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esp8266/cores/esp8266/core_esp8266_si2c.c
Matej Sychra aa22c07312 clock stretch fix done right (#5363)
2018-11-22 14:21:21 -02:00

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/*
si2c.c - Software I2C library for esp8266
Copyright (c) 2015 Hristo Gochkov. All rights reserved.
This file is part of the esp8266 core for Arduino environment.
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
Modified January 2017 by Bjorn Hammarberg (bjoham@esp8266.com) - i2c slave support
*/
#include "twi.h"
#include "pins_arduino.h"
#include "wiring_private.h"
unsigned int preferred_si2c_clock = 100000;
#include "twi_util.h"
#include "ets_sys.h"
unsigned char twi_dcount = 18;
static unsigned char twi_sda, twi_scl;
static uint32_t twi_clockStretchLimit;
static unsigned char twi_addr = 0;
// modes (private)
#define TWIPM_UNKNOWN 0
#define TWIPM_IDLE 1
#define TWIPM_ADDRESSED 2
#define TWIPM_WAIT 3
// states (private)
#define TWIP_UNKNOWN 0
#define TWIP_IDLE 1
#define TWIP_START 2
#define TWIP_SEND_ACK 3
#define TWIP_WAIT_ACK 4
#define TWIP_WAIT_STOP 5
#define TWIP_SLA_W 6
#define TWIP_SLA_R 7
#define TWIP_REP_START 8
#define TWIP_READ 9
#define TWIP_STOP 10
#define TWIP_REC_ACK 11
#define TWIP_READ_ACK 12
#define TWIP_RWAIT_ACK 13
#define TWIP_WRITE 14
#define TWIP_BUS_ERR 15
static volatile uint8_t twip_mode = TWIPM_IDLE;
static volatile uint8_t twip_state = TWIP_IDLE;
static volatile uint8_t twip_status = TW_NO_INFO;
static volatile uint8_t bitCount = 0;
#define TWDR twi_data
static volatile uint8_t twi_data = 0x00;
static volatile uint8_t twi_ack = 0;
static volatile uint8_t twi_ack_rec = 0;
static volatile int twi_timeout_ms = 10;
#define TWI_READY 0
#define TWI_MRX 1
#define TWI_MTX 2
#define TWI_SRX 3
#define TWI_STX 4
static volatile uint8_t twi_state = TWI_READY;
static volatile uint8_t twi_error = 0xFF;
static uint8_t twi_txBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_txBufferIndex;
static volatile uint8_t twi_txBufferLength;
static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_rxBufferIndex;
static void (*twi_onSlaveTransmit)(void);
static void (*twi_onSlaveReceive)(uint8_t*, size_t);
static void onSclChange(void);
static void onSdaChange(void);
#define EVENTTASK_QUEUE_SIZE 1
#define EVENTTASK_QUEUE_PRIO 2
#define TWI_SIG_RANGE 0x00000100
#define TWI_SIG_RX (TWI_SIG_RANGE + 0x01)
#define TWI_SIG_TX (TWI_SIG_RANGE + 0x02)
static ETSEvent eventTaskQueue[EVENTTASK_QUEUE_SIZE];
static void eventTask(ETSEvent *e);
static ETSTimer timer;
static void onTimer();
#define SDA_LOW() (GPES = (1 << twi_sda)) //Enable SDA (becomes output and since GPO is 0 for the pin, it will pull the line low)
#define SDA_HIGH() (GPEC = (1 << twi_sda)) //Disable SDA (becomes input and since it has pullup it will go high)
#define SDA_READ() ((GPI & (1 << twi_sda)) != 0)
#define SCL_LOW() (GPES = (1 << twi_scl))
#define SCL_HIGH() (GPEC = (1 << twi_scl))
#define SCL_READ() ((GPI & (1 << twi_scl)) != 0)
#ifndef FCPU80
#define FCPU80 80000000L
#endif
#if F_CPU == FCPU80
#define TWI_CLOCK_STRETCH_MULTIPLIER 3
#else
#define TWI_CLOCK_STRETCH_MULTIPLIER 6
#endif
void twi_setClock(unsigned int freq){
preferred_si2c_clock = freq;
#if F_CPU == FCPU80
if(freq <= 50000) twi_dcount = 38;//about 50KHz
else if(freq <= 100000) twi_dcount = 19;//about 100KHz
else if(freq <= 200000) twi_dcount = 8;//about 200KHz
else if(freq <= 300000) twi_dcount = 3;//about 300KHz
else if(freq <= 400000) twi_dcount = 1;//about 400KHz
else twi_dcount = 1;//about 400KHz
#else
if(freq <= 50000) twi_dcount = 64;//about 50KHz
else if(freq <= 100000) twi_dcount = 32;//about 100KHz
else if(freq <= 200000) twi_dcount = 14;//about 200KHz
else if(freq <= 300000) twi_dcount = 8;//about 300KHz
else if(freq <= 400000) twi_dcount = 5;//about 400KHz
else if(freq <= 500000) twi_dcount = 3;//about 500KHz
else if(freq <= 600000) twi_dcount = 2;//about 600KHz
else twi_dcount = 1;//about 700KHz
#endif
}
void twi_setClockStretchLimit(uint32_t limit){
twi_clockStretchLimit = limit * TWI_CLOCK_STRETCH_MULTIPLIER;
}
void twi_init(unsigned char sda, unsigned char scl)
{
// set timer function
ets_timer_setfn(&timer, onTimer, NULL);
// create event task
ets_task(eventTask, EVENTTASK_QUEUE_PRIO, eventTaskQueue, EVENTTASK_QUEUE_SIZE);
twi_sda = sda;
twi_scl = scl;
pinMode(twi_sda, INPUT_PULLUP);
pinMode(twi_scl, INPUT_PULLUP);
twi_setClock(preferred_si2c_clock);
twi_setClockStretchLimit(230); // default value is 230 uS
if (twi_addr != 0)
{
attachInterrupt(scl, onSclChange, CHANGE);
attachInterrupt(sda, onSdaChange, CHANGE);
}
}
void twi_setAddress(uint8_t address)
{
// set twi slave address (skip over R/W bit)
twi_addr = address << 1;
}
static void ICACHE_RAM_ATTR twi_delay(unsigned char v){
unsigned int i;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
unsigned int reg;
for (i = 0; i < v; i++) {
reg = GPI;
}
#pragma GCC diagnostic pop
}
static bool twi_write_start(void) {
SCL_HIGH();
SDA_HIGH();
if (SDA_READ() == 0) {
return false;
}
twi_delay(twi_dcount);
SDA_LOW();
twi_delay(twi_dcount);
return true;
}
static bool twi_write_stop(void){
uint32_t i = 0;
SCL_LOW();
SDA_LOW();
twi_delay(twi_dcount);
SCL_HIGH();
while (SCL_READ() == 0 && (i++) < twi_clockStretchLimit); // Clock stretching
twi_delay(twi_dcount);
SDA_HIGH();
twi_delay(twi_dcount);
return true;
}
static bool twi_write_bit(bool bit) {
uint32_t i = 0;
SCL_LOW();
if (bit) SDA_HIGH();
else SDA_LOW();
twi_delay(twi_dcount+1);
SCL_HIGH();
while (SCL_READ() == 0 && (i++) < twi_clockStretchLimit);// Clock stretching
twi_delay(twi_dcount);
return true;
}
static bool twi_read_bit(void) {
uint32_t i = 0;
SCL_LOW();
SDA_HIGH();
twi_delay(twi_dcount+2);
SCL_HIGH();
while (SCL_READ() == 0 && (i++) < twi_clockStretchLimit);// Clock stretching
bool bit = SDA_READ();
twi_delay(twi_dcount);
return bit;
}
static bool twi_write_byte(unsigned char byte) {
unsigned char bit;
for (bit = 0; bit < 8; bit++) {
twi_write_bit(byte & 0x80);
byte <<= 1;
}
return !twi_read_bit();//NACK/ACK
}
static unsigned char twi_read_byte(bool nack) {
unsigned char byte = 0;
unsigned char bit;
for (bit = 0; bit < 8; bit++) byte = (byte << 1) | twi_read_bit();
twi_write_bit(nack);
return byte;
}
unsigned char twi_writeTo(unsigned char address, unsigned char * buf, unsigned int len, unsigned char sendStop){
unsigned int i;
if(!twi_write_start()) return 4;//line busy
if(!twi_write_byte(((address << 1) | 0) & 0xFF)) {
if (sendStop) twi_write_stop();
return 2; //received NACK on transmit of address
}
for(i=0; i<len; i++) {
if(!twi_write_byte(buf[i])) {
if (sendStop) twi_write_stop();
return 3;//received NACK on transmit of data
}
}
if(sendStop) twi_write_stop();
i = 0;
while(SDA_READ() == 0 && (i++) < 10){
SCL_LOW();
twi_delay(twi_dcount);
SCL_HIGH();
unsigned int t=0; while(SCL_READ()==0 && (t++)<twi_clockStretchLimit); // twi_clockStretchLimit
twi_delay(twi_dcount);
}
return 0;
}
unsigned char twi_readFrom(unsigned char address, unsigned char* buf, unsigned int len, unsigned char sendStop){
unsigned int i;
if(!twi_write_start()) return 4;//line busy
if(!twi_write_byte(((address << 1) | 1) & 0xFF)) {
if (sendStop) twi_write_stop();
return 2;//received NACK on transmit of address
}
for(i=0; i<(len-1); i++) buf[i] = twi_read_byte(false);
buf[len-1] = twi_read_byte(true);
if(sendStop) twi_write_stop();
i = 0;
while(SDA_READ() == 0 && (i++) < 10){
SCL_LOW();
twi_delay(twi_dcount);
SCL_HIGH();
unsigned int t=0; while(SCL_READ()==0 && (t++)<twi_clockStretchLimit); // twi_clockStretchLimit
twi_delay(twi_dcount);
}
return 0;
}
uint8_t twi_status() {
if (SCL_READ() == 0)
return I2C_SCL_HELD_LOW; // SCL held low by another device, no procedure available to recover
int clockCount = 20;
while (SDA_READ() == 0 && clockCount-- > 0) { // if SDA low, read the bits slaves have to sent to a max
twi_read_bit();
if (SCL_READ() == 0) {
return I2C_SCL_HELD_LOW_AFTER_READ; // I2C bus error. SCL held low beyond slave clock stretch time
}
}
if (SDA_READ() == 0)
return I2C_SDA_HELD_LOW; // I2C bus error. SDA line held low by slave/another_master after n bits.
if (!twi_write_start())
return I2C_SDA_HELD_LOW_AFTER_INIT; // line busy. SDA again held low by another device. 2nd master?
return I2C_OK;
}
uint8_t twi_transmit(const uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if (length > TWI_BUFFER_LENGTH) {
return 1;
}
// ensure we are currently a slave transmitter
if (twi_state != TWI_STX) {
return 2;
}
// set length and copy data into tx buffer
twi_txBufferLength = length;
for (i = 0; i < length; ++i) {
twi_txBuffer[i] = data[i];
}
return 0;
}
void twi_attachSlaveRxEvent( void (*function)(uint8_t*, size_t) )
{
twi_onSlaveReceive = function;
}
void twi_attachSlaveTxEvent( void (*function)(void) )
{
twi_onSlaveTransmit = function;
}
void ICACHE_RAM_ATTR twi_reply(uint8_t ack)
{
// transmit master read ready signal, with or without ack
if (ack) {
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
SCL_HIGH(); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
} else {
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
SCL_HIGH(); // _BV(TWINT)
twi_ack = 0; // ~_BV(TWEA)
}
}
void ICACHE_RAM_ATTR twi_stop(void)
{
// send stop condition
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
SCL_HIGH(); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
twi_delay(5); // Maybe this should be here
SDA_HIGH(); // _BV(TWSTO)
// update twi state
twi_state = TWI_READY;
}
void ICACHE_RAM_ATTR twi_releaseBus(void)
{
// release bus
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
SCL_HIGH(); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
SDA_HIGH();
// update twi state
twi_state = TWI_READY;
}
void ICACHE_RAM_ATTR twi_onTwipEvent(uint8_t status)
{
switch(status) {
// Slave Receiver
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
// enter slave receiver mode
twi_state = TWI_SRX;
// indicate that rx buffer can be overwritten and ack
twi_rxBufferIndex = 0;
twi_reply(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
// if there is still room in the rx buffer
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
// put byte in buffer and ack
twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
twi_reply(1);
}else{
// otherwise nack
twi_reply(0);
}
break;
case TW_SR_STOP: // stop or repeated start condition received
// put a null char after data if there's room
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
twi_rxBuffer[twi_rxBufferIndex] = '\0';
}
// callback to user-defined callback over event task to allow for non-RAM-residing code
//twi_rxBufferLock = true; // This may be necessary
ets_post(EVENTTASK_QUEUE_PRIO, TWI_SIG_RX, twi_rxBufferIndex);
// since we submit rx buffer to "wire" library, we can reset it
twi_rxBufferIndex = 0;
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
// nack back at master
twi_reply(0);
break;
// Slave Transmitter
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// enter slave transmitter mode
twi_state = TWI_STX;
// ready the tx buffer index for iteration
twi_txBufferIndex = 0;
// set tx buffer length to be zero, to verify if user changes it
twi_txBufferLength = 0;
// callback to user-defined callback over event task to allow for non-RAM-residing code
// request for txBuffer to be filled and length to be set
// note: user must call twi_transmit(bytes, length) to do this
ets_post(EVENTTASK_QUEUE_PRIO, TWI_SIG_TX, 0);
break;
case TW_ST_DATA_ACK: // byte sent, ack returned
// copy data to output register
TWDR = twi_txBuffer[twi_txBufferIndex++];
bitCount = 8;
bitCount--;
(twi_data & 0x80) ? SDA_HIGH() : SDA_LOW();
twi_data <<= 1;
// if there is more to send, ack, otherwise nack
if(twi_txBufferIndex < twi_txBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// leave slave receiver state
twi_releaseBus();
break;
// All
case TW_NO_INFO: // no state information
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_error = TW_BUS_ERROR;
twi_stop();
break;
}
}
void ICACHE_RAM_ATTR onTimer()
{
twi_releaseBus();
twip_status = TW_BUS_ERROR;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_BUS_ERR;
}
static void eventTask(ETSEvent *e)
{
if (e == NULL) {
return;
}
switch (e->sig)
{
case TWI_SIG_TX:
twi_onSlaveTransmit();
// if they didn't change buffer & length, initialize it
if (twi_txBufferLength == 0) {
twi_txBufferLength = 1;
twi_txBuffer[0] = 0x00;
}
// Initiate transmission
twi_onTwipEvent(TW_ST_DATA_ACK);
break;
case TWI_SIG_RX:
// ack future responses and leave slave receiver state
twi_releaseBus();
twi_onSlaveReceive(twi_rxBuffer, e->par);
break;
}
}
void ICACHE_RAM_ATTR onSclChange(void)
{
static uint8_t sda;
static uint8_t scl;
sda = SDA_READ();
scl = SCL_READ();
twip_status = 0xF8; // reset TWI status
switch (twip_state)
{
case TWIP_IDLE:
case TWIP_WAIT_STOP:
case TWIP_BUS_ERR:
// ignore
break;
case TWIP_START:
case TWIP_REP_START:
case TWIP_SLA_W:
case TWIP_READ:
if (!scl) {
// ignore
} else {
bitCount--;
twi_data <<= 1;
twi_data |= sda;
if (bitCount != 0) {
// continue
} else {
twip_state = TWIP_SEND_ACK;
}
}
break;
case TWIP_SEND_ACK:
if (scl) {
// ignore
} else {
if (twip_mode == TWIPM_IDLE) {
if ((twi_data & 0xFE) != twi_addr) {
// ignore
} else {
SDA_LOW();
}
} else {
if (!twi_ack) {
// ignore
} else {
SDA_LOW();
}
}
twip_state = TWIP_WAIT_ACK;
}
break;
case TWIP_WAIT_ACK:
if (scl) {
// ignore
} else {
if (twip_mode == TWIPM_IDLE) {
if ((twi_data & 0xFE) != twi_addr) {
SDA_HIGH();
twip_state = TWIP_WAIT_STOP;
} else {
SCL_LOW(); // clock stretching
SDA_HIGH();
twip_mode = TWIPM_ADDRESSED;
if (!(twi_data & 0x01)) {
twip_status = TW_SR_SLA_ACK;
twi_onTwipEvent(twip_status);
bitCount = 8;
twip_state = TWIP_SLA_W;
} else {
twip_status = TW_ST_SLA_ACK;
twi_onTwipEvent(twip_status);
twip_state = TWIP_SLA_R;
}
}
} else {
SCL_LOW(); // clock stretching
SDA_HIGH();
if (!twi_ack) {
twip_status = TW_SR_DATA_NACK;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_WAIT_STOP;
} else {
twip_status = TW_SR_DATA_ACK;
twi_onTwipEvent(twip_status);
bitCount = 8;
twip_state = TWIP_READ;
}
}
}
break;
case TWIP_SLA_R:
case TWIP_WRITE:
if (scl) {
// ignore
} else {
bitCount--;
(twi_data & 0x80) ? SDA_HIGH() : SDA_LOW();
twi_data <<= 1;
if (bitCount != 0) {
// continue
} else {
twip_state = TWIP_REC_ACK;
}
}
break;
case TWIP_REC_ACK:
if (scl) {
// ignore
} else {
SDA_HIGH();
twip_state = TWIP_READ_ACK;
}
break;
case TWIP_READ_ACK:
if (!scl) {
// ignore
} else {
twi_ack_rec = !sda;
twip_state = TWIP_RWAIT_ACK;
}
break;
case TWIP_RWAIT_ACK:
if (scl) {
// ignore
} else {
SCL_LOW(); // clock stretching
if (twi_ack && twi_ack_rec) {
twip_status = TW_ST_DATA_ACK;
twi_onTwipEvent(twip_status);
twip_state = TWIP_WRITE;
} else {
// we have no more data to send and/or the master doesn't want anymore
twip_status = twi_ack_rec ? TW_ST_LAST_DATA : TW_ST_DATA_NACK;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_WAIT_STOP;
}
}
break;
default:
break;
}
}
void ICACHE_RAM_ATTR onSdaChange(void)
{
static uint8_t sda;
static uint8_t scl;
sda = SDA_READ();
scl = SCL_READ();
switch (twip_state)
{
case TWIP_IDLE:
if (!scl) {
// DATA - ignore
} else if (sda) {
// STOP - ignore
} else {
// START
bitCount = 8;
twip_state = TWIP_START;
ets_timer_arm_new(&timer, twi_timeout_ms, false, true); // Once, ms
}
break;
case TWIP_START:
case TWIP_REP_START:
case TWIP_SEND_ACK:
case TWIP_WAIT_ACK:
case TWIP_SLA_R:
case TWIP_REC_ACK:
case TWIP_READ_ACK:
case TWIP_RWAIT_ACK:
case TWIP_WRITE:
if (!scl) {
// DATA - ignore
} else {
// START or STOP
SDA_HIGH(); // Should not be necessary
twip_status = TW_BUS_ERROR;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_BUS_ERR;
}
break;
case TWIP_WAIT_STOP:
case TWIP_BUS_ERR:
if (!scl) {
// DATA - ignore
} else {
if (sda) {
// STOP
SCL_LOW(); // clock stretching
ets_timer_disarm(&timer);
twip_state = TWIP_IDLE;
twip_mode = TWIPM_IDLE;
SCL_HIGH();
} else {
// START
if (twip_state == TWIP_BUS_ERR) {
// ignore
} else {
bitCount = 8;
twip_state = TWIP_REP_START;
ets_timer_arm_new(&timer, twi_timeout_ms, false, true); // Once, ms
}
}
}
break;
case TWIP_SLA_W:
case TWIP_READ:
if (!scl) {
// DATA - ignore
} else {
// START or STOP
if (bitCount != 7) {
// inside byte transfer - error
twip_status = TW_BUS_ERROR;
twi_onTwipEvent(twip_status);
twip_mode = TWIPM_WAIT;
twip_state = TWIP_BUS_ERR;
} else {
// during first bit in byte transfer - ok
SCL_LOW(); // clock stretching
twip_status = TW_SR_STOP;
twi_onTwipEvent(twip_status);
if (sda) {
// STOP
ets_timer_disarm(&timer);
twip_state = TWIP_IDLE;
twip_mode = TWIPM_IDLE;
} else {
// START
bitCount = 8;
ets_timer_arm_new(&timer, twi_timeout_ms, false, true); // Once, ms
twip_state = TWIP_REP_START;
twip_mode = TWIPM_IDLE;
}
}
}
break;
default:
break;
}
}
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