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@maidnl maidnl commented Sep 23, 2025

This PR takes care of issue #492 .
There was a default timeout of 1000 ms in I2C communication.
Timeout has been reduced to 1ms.
However (although this is not a standard Wire function) a setTimeout() function has been added to Wire class so that users can tune the value.

@per1234 per1234 added the topic: code Related to content of the project itself label Sep 23, 2025
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maidnl commented Sep 24, 2025

@per1234 I renamed the function according to the request, however please note that in the current implementation of Wire (at least in Core-Renesas) the Wire class is derived from HardwareI2C class, that is derived from Stream. And Stream has already setTimeout function.
void setTimeout(unsigned long timeout); // sets maximum milliseconds to wait for stream data, default is 1 second
In my opinion it is better to use setTimeout name which is in line with the current class derivation scheme.

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per1234 commented Sep 25, 2025

Stream has already setTimeout function.

That function has a different purpose from what is being implemented here.

Stream::setTimeout sets the timeout for the high level blocking functions of the Stream class (e.g., readBytes).

The function implemented here is setting a timeout for the low level communication. This is the reason why the function was intentionally given a distinct name in the AVR library, rather than shadowing the Stream class member, which would have made it impossible to set the Stream timeout.

@per1234 per1234 dismissed their stale review October 10, 2025 05:16

Requested change has been made. Thanks!

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As @HanzHager reported in #497 (comment), the parameter of the established setWireTimeout implementation is the timeout duration in microseconds:

https://docs.arduino.cc/language-reference/en/functions/communication/wire/setWireTimeout/#parameters

timeout in microseconds, if zero then timeout checking is disabled

However, in your proposal the argument is instead a timeout duration in milliseconds.

Please bring the function into compliance with the established standardized API for Wire library implementations.

…unction present on ArduinoCore-avr

- the first parameter now express the timeout in micro seconds (default 25000 us)
- the second parameter reset_on_timeout has been added for compatibility but has no effect on this core (default false)
- the default timeout (if setWireTimeout is not called) remains set to 1 ms (1000 us)
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  • setWireTimeout(0,false) should disable timeout.

  • the new PR changes the default timeout value from 1000ms to 25ms (as also my PR does). This is not fully backwards compatible.
    Maybe ok to keep 1000ms when setWireTimeout() is introduced, unless it is obvious that 1000ms is a bug.

  • setWireTimeout(), without parameters sets another arbitrary timeout value than the default one and it is not obvious what the default is and what the initial default value is
    In the full solution for setting the timeout, there are macros that could be used to show what the default value is.

  • define WIRE_DEFAULT_TIMEOUT to be the default timeout value

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I2C scan takes extremely long (~126 seconds) with Wire.endTransmission() on empty bus

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