You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
162 lines
5.3 KiB
162 lines
5.3 KiB
/*
|
|
|
|
I2C MODULE
|
|
|
|
Copyright (C) 2017 by Xose Pérez <xose dot perez at gmail dot com>
|
|
|
|
*/
|
|
|
|
#if I2C_SUPPORT
|
|
|
|
#if I2C_USE_BRZO
|
|
#include "brzo_i2c.h"
|
|
unsigned long _i2c_scl_frequency = 0;
|
|
#else
|
|
#include "Wire.h"
|
|
#endif
|
|
|
|
// -----------------------------------------------------------------------------
|
|
// Private
|
|
// -----------------------------------------------------------------------------
|
|
|
|
int _i2cClearbus(int sda, int scl) {
|
|
|
|
#if defined(TWCR) && defined(TWEN)
|
|
// Disable the Atmel 2-Wire interface so we can control the SDA and SCL pins directly
|
|
TWCR &= ~(_BV(TWEN));
|
|
#endif
|
|
|
|
// Make SDA (data) and SCL (clock) pins inputs with pullup
|
|
pinMode(sda, INPUT_PULLUP);
|
|
pinMode(scl, INPUT_PULLUP);
|
|
|
|
delay(2500);
|
|
// Wait 2.5 secs. This is strictly only necessary on the first power
|
|
// up of the DS3231 module to allow it to initialize properly,
|
|
// but is also assists in reliable programming of FioV3 boards as it gives the
|
|
// IDE a chance to start uploaded the program
|
|
// before existing sketch confuses the IDE by sending Serial data.
|
|
|
|
// If it is held low the device cannot become the I2C master
|
|
// I2C bus error. Could not clear SCL clock line held low
|
|
boolean scl_low = (digitalRead(scl) == LOW);
|
|
if (scl_low) return 1;
|
|
|
|
|
|
boolean sda_low = (digitalRead(sda) == LOW);
|
|
int clockCount = 20; // > 2x9 clock
|
|
|
|
// While SDA is low for at most 20 cycles
|
|
while (sda_low && (clockCount > 0)) {
|
|
|
|
clockCount--;
|
|
|
|
// Note: I2C bus is open collector so do NOT drive SCL or SDA high
|
|
pinMode(scl, INPUT); // release SCL pullup so that when made output it will be LOW
|
|
pinMode(scl, OUTPUT); // then clock SCL Low
|
|
delayMicroseconds(10); // for >5uS
|
|
pinMode(scl, INPUT); // release SCL LOW
|
|
pinMode(scl, INPUT_PULLUP); // turn on pullup resistors again
|
|
// do not force high as slave may be holding it low for clock stretching
|
|
|
|
delayMicroseconds(10); // The >5uS is so that even the slowest I2C devices are handled
|
|
|
|
// loop waiting for SCL to become high only wait 2sec
|
|
scl_low = (digitalRead(scl) == LOW);
|
|
int counter = 20;
|
|
while (scl_low && (counter > 0)) {
|
|
counter--;
|
|
delay(100);
|
|
scl_low = (digitalRead(scl) == LOW);
|
|
}
|
|
|
|
// If still low after 2 sec error
|
|
// I2C bus error. Could not clear. SCL clock line held low by slave clock stretch for >2sec
|
|
if (scl_low) return 2;
|
|
|
|
sda_low = (digitalRead(sda) == LOW); // and check SDA input again and loop
|
|
|
|
}
|
|
|
|
// If still low
|
|
// I2C bus error. Could not clear. SDA data line held low
|
|
if (sda_low) return 3;
|
|
|
|
// Pull SDA line low for "start" or "repeated start"
|
|
pinMode(sda, INPUT); // remove pullup
|
|
pinMode(sda, OUTPUT); // and then make it LOW i.e. send an I2C Start or Repeated start control
|
|
|
|
// When there is only one I2C master a "start" or "repeat start" has the same function as a "stop" and clears the bus
|
|
// A Repeat Start is a Start occurring after a Start with no intervening Stop.
|
|
|
|
delayMicroseconds(10); // wait >5uS
|
|
pinMode(sda, INPUT); // remove output low
|
|
pinMode(sda, INPUT_PULLUP); // and make SDA high i.e. send I2C STOP control.
|
|
|
|
delayMicroseconds(10); // wait >5uS
|
|
pinMode(sda, INPUT); // and reset pins as tri-state inputs which is the default state on reset
|
|
pinMode(scl, INPUT);
|
|
|
|
// Everything OK
|
|
return 0;
|
|
|
|
}
|
|
|
|
// -----------------------------------------------------------------------------
|
|
// Utils
|
|
// -----------------------------------------------------------------------------
|
|
|
|
void i2cClearBus() {
|
|
unsigned char sda = getSetting("i2cSDA", I2C_SDA_PIN).toInt();
|
|
unsigned char scl = getSetting("i2cSCL", I2C_SCL_PIN).toInt();
|
|
DEBUG_MSG_P(PSTR("[I2C] Clear bus (response: %d)\n"), _i2cClearbus(sda, scl));
|
|
}
|
|
|
|
bool i2cCheck(unsigned char address) {
|
|
#if I2C_USE_BRZO
|
|
brzo_i2c_start_transaction(address, _i2c_scl_frequency);
|
|
brzo_i2c_ACK_polling(1000);
|
|
return brzo_i2c_end_transaction();
|
|
#else
|
|
Wire.beginTransmission(address);
|
|
return Wire.endTransmission();
|
|
#endif
|
|
}
|
|
|
|
unsigned char i2cFindFirst(size_t size, unsigned char * addresses) {
|
|
for (unsigned char i=0; i<size; i++) {
|
|
if (i2cCheck(addresses[i]) == 0) return addresses[i];
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void i2cScan() {
|
|
unsigned char nDevices = 0;
|
|
for (unsigned char address = 1; address < 127; address++) {
|
|
unsigned char error = i2cCheck(address);
|
|
if (error == 0) {
|
|
DEBUG_MSG_P(PSTR("[I2C] Device found at address 0x%02X\n"), address);
|
|
nDevices++;
|
|
}
|
|
}
|
|
if (nDevices == 0) DEBUG_MSG_P(PSTR("[I2C] No devices found\n"));
|
|
}
|
|
|
|
void i2cSetup() {
|
|
|
|
unsigned char sda = getSetting("i2cSDA", I2C_SDA_PIN).toInt();
|
|
unsigned char scl = getSetting("i2cSCL", I2C_SCL_PIN).toInt();
|
|
|
|
#if I2C_USE_BRZO
|
|
unsigned long cst = getSetting("i2cCST", I2C_CLOCK_STRETCH_TIME).toInt();
|
|
_i2c_scl_frequency = getSetting("i2cFreq", I2C_SCL_FREQUENCY).toInt();
|
|
brzo_i2c_setup(sda, scl, cst);
|
|
#else
|
|
Wire.begin(sda, scl);
|
|
#endif
|
|
|
|
DEBUG_MSG_P(PSTR("[I2C] Using GPIO%d for SDA and GPIO%d for SCL\n"), sda, scl);
|
|
|
|
}
|
|
|
|
#endif
|