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Reducing excessive I2C timeout #494

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Merged
pennam merged 1 commit into from
Dec 4, 2025
Merged

Reducing excessive I2C timeout #494

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25 changes: 15 additions & 10 deletions libraries/Wire/Wire.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ TwoWire::TwoWire(int scl, int sda, WireAddressMode_t am /*= ADDRESS_MODE_7_BITS*
is_master(true),
is_sci(false),
address_mode(am),
timeout(1000),
timeout_us(1000),
transmission_begun(false),
data_too_long(false),
rx_index(0),
Expand Down Expand Up @@ -465,7 +465,7 @@ void TwoWire::end(void) {


/* -------------------------------------------------------------------------- */
uint8_t TwoWire::read_from(uint8_t address, uint8_t* data, uint8_t length, unsigned int timeout_ms, bool sendStop) {
uint8_t TwoWire::read_from(uint8_t address, uint8_t* data, uint8_t length, unsigned int timeout_us, bool sendStop) {
/* -------------------------------------------------------------------------- */
/* ??? does this function make sense only for MASTER ???? */

Expand All @@ -480,8 +480,8 @@ uint8_t TwoWire::read_from(uint8_t address, uint8_t* data, uint8_t length, unsig
err = m_read(&m_i2c_ctrl,data,length,!sendStop);
}
}
uint32_t const start = millis();
while(((millis() - start) < timeout_ms) && bus_status == WIRE_STATUS_UNSET && err == FSP_SUCCESS) {
uint32_t const start = micros();
while(((micros() - start) < timeout_us) && bus_status == WIRE_STATUS_UNSET && err == FSP_SUCCESS) {

}
}
Expand All @@ -494,7 +494,7 @@ uint8_t TwoWire::read_from(uint8_t address, uint8_t* data, uint8_t length, unsig
}

/* -------------------------------------------------------------------------- */
uint8_t TwoWire::write_to(uint8_t address, uint8_t* data, uint8_t length, unsigned int timeout_ms, bool sendStop) {
uint8_t TwoWire::write_to(uint8_t address, uint8_t* data, uint8_t length, unsigned int timeout_us, bool sendStop) {
/* -------------------------------------------------------------------------- */
uint8_t rv = END_TX_OK;
fsp_err_t err = FSP_ERR_ASSERTION;
Expand All @@ -508,8 +508,8 @@ uint8_t TwoWire::write_to(uint8_t address, uint8_t* data, uint8_t length, unsign
err = m_write(&m_i2c_ctrl,data,length,!sendStop);
}
}
uint32_t const start = millis();
while(((millis() - start) < timeout_ms) && bus_status == WIRE_STATUS_UNSET && err == FSP_SUCCESS) {
uint32_t const start = micros();
while(((micros() - start) < timeout_us) && bus_status == WIRE_STATUS_UNSET && err == FSP_SUCCESS) {

}

Expand Down Expand Up @@ -642,7 +642,7 @@ void TwoWire::beginTransmission(int address) {
/* -------------------------------------------------------------------------- */
uint8_t TwoWire::endTransmission(bool sendStop) {
/* -------------------------------------------------------------------------- */
uint8_t ret = write_to(master_tx_address, tx_buffer, tx_index, timeout, sendStop);
uint8_t ret = write_to(master_tx_address, tx_buffer, tx_index, timeout_us, sendStop);
transmission_begun = false;
return ret;
}
Expand Down Expand Up @@ -687,7 +687,7 @@ size_t TwoWire::requestFrom(uint8_t address, size_t quantity, uint32_t iaddress,
quantity = I2C_BUFFER_LENGTH;
}
// perform blocking read into buffer
uint8_t read = read_from(address, rx_buffer, quantity, timeout, sendStop);
uint8_t read = read_from(address, rx_buffer, quantity, timeout_us, sendStop);
// set rx buffer iterator vars
rx_index = read;
rx_extract_index = 0;
Expand Down Expand Up @@ -835,7 +835,12 @@ void TwoWire::flush(void) {
while(bus_status != WIRE_STATUS_TX_COMPLETED && bus_status != WIRE_STATUS_TRANSACTION_ABORTED) {}
}


/* -------------------------------------------------------------------------- */
void TwoWire::setWireTimeout(unsigned int _timeout_us, bool reset_on_timeout) {
/* -------------------------------------------------------------------------- */
(void)reset_on_timeout;
timeout_us = _timeout_us;
}


#if WIRE_HOWMANY > 0
Expand Down
23 changes: 20 additions & 3 deletions libraries/Wire/Wire.h
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,16 @@ class TwoWire : public arduino::HardwareI2C {
void onRequest( void (*)(void) );

void setBusStatus(WireStatus_t);
/* set timeout in us for I2C communication (default is 1000 us)
the second parameter has been added for compatibility but it has no effect

Please note: on uno R4 (both minima and wifi) the timeout has only effect
when I2C pull up are NOT mounted (if they are mounted, as they should, the
I2C is immediately stopped due to a NACK and so the timeout has no effect).
On Portenta C33 however timeout is used in both cases (with or without
I2C pull up) because at low level the NACK does not immediately stop the I2C
communication. */
void setWireTimeout(unsigned int _timeout_us = 1000, bool reset_on_timeout = false);

inline size_t write(unsigned long n) { return write((uint8_t)n); }
inline size_t write(long n) { return write((uint8_t)n); }
Expand Down Expand Up @@ -168,8 +178,15 @@ class TwoWire : public arduino::HardwareI2C {
int channel;
bool is_sci;
WireAddressMode_t address_mode;

unsigned int timeout;
/* I2C timeout in micro seconds

Please note: on uno R4 (both minima and wifi) the timeout has only effect
when I2C pull up are NOT mounted (if they are mounted, as they should, the
I2C is immediately stopped due to a NACK and so the timeout has no effect).
On Portenta C33 however timeout is used in both cases (with or without
I2C pull up) because at low level the NACK does not immediately stop the I2C
communication. */
unsigned int timeout_us;
bool transmission_begun;
bool data_too_long;

Expand Down Expand Up @@ -235,4 +252,4 @@ extern TwoWire Wire3;
#endif

#endif
#endif
#endif