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Diffstat (limited to 'libraries/Wire/Wire.cpp')
| -rw-r--r-- | libraries/Wire/Wire.cpp | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/libraries/Wire/Wire.cpp b/libraries/Wire/Wire.cpp new file mode 100644 index 0000000..736bd25 --- /dev/null +++ b/libraries/Wire/Wire.cpp @@ -0,0 +1,259 @@ +/****************************************************************************** + * The MIT License + * + * Copyright (c) 2010 LeafLabs LLC. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + *****************************************************************************/ + +/** + * @brief Wire library, ported from Arduino. Provides a simplistic + * interface to i2c. + */ + +#include "Wire.h" +#include "wirish.h" + +/* low level conventions: + * - SDA/SCL idle high (expected high) + * - always start with i2c_delay rather than end + */ +uint32 i2c_delay = 1; + +void i2c_start(Port port) { + I2C_DELAY; + digitalWrite(port.sda,LOW); + I2C_DELAY; + digitalWrite(port.scl,LOW); +} + +void i2c_stop(Port port) { + I2C_DELAY; + digitalWrite(port.scl,HIGH); + I2C_DELAY; + digitalWrite(port.sda,HIGH); +} + +boolean i2c_get_ack(Port port) { + I2C_DELAY; + digitalWrite(port.scl,LOW); + I2C_DELAY; + digitalWrite(port.sda,HIGH); + I2C_DELAY; + digitalWrite(port.scl,HIGH); + I2C_DELAY; + + if (!digitalRead(port.sda)) { + I2C_DELAY; + digitalWrite(port.scl,LOW); + return true; + } else { + I2C_DELAY; + digitalWrite(port.scl,LOW); + return false; + } +} + +void i2c_send_ack(Port port) { + I2C_DELAY; + digitalWrite(port.sda,LOW); + I2C_DELAY; + digitalWrite(port.scl,HIGH); + I2C_DELAY; + digitalWrite(port.scl,LOW); +} + +void i2c_send_nack(Port port) { + I2C_DELAY; + digitalWrite(port.sda,HIGH); + I2C_DELAY; + digitalWrite(port.scl,HIGH); +} + +uint8 i2c_shift_in(Port port) { + uint8 data = 0; + + int i; + for (i=0;i<8;i++) { + I2C_DELAY; + digitalWrite(port.scl,HIGH); + I2C_DELAY; + data += digitalRead(port.sda) << (7-i); + I2C_DELAY; + digitalWrite(port.scl,LOW); + } + + return data; +} + +void i2c_shift_out(Port port, uint8 val) { + int i; + for (i=0;i<8;i++) { + I2C_DELAY; + digitalWrite(port.sda, !!(val & (1 << (7 - i)))); + I2C_DELAY; + digitalWrite(port.scl, HIGH); + I2C_DELAY; + digitalWrite(port.scl, LOW); + } +} + +TwoWire::TwoWire() { + i2c_delay = 0; + rx_buf_idx = 0; + rx_buf_len = 0; + tx_addr = 0; + tx_buf_idx = 0; + tx_buf_overflow = false; +} + +/* + * Sets pins SDA and SCL to OUPTUT_OPEN_DRAIN, joining I2C bus as + * master. If you want them to be some other pins, use begin(uint8, + * uint8); + */ +void TwoWire::begin() { + begin(SDA, SCL); +} + +/* + * Joins I2C bus as master on given SDA and SCL pins. + */ +void TwoWire::begin(uint8 sda, uint8 scl) { + port.sda = sda; + port.scl = scl; + pinMode(scl, OUTPUT_OPEN_DRAIN); + pinMode(sda, OUTPUT_OPEN_DRAIN); + digitalWrite(scl, HIGH); + digitalWrite(sda, HIGH); +} + +void TwoWire::beginTransmission(uint8 slave_address) { + tx_addr = slave_address; + tx_buf_idx = 0; + tx_buf_overflow = false; + rx_buf_idx = 0; + rx_buf_len = 0; +} + +void TwoWire::beginTransmission(int slave_address) { + beginTransmission((uint8)slave_address); +} + +uint8 TwoWire::endTransmission(void) { + if (tx_buf_overflow) return EDATA; + + i2c_start(port); + + i2c_shift_out(port, (tx_addr << 1) | I2C_WRITE); + if (!i2c_get_ack(port)) return ENACKADDR; + + // shift out the address we're transmitting to + for (uint8 i = 0; i < tx_buf_idx; i++) { + uint8 ret = writeOneByte(tx_buf[i]); + if (ret) return ret; // SUCCESS is 0 + } + + i2c_stop(port); + + tx_buf_idx = 0; + tx_buf_overflow = false; + return SUCCESS; +} + +uint8 TwoWire::requestFrom(uint8 address, int num_bytes) { + if (num_bytes > WIRE_BUFSIZ) num_bytes = WIRE_BUFSIZ; + + rx_buf_idx = 0; + rx_buf_len = 0; + while (rx_buf_len < num_bytes) { + if(!readOneByte(address, rx_buf + rx_buf_len)) rx_buf_len++; + else break; + } + return rx_buf_len; +} + +uint8 TwoWire::requestFrom(int address, int numBytes) { + return TwoWire::requestFrom((uint8)address, (uint8) numBytes); +} + +void TwoWire::send(uint8 value) { + if (tx_buf_idx == WIRE_BUFSIZ) { + tx_buf_overflow = true; + return; + } + + tx_buf[tx_buf_idx++] = value; +} + +void TwoWire::send(uint8* buf, int len) { + for (uint8 i = 0; i < len; i++) send(buf[i]); +} + +void TwoWire::send(int value) { + send((uint8)value); +} + +void TwoWire::send(int* buf, int len) { + send((uint8*)buf, (uint8)len); +} + +void TwoWire::send(char* buf) { + uint8 *ptr = (uint8*)buf; + while(*ptr) { + send(*ptr); + ptr++; + } +} + +uint8 TwoWire::available() { + return rx_buf_len - rx_buf_idx; +} + +uint8 TwoWire::receive() { + if (rx_buf_idx == rx_buf_len) return 0; + return rx_buf[rx_buf_idx++]; +} + +// private methods + +uint8 TwoWire::writeOneByte(uint8 byte) { + i2c_shift_out(port, byte); + if (!i2c_get_ack(port)) return ENACKTRNS; + + return SUCCESS; +} + +uint8 TwoWire::readOneByte(uint8 address, uint8 *byte) { + i2c_start(port); + + i2c_shift_out(port, (address << 1) | I2C_READ); + if (!i2c_get_ack(port)) return ENACKADDR; + + *byte = i2c_shift_in(port); + + i2c_send_nack(port); + i2c_stop(port); + + return SUCCESS; // no real way of knowing, but be optimistic! +} + +// Declare the instance that the users of the library can use +TwoWire Wire; + |