diff options
Diffstat (limited to 'drivers/avr/i2c_master.c')
| -rw-r--r--[-rwxr-xr-x] | drivers/avr/i2c_master.c | 254 |
1 files changed, 133 insertions, 121 deletions
diff --git a/drivers/avr/i2c_master.c b/drivers/avr/i2c_master.c index f4a7e6bf52..52924437e0 100755..100644 --- a/drivers/avr/i2c_master.c +++ b/drivers/avr/i2c_master.c @@ -25,188 +25,200 @@ #include "wait.h" #ifndef F_SCL -# define F_SCL 400000UL // SCL frequency +# define F_SCL 400000UL // SCL frequency #endif #define Prescaler 1 #define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16) / 2) void i2c_init(void) { - TWSR = 0; /* no prescaler */ - TWBR = (uint8_t)TWBR_val; + 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 } i2c_status_t i2c_start(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; + // 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_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; + // 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; - } + if ((TW_STATUS & 0xF8) != TW_MT_DATA_ACK) { + return I2C_STATUS_ERROR; + } - return I2C_STATUS_SUCCESS; + 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; + // 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; + // 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; + // 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; + // 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); + 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); - } + for (uint16_t i = 0; i < length && status >= 0; i++) { + status = i2c_write(data[i], timeout); + } - i2c_stop(); + i2c_stop(); - return status; + 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); + 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; + 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; + status = i2c_read_nack(timeout); + if (status >= 0) { + data[(length - 1)] = status; + } } - } - i2c_stop(); + i2c_stop(); - return (status < 0) ? status : I2C_STATUS_SUCCESS; + 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); + 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); + for (uint16_t i = 0; i < length && status >= 0; i++) { + status = i2c_write(data[i], timeout); + } } - } - i2c_stop(); + i2c_stop(); - return status; + 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; - } + 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_write(regaddr, timeout); + if (status < 0) { + goto error; + } - status = i2c_start(devaddr | 0x01, timeout); + 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; + 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; + status = i2c_read_nack(timeout); + if (status >= 0) { + data[(length - 1)] = status; + } } - } error: - i2c_stop(); + i2c_stop(); - return (status < 0) ? status : I2C_STATUS_SUCCESS; + return (status < 0) ? status : I2C_STATUS_SUCCESS; } void i2c_stop(void) { - // transmit STOP condition - TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO); + // transmit STOP condition + TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO); } |