8_t data, uint16_t timeout) { + // load data into data register + TWDR = data; + // start transmission of data + TWCR = (1 << TWINT) | (1 << TWEN); + + uint16_t timeout_timer = timer_read(); + while (!(TWCR & (1 << TWINT))) { + if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) { + return I2C_STATUS_TIMEOUT; + } + } + + if ((TW_STATUS & 0xF8) != TW_MT_DATA_ACK) { + return I2C_STATUS_ERROR; + } + + return I2C_STATUS_SUCCESS; +} + +int16_t i2c_read_ack(uint16_t timeout) { + // start TWI module and acknowledge data after reception + TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA); + + uint16_t timeout_timer = timer_read(); + while (!(TWCR & (1 << TWINT))) { + if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) { + return I2C_STATUS_TIMEOUT; + } + } + + // return received data from TWDR + return TWDR; +} + +int16_t i2c_read_nack(uint16_t timeout) { + // start receiving without acknowledging reception + TWCR = (1 << TWINT) | (1 << TWEN); + + uint16_t timeout_timer = timer_read(); + while (!(TWCR & (1 << TWINT))) { + if ((timeout != I2C_TIMEOUT_INFINITE) && ((timer_read() - timeout_timer) >= timeout)) { + return I2C_STATUS_TIMEOUT; + } + } + + // return received data from TWDR + return TWDR; +} + +i2c_status_t i2c_transmit(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout) { + i2c_status_t status = i2c_start(address | I2C_WRITE, timeout); + + for (uint16_t i = 0; i < length && status >= 0; i++) { + status = i2c_write(data[i], timeout); + } + + i2c_stop(); + + return status; +} + +i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout) { + i2c_status_t status = i2c_start(address | I2C_READ, timeout); + + for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) { + status = i2c_read_ack(timeout); + if (status >= 0) { + data[i] = status; + } + } + + if (status >= 0) { + status = i2c_read_nack(timeout); + if (status >= 0) { + data[(length - 1)] = status; + } + } + + i2c_stop(); + + return (status < 0) ? status : I2C_STATUS_SUCCESS; +} + +i2c_status_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout) { + i2c_status_t status = i2c_start(devaddr | 0x00, timeout); + if (status >= 0) { + status = i2c_write(regaddr, timeout); + + for (uint16_t i = 0; i < length && status >= 0; i++) { + status = i2c_write(data[i], timeout); + } + } + + i2c_stop(); + + return status; +} + +i2c_status_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout) { + i2c_status_t status = i2c_start(devaddr, timeout); + if (status < 0) { + goto error; + } + + status = i2c_write(regaddr, timeout); + if (status < 0) { + goto error; + } + + status = i2c_start(devaddr | 0x01, timeout); + + for (uint16_t i = 0; i < (length - 1) && status >= 0; i++) { + status = i2c_read_ack(timeout); + if (status >= 0) { + data[i] = status; + } + } + + if (status >= 0) { + status = i2c_read_nack(timeout); + if (status >= 0) { + data[(length - 1)] = status; + } + } + +error: + i2c_stop(); + + return (status < 0) ? status : I2C_STATUS_SUCCESS; +} + +void i2c_stop(void) { + // transmit STOP condition + TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO); +} |