* First, send a command to the other device */ tWireTimeout(3000 /* us */, true /* reset_on_timeout */) Wire.begin() // join i2c bus (address optional for master) This timeout and such additional measures should be seen as a last line of defence, when possible the underlying cause should be fixed instead. checksums or reading back written values) and recover from them ( e.g. Additional measures might be needed to more reliably detect such issues ( e.g. So when a timeout happens, it is likely that some data previously read or written is also corrupted. In such situations there will often (also) be data corruption which doesn't result in a timeout or other error and remains undetected. These timeouts will prevent your sketch from locking up, but not solve these problems. Note that these timeouts are almost always an indication of an underlying problem, such as misbehaving devices, noise, insufficient shielding, or other electrical problems. On platforms that support it, these timeouts can help handle unexpected situations on the Wire bus, such as another device or a short-circuit that keeps the bus blocked indefinitely, or noise that looks like a start condition, making it look there is another master active that keeps the bus claimed. Sets the timeout for Wire transmissions in master mode. Code that needs to be portable across platforms and versions can use the WIRE_HAS_END macro, which is only defined when Wire.end() is available. This function was not available in the original version of the Wire library and might still not be available on all platforms.
To use the Wire library again after this, call Wire.begin() again. Wire.end() Descriptionĭisable the Wire library, reversing the effect of Wire.begin(). See the tWireTimeout function for more details.
It is recommended to always enable these timeouts when using the Wire library. Recent versions of the Wire library can use timeouts to prevent a lockup in the face of certain problems on the bus, but this is not enabled by default (yet) in current versions. Also, there's a fair chance that I've written this in too much detail or technically too complex for the novice audience, so feedback on that aspect is also welcome. I've tried to match the formatting (heading levels etc.) to the existing doc pages, but it's likely that this still needs some handwork to integrate. Please find a proposal for documentation below, comments welcome. While looking at the Wire docs at I noticed that the end() method is also not documented yet. Given there is no repository for the library reference, I'm going to report this here. Recently, some new timeout API methods were added to the AVR Wire library (see arduino/ArduinoCore-avr#42), which should be documented.
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