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;
}
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 uint8_t ICACHE_FLASH_ATTR twi_read_byte(bool nack)
{
uint8_t byte = 0;
uint8_t bit;
for (bit = 0; bit < 8; bit++)
byte = (byte << 1) | twi_read_bit();
twi_write_bit(nack);
return byte;
}
static bool ICACHE_FLASH_ATTR twi_write_byte(uint8_t byte)
{
uint8_t bit;
for (bit = 0; bit < 8; bit++) {
twi_write_bit(byte & 0x80);
byte <<= 1;
}
return !twi_read_bit();
//NACK, ACK
}
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;
}
