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Diffstat (limited to 'libraries/Wire/Wire.cpp')
| -rw-r--r-- | libraries/Wire/Wire.cpp | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/libraries/Wire/Wire.cpp b/libraries/Wire/Wire.cpp new file mode 100644 index 0000000..d646132 --- /dev/null +++ b/libraries/Wire/Wire.cpp @@ -0,0 +1,182 @@ +/****************************************************************************** + * 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. + *****************************************************************************/ + +/** + * @file Wire.cpp + * @author Trystan Jones <crenn6977@gmail.com> + * @brief Wire library, uses the WireBase to create the primary interface + * while keeping low level interactions invisible to the user. + */ + +/* + * Library updated by crenn to follow new Wire system. + * Code was derived from the original Wire for maple code by leaflabs and the + * modifications by gke and ala42. + */ + +#include <Wire/Wire.h> + +#define I2C_WRITE 0 +#define I2C_READ 1 + +/* low level conventions: + * - SDA/SCL idle high (expected high) + * - always start with i2c_delay rather than end + */ + +void TwoWire::set_scl(bool state) { + I2C_DELAY(this->i2c_delay); + digitalWrite(this->scl_pin,state); + //Allow for clock stretching - dangerous currently + if (state == HIGH) { + while(digitalRead(this->scl_pin) == 0); + } +} + +void TwoWire::set_sda(bool state) { + I2C_DELAY(this->i2c_delay); + digitalWrite(this->sda_pin, state); +} + +void TwoWire::i2c_start() { + set_sda(LOW); + set_scl(LOW); +} + +void TwoWire::i2c_stop() { + set_sda(LOW); + set_scl(HIGH); + set_sda(HIGH); +} + +bool TwoWire::i2c_get_ack() { + set_scl(LOW); + set_sda(HIGH); + set_scl(HIGH); + + bool ret = !digitalRead(this->sda_pin); + set_scl(LOW); + return ret; +} + +void TwoWire::i2c_send_ack() { + set_sda(LOW); + set_scl(HIGH); + set_scl(LOW); +} + +void TwoWire::i2c_send_nack() { + set_sda(HIGH); + set_scl(HIGH); + set_scl(LOW); +} + +uint8 TwoWire::i2c_shift_in() { + uint8 data = 0; + set_sda(HIGH); + + int i; + for (i = 0; i < 8; i++) { + set_scl(HIGH); + data |= digitalRead(this->sda_pin) << (7-i); + set_scl(LOW); + } + + return data; +} + +void TwoWire::i2c_shift_out(uint8 val) { + int i; + for (i = 0; i < 8; i++) { + set_sda(!!(val & (1 << (7 - i)) ) ); + set_scl(HIGH); + set_scl(LOW); + } +} + +uint8 TwoWire::process() { + itc_msg.xferred = 0; + + uint8 sla_addr = (itc_msg.addr << 1); + if (itc_msg.flags == I2C_MSG_READ) { + sla_addr |= I2C_READ; + } + i2c_start(); + // shift out the address we're transmitting to + i2c_shift_out(sla_addr); + if (!i2c_get_ack()) { + return ENACKADDR; + } + // Recieving + if (itc_msg.flags == I2C_MSG_READ) { + while (itc_msg.xferred < itc_msg.length) { + itc_msg.data[itc_msg.xferred++] = i2c_shift_in(); + if (itc_msg.xferred < itc_msg.length) { + i2c_send_ack(); + } else { + i2c_send_nack(); + } + } + } + // Sending + else { + for (uint8 i = 0; i < itc_msg.length; i++) { + i2c_shift_out(itc_msg.data[i]); + if (!i2c_get_ack()) { + return ENACKTRNS; + } + itc_msg.xferred++; + } + } + i2c_stop(); + return SUCCESS; +} + +// TODO: Add in Error Handling if pins is out of range for other Maples +// TODO: Make delays more capable +TwoWire::TwoWire(uint8 scl, uint8 sda, uint8 delay) : i2c_delay(delay) { + this->scl_pin=scl; + this->sda_pin=sda; +} + +void TwoWire::begin(uint8 self_addr) { + tx_buf_idx = 0; + tx_buf_overflow = false; + rx_buf_idx = 0; + rx_buf_len = 0; + pinMode(this->scl_pin, OUTPUT_OPEN_DRAIN); + pinMode(this->sda_pin, OUTPUT_OPEN_DRAIN); + set_scl(HIGH); + set_sda(HIGH); +} + +TwoWire::~TwoWire() { + this->scl_pin=0; + this->sda_pin=0; +} + +// Declare the instance that the users of the library can use +TwoWire Wire(SCL, SDA, SOFT_STANDARD); |