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SoftwareI2C.cpp
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SoftwareI2C.cpp
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/*
SoftwareI2C.cpp
2012 Copyright (c) Seeed Technology Inc. All right reserved.
Author:Loovee
Author:Loovee
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <Arduino.h>
#include "SoftwareI2C.h"
/*************************************************************************************************
* Function Name: begin
* Description: config IO
* Parameters: Sda: Scl:
* Return: none
*************************************************************************************************/
void SoftwareI2C::begin(int Sda, int Scl)
{
pinSda = Sda;
pinScl = Scl;
pinMode(pinScl, OUTPUT);
pinMode(pinSda, OUTPUT);
sda_in_out = OUTPUT;
digitalWrite(pinScl, HIGH);
digitalWrite(pinSda, HIGH);
}
/*************************************************************************************************
* Function Name: sdaSet
* Description: set sda
* Parameters: ucDta: HIGH or LOW
* Return: none
*************************************************************************************************/
void SoftwareI2C::sdaSet(uchar ucDta)
{
if(sda_in_out != OUTPUT)
{
sda_in_out = OUTPUT;
pinMode(pinSda, OUTPUT);
}
digitalWrite(pinSda, ucDta);
}
/*************************************************************************************************
* Function Name: sclSet
* Description: set scl
* Parameters: ucDta: HIGH or LOW
* Return: none
*************************************************************************************************/
void SoftwareI2C::sclSet(uchar ucDta)
{
digitalWrite(pinScl, ucDta);
}
/*************************************************************************************************
* Function Name: getAck
* Description: get ack
* Parameters: None
* Return: 0 – Nak; 1 – Ack
*************************************************************************************************/
uchar SoftwareI2C::getAck(void)
{
sclSet(LOW);
pinMode(pinSda, INPUT);
sda_in_out = INPUT;
sclSet(HIGH);
unsigned long timer_t = micros();
while(1)
{
if(!digitalRead(pinSda)) // get ack
{
return GETACK;
}
if(micros() - timer_t > 100)return GETNAK;
}
}
/*************************************************************************************************
* Function Name: sendStart
* Description: send start clock
* Parameters: None
* Return: None
*************************************************************************************************/
void SoftwareI2C::sendStart(void)
{
sdaSet(LOW);
}
/*************************************************************************************************
* Function Name: setClockDivider
* Description: setup clock divider for spi bus
* Parameters: divider – clock divider
* Return: 0 – setup ok; 1 – setup failed
*************************************************************************************************/
void SoftwareI2C::sendStop(void)
{
sclSet(LOW);
sdaSet(LOW);
sclSet(HIGH);
sdaSet(HIGH);
}
/*************************************************************************************************
* Function Name: sendByte
* Description: send a byte
* Parameters: ucDta: data to send
* Return: None
*************************************************************************************************/
void SoftwareI2C::sendByte(uchar ucDta)
{
for(int i=0; i<8; i++)
{
sclSet(LOW);
sdaSet((ucDta&0x80)!=0);
ucDta <<= 0;
sclSet(HIGH);
sdaSet((ucDta&0x80)!=0);
ucDta <<= 1;
}
}
/*************************************************************************************************
* Function Name: sendByteAck
* Description: send a byte and get ack signal
* Parameters: ucDta: data to send
* Return: 0: get nak 1: get ack
*************************************************************************************************/
uchar SoftwareI2C::sendByteAck(uchar ucDta)
{
sendByte(ucDta);
return getAck();
}
/*************************************************************************************************
* Function Name: beginTransmission
* Description: send begin signal
* Parameters: divider – clock divider
* Return: 0: get nak 1: get ack
*************************************************************************************************/
uchar SoftwareI2C::beginTransmission(uchar addr)
{
sendStart(); // start signal
uchar ret = sendByteAck(addr<<1); // send write address and get ack
//sclSet(LOW);
return ret;
}
/*************************************************************************************************
* Function Name: endTransmission
* Description: send stop signal
* Parameters: None
* Return: None
*************************************************************************************************/
uchar SoftwareI2C::endTransmission()
{
sendStop();
return 0;
}
/*************************************************************************************************
* Function Name: write
* Description: send a byte
* Parameters: dta: data to send
* Return: 0: get nak 1: get ack
*************************************************************************************************/
uchar SoftwareI2C::write(uchar dta)
{
return sendByteAck(dta);
}
/*************************************************************************************************
* Function Name: write
* Description: write array
* Parameters: len - length of the array
*dta - array to be sent
* Return: 0: get nak 1: get ack
*************************************************************************************************/
uchar SoftwareI2C::write(uchar len, uchar *dta)
{
for(int i=0; i<len; i++)
{
if(GETACK != write(dta[i]))
{
return GETNAK;
}
}
return GETACK;
}
/*************************************************************************************************
* Function Name: requestFrom
* Description: request data from slave
* Parameters: addr - address of slave
len - length of request
* Return: 0: get nak 1: get ack
*************************************************************************************************/
uchar SoftwareI2C::requestFrom(uchar addr, uchar len)
{
sendStart(); // start signal
recv_len = len;
uchar ret = sendByteAck((addr<<1)+1); // send write address and get ack
//sclSet(LOW);
return ret;
}
/*************************************************************************************************
* Function Name: read
* Description: read a byte from i2c
* Parameters: None
* Return: data get
*************************************************************************************************/
uchar SoftwareI2C::read()
{
if(!recv_len)return 0;
uchar ucRt = 0;
pinMode(pinSda, INPUT);
sda_in_out = INPUT;
for(int i=0; i<8; i++)
{
unsigned char ucBit;
sclSet(LOW);
sclSet(HIGH);
ucBit = digitalRead(pinSda);
ucRt = (ucRt << 1) + ucBit;
}
uchar dta = ucRt;
recv_len--;
if(recv_len>0) // send ACK
{
sclSet(LOW); // sclSet(HIGH)
sdaSet(LOW); // sdaSet(LOW)
sclSet(HIGH); // sclSet(LOW)
sclSet(LOW);
}
else // send NAK
{
sclSet(LOW); // sclSet(HIGH)
sdaSet(HIGH); // sdaSet(LOW)
sclSet(HIGH); // sclSet(LOW)
sclSet(LOW);
sendStop();
}
return dta;
}
/*********************************************************************************************************
END FILE
*********************************************************************************************************/