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/******************************************************************************
* 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()) {
i2c_stop(); // Fix up the state of the bus
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()) {
i2c_stop(); // Fix up the state of the bus
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);
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