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mhsw-espurna/code/espurna/i2c.ino

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/*
I2C MODULE
Copyright (C) 2017-2019 by Xose Pérez <xose dot perez at gmail dot com>
*/
#if I2C_SUPPORT
unsigned int _i2c_locked[16] = {0};
#if I2C_USE_BRZO
unsigned long _i2c_scl_frequency = 0;
#endif
// -----------------------------------------------------------------------------
// Private
// -----------------------------------------------------------------------------
int _i2cGetSDA() {
return getSetting("i2cSDA", I2C_SDA_PIN);
}
int _i2cGetSCL() {
return getSetting("i2cSCL", I2C_SCL_PIN);
}
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);
nice_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--;
nice_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
// ---------------------------------------------------------------------
#if I2C_USE_BRZO
void i2c_wakeup(uint8_t address) {
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_end_transaction();
}
uint8_t i2c_write_uint8(uint8_t address, uint8_t value) {
uint8_t buffer[1] = {value};
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_write_uint8(buffer, 1, false);
return brzo_i2c_end_transaction();
}
uint8_t i2c_write_buffer(uint8_t address, uint8_t * buffer, size_t len) {
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_write_uint8(buffer, len, false);
return brzo_i2c_end_transaction();
}
uint8_t i2c_read_uint8(uint8_t address) {
uint8_t buffer[1] = {reg};
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_read(buffer, 1, false);
brzo_i2c_end_transaction();
return buffer[0];
};
uint8_t i2c_read_uint8(uint8_t address, uint8_t reg) {
uint8_t buffer[1] = {reg};
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_write_uint8(buffer, 1, false);
brzo_i2c_read(buffer, 1, false);
brzo_i2c_end_transaction();
return buffer[0];
};
uint16_t i2c_read_uint16(uint8_t address) {
uint8_t buffer[2] = {reg, 0};
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_read(buffer, 2, false);
brzo_i2c_end_transaction();
return (buffer[0] * 256) | buffer[1];
};
uint16_t i2c_read_uint16(uint8_t address, uint8_t reg) {
uint8_t buffer[2] = {reg, 0};
brzo_i2c_start_transaction(_address, _i2c_scl_frequency);
brzo_i2c_write_uint8(buffer, 1, false);
brzo_i2c_read(buffer, 2, false);
brzo_i2c_end_transaction();
return (buffer[0] * 256) | buffer[1];
};
void i2c_read_buffer(uint8_t address, uint8_t * buffer, size_t len) {
brzo_i2c_start_transaction(address, _i2c_scl_frequency);
brzo_i2c_read(buffer, len, false);
brzo_i2c_end_transaction();
}
#else // not I2C_USE_BRZO
void i2c_wakeup(uint8_t address) {
Wire.beginTransmission((uint8_t) address);
Wire.endTransmission();
}
uint8_t i2c_write_uint8(uint8_t address, uint8_t value) {
Wire.beginTransmission((uint8_t) address);
Wire.write((uint8_t) value);
return Wire.endTransmission();
}
uint8_t i2c_write_buffer(uint8_t address, uint8_t * buffer, size_t len) {
Wire.beginTransmission((uint8_t) address);
Wire.write(buffer, len);
return Wire.endTransmission();
}
uint8_t i2c_read_uint8(uint8_t address) {
uint8_t value;
Wire.beginTransmission((uint8_t) address);
Wire.requestFrom((uint8_t) address, (uint8_t) 1);
value = Wire.read();
Wire.endTransmission();
return value;
};
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) {
uint16_t value;
Wire.beginTransmission((uint8_t) address);
Wire.requestFrom((uint8_t) address, (uint8_t) 2);
value = (Wire.read() * 256) | 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() * 256) | Wire.read();
Wire.endTransmission();
return value;
};
void i2c_read_buffer(uint8_t address, uint8_t * buffer, size_t len) {
Wire.beginTransmission((uint8_t) address);
Wire.requestFrom(address, (uint8_t) len);
for (size_t i=0; i<len; i++) buffer[i] = Wire.read();
Wire.endTransmission();
}
#endif // I2C_USE_BRZO
uint8_t i2c_write_uint8(uint8_t address, uint8_t reg, uint8_t value) {
uint8_t buffer[2] = {reg, value};
return i2c_write_buffer(address, buffer, 2);
}
uint8_t i2c_write_uint8(uint8_t address, uint8_t reg, uint8_t value1, uint8_t value2) {
uint8_t buffer[3] = {reg, value1, value2};
return i2c_write_buffer(address, buffer, 3);
}
uint8_t i2c_write_uint16(uint8_t address, uint8_t reg, uint16_t value) {
uint8_t buffer[3];
buffer[0] = reg;
buffer[1] = (value >> 8) & 0xFF;
buffer[2] = (value >> 0) & 0xFF;
return i2c_write_buffer(address, buffer, 3);
}
uint8_t i2c_write_uint16(uint8_t address, uint16_t value) {
uint8_t buffer[2];
buffer[0] = (value >> 8) & 0xFF;
buffer[1] = (value >> 0) & 0xFF;
return i2c_write_buffer(address, buffer, 2);
}
uint16_t i2c_read_uint16_le(uint8_t address, uint8_t reg) {
uint16_t temp = i2c_read_uint16(address, reg);
return (temp / 256) | (temp * 256);
};
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() {
DEBUG_MSG_P(
PSTR("[I2C] Clear bus (response: %d)\n"),
_i2cClearbus(_i2cGetSDA(), _i2cGetSCL())
);
}
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"));
}
#if TERMINAL_SUPPORT
void _i2cInitCommands() {
terminalRegisterCommand(F("I2C.SCAN"), [](Embedis* e) {
i2cScan();
terminalOK();
});
terminalRegisterCommand(F("I2C.CLEAR"), [](Embedis* e) {
i2cClearBus();
terminalOK();
});
}
#endif // TERMINAL_SUPPORT
void i2cSetup() {
const auto sda = _i2cGetSDA();
const auto scl = _i2cGetSCL();
#if I2C_USE_BRZO
auto cst = getSetting("i2cCST", I2C_CLOCK_STRETCH_TIME);
_i2c_scl_frequency = getSetting("i2cFreq", I2C_SCL_FREQUENCY);
brzo_i2c_setup(sda, scl, cst);
#else
Wire.begin(sda, scl);
#endif
DEBUG_MSG_P(PSTR("[I2C] Using GPIO%02d for SDA and GPIO%02d for SCL\n"), sda, scl);
#if TERMINAL_SUPPORT
_i2cInitCommands();
#endif
#if I2C_CLEAR_BUS
i2cClearBus();
#endif
#if I2C_PERFORM_SCAN
i2cScan();
#endif
}
#endif