|
|
- /*
-
- I2C MODULE
-
- Copyright (C) 2017-2018 by Xose Pérez <xose dot perez at gmail dot com>
-
- */
-
- #if I2C_SUPPORT
-
- unsigned int _i2c_locked[16] = {0};
-
- #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;
-
- }
-
- // ---------------------------------------------------------------------
- // I2C API
- // ---------------------------------------------------------------------
-
- void i2c_write_uint8(uint8_t address, uint8_t reg, uint8_t value) {
- Wire.beginTransmission((uint8_t) address);
- Wire.write((uint8_t) reg);
- Wire.write((uint8_t) value);
- Wire.endTransmission();
- }
-
- uint8_t i2c_read_uint8(uint8_t address, uint8_t reg) {
- uint8_t value;
- Wire.beginTransmission((uint8_t) address);
- Wire.write((uint8_t) reg);
- Wire.endTransmission();
- Wire.requestFrom((uint8_t)address, (uint8_t) 1);
- value = Wire.read();
- Wire.endTransmission();
- return value;
- };
-
- uint16_t i2c_read_uint16(uint8_t address, uint8_t reg) {
- uint16_t value;
- Wire.beginTransmission((uint8_t) address);
- Wire.write((uint8_t) reg);
- Wire.endTransmission();
- Wire.requestFrom((uint8_t) address, (uint8_t) 2);
- value = (Wire.read() << 8) | Wire.read();
- Wire.endTransmission();
- return value;
- };
-
- uint16_t i2c_read_uint16_le(uint8_t address, uint8_t reg) {
- uint16_t temp = i2c_read_uint16(address, reg);
- return (temp >> 8) | (temp << 8);
- };
-
- int16_t i2c_read_int16(uint8_t address, uint8_t reg) {
- return (int16_t) i2c_read_uint16(address, reg);
- };
-
- int16_t i2c_read_int16_le(uint8_t address, uint8_t reg) {
- return (int16_t) i2c_read_uint16_le(address, reg);
- };
-
- // -----------------------------------------------------------------------------
- // 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
- }
-
- bool i2cGetLock(unsigned char address) {
- unsigned char index = address / 8;
- unsigned char mask = 1 << (address % 8);
- if (_i2c_locked[index] & mask) return false;
- _i2c_locked[index] = _i2c_locked[index] | mask;
- DEBUG_MSG_P(PSTR("[I2C] Address 0x%02X locked\n"), address);
- return true;
- }
-
- bool i2cReleaseLock(unsigned char address) {
- unsigned char index = address / 8;
- unsigned char mask = 1 << (address % 8);
- if (_i2c_locked[index] & mask) {
- _i2c_locked[index] = _i2c_locked[index] & ~mask;
- return true;
- }
- return false;
- }
-
- unsigned char i2cFind(size_t size, unsigned char * addresses, unsigned char &start) {
- for (unsigned char i=start; i<size; i++) {
- if (i2cCheck(addresses[i]) == 0) {
- start = i;
- return addresses[i];
- }
- }
- return 0;
- }
-
- unsigned char i2cFind(size_t size, unsigned char * addresses) {
- unsigned char start = 0;
- return i2cFind(size, addresses, start);
- }
-
- unsigned char i2cFindAndLock(size_t size, unsigned char * addresses) {
- unsigned char start = 0;
- unsigned char address = 0;
- while (address = i2cFind(size, addresses, start)) {
- if (i2cGetLock(address)) break;
- start++;
- }
- return address;
- }
-
- 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%u for SDA and GPIO%u for SCL\n"), sda, scl);
-
- }
-
- #endif
|