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 000000000..2773e0077
--- /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);
+}