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https://github.com/eddyem/STM8_samples.git
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Added software I2C on timer TIM2
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eddyem
238
si7005_softi2c/soft_i2c.c
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238
si7005_softi2c/soft_i2c.c
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/*
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* soft_i2c.c - functions to work with SW I2C
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*
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* Copyright 2015 Edward V. Emelianoff <eddy@sao.ru, edward.emelianoff@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include "soft_i2c.h"
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#include "ports_definition.h"
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/*
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* In file ports_definition.h should be defined:
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* I2C_SDA_PIN, I2C_SDA_PORT, I2C_SCL_PIN and I2C_SCL_PORT
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*/
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static U8 addr7r = 0, addr7w = 0;
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extern volatile unsigned long Global_time;
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#define PAUSE(val) do{TIM2_ARRH = 0; TIM2_ARRL = val; TIM2_CR1 |= TIM_CR1_CEN; \
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while(!TIM2_SR1 & TIM_SR1_UIF); TIM2_SR1 = 0;}while(0)
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#define H_DEL PAUSE(30)
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#define Q_DEL PAUSE(15)
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#define H_SCL PORT(I2C_SCL_PORT, ODR) |= I2C_SCL_PIN
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#define L_SCL PORT(I2C_SCL_PORT, ODR) &= ~I2C_SCL_PIN
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#define H_SDA PORT(I2C_SDA_PORT, ODR) |= I2C_SDA_PIN
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#define L_SDA PORT(I2C_SDA_PORT, ODR) &= ~I2C_SDA_PIN
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#define CHK_SDA (PORT(I2C_SDA_PORT, IDR) & I2C_SDA_PIN)
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#define CHK_SCL (PORT(I2C_SCL_PORT, IDR) & I2C_SCL_PIN)
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/**
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* configure timer for 100kHz speed in standard mode
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*/
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void i2c_setup(){
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// configure pins: I2C_SDA; I2C_SCL (both opendrain)
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PORT(I2C_SDA_PORT, ODR) |= I2C_SDA_PIN; // set to 1
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PORT(I2C_SCL_PORT, ODR) |= I2C_SCL_PIN;
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PORT(I2C_SDA_PORT, DDR) |= I2C_SDA_PIN;
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PORT(I2C_SCL_PORT, DDR) |= I2C_SCL_PIN;
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PORT(I2C_SDA_PORT, CR2) |= I2C_SDA_PIN;
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PORT(I2C_SCL_PORT, CR2) |= I2C_SCL_PIN;
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// configure TIM2 for delays
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TIM2_PSCR = 0; // 16MHz (for working @ 100kHz: 1us \approx 16tacts)
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TIM2_CR1 = TIM_CR1_OPM; // one-pulse mode
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}
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void i2c_set_addr7(U8 addr){
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addr7w = addr << 1;
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addr7r = addr7w | 1;
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}
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void SoftStart(){
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H_SCL;
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H_DEL;
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L_SDA;
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H_DEL;
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L_SCL;
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H_DEL;
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}
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void SoftStop(){
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L_SDA;
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L_SCL;
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H_DEL;
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H_SCL;
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H_DEL;
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H_SDA;
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}
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/**
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* send 1 byte without start/stop
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*/
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U8 softi2c_send(U8 data){
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U8 i;
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for(i=0; i < 8; i++){
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L_SCL;
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if(data & 0x80)
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H_SDA;
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else
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L_SDA;
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H_DEL;
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H_SCL;
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H_DEL;
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data <<= 1;
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}
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// ACK
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L_SCL;
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H_SDA;
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H_DEL;
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H_SCL;
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Q_DEL;
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i = !(CHK_SDA);
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// Q_DEL;
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L_SCL;
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// Q_DEL;
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return i;
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}
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/**
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* receive one byte without start/stop
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*/
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U8 softi2c_receive(U8 ack){
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U8 data = 0, i;
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for(i=0; i<8; i++){
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data <<= 1;
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L_SCL;
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H_DEL;
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H_SCL;
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if(CHK_SDA) data |= 1;
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H_DEL;
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}
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// prepare for ACK/NACK
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L_SCL;
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if(ack) L_SDA;
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else H_SDA;
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H_DEL;
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H_SCL;
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H_DEL;
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L_SCL;
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H_SDA;
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return data;
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}
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/**
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* send one byte in 7bit address mode
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* @param data - data to write
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* @param stop - ==1 to send stop event
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* @return I2C_OK if success errcode if fails
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*/
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i2c_status i2c_7bit_send_onebyte(U8 data, U8 stop){
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i2c_status ret = I2C_LINEBUSY;
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U8 err = 1;
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H_SCL; H_SDA;
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if(!CHK_SDA || !CHK_SCL) goto eotr;
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SoftStart();
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ret = I2C_NACK;
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if(!softi2c_send(addr7w)) goto eotr;
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if(softi2c_send(data)){
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ret = I2C_OK;
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err = 0;
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}
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eotr:
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if(stop || err){
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SoftStop();
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}
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return ret;
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}
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/**
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* send datalen bytes over I2C
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* @param data - data to write
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* @param datalen - amount of bytes in data array
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* @param stop - ==1 to send stop event
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* return I2C_OK if OK
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*/
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i2c_status i2c_7bit_send(U8 *data, U8 datalen, U8 stop){
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i2c_status ret = I2C_LINEBUSY;
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U8 err = 1;
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H_SCL; H_SDA;
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if(!CHK_SDA || !CHK_SCL) goto eotr;
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SoftStart();
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ret = I2C_NACK;
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if(!softi2c_send(addr7w)) goto eotr;
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while(datalen--){
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if(!softi2c_send(*data++)) goto eotr;
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}
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ret = I2C_OK;
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err = 0;
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eotr:
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if(stop || err){
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SoftStop();
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}
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return I2C_OK;
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}
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/**
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* get one byte by I2C
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* @param data - data to read (one byte)
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* @param wait - leaved for compatibility with HW I2C
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* @return I2C_OK if ok || error code
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*/
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i2c_status i2c_7bit_receive_onebyte(U8 *data, U8 wait){
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i2c_status ret = I2C_NACK;
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H_SCL; H_SDA;
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(void) wait;
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if(!CHK_SDA || !CHK_SCL){
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ret = I2C_LINEBUSY;
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goto eotr;
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}
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SoftStart();
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if(!softi2c_send(addr7r)) goto eotr;
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*data = softi2c_receive(0);
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ret = I2C_OK;
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eotr:
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SoftStop();
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return ret;
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}
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/**
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* receive 2 bytes by I2C
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* @param data - data to read (two bytes array, 0 first)
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* @param wait - ==1 to wait while LINEBUSY (can send STOP before reading)
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* @return I2C_OK if ok || error code
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*/
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i2c_status i2c_7bit_receive_twobyte(U8 *data, U8 wait){
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i2c_status ret = I2C_NACK;
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H_SCL; H_SDA;
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(void) wait;
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if(!CHK_SDA || !CHK_SCL){
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ret = I2C_LINEBUSY;
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goto eotr;
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}
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SoftStart();
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if(!softi2c_send(addr7r)) goto eotr;
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data[0] = softi2c_receive(1);
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data[1] = softi2c_receive(0);
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ret = I2C_OK;
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eotr:
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SoftStop();
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return ret;
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}
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INTERRUPT_HANDLER(I2C_IRQHandler, 19){
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}
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