I suspect the only really correct way to handle this is to let the sketch specify custom timeout values (or perhaps specify the max clock stretching time, whether multi-master should be supported and if so, the max transaction time of other masters). Since transactions might be long, and repeated start can be used to chain multiple together, there is no real upper limit on how long the timeout should be to keep facilitating a multi-master situation. In a true multi-master situation, a transaction might need to wait for another master to finish their transaction, which will likely trigger such a hardcoded timeout.Slaves might be using clock stretching, which can erronously trigger a timeout if it is too short.However, just having hardcoded timeouts as most of these implementations (including my own) have is problematic, because: So adding timeouts is probably the only way to fix this.

The only way I've found to recover from this situation is to disable and re-enable the TWI hardware.

There is a arbitration lost interrupt that can detect the start of this state in some cases (but not the end). detecting that the hardware hasn't finished in reasonable time, so probably never started in the first place). no status bit or anything), other than detecting a timeout (i.e. When the hardware ends up in such a state, there is no way to actually detect this state (i.e. However, when there is no other master but just noise on the bus, this will probably never happen. Since I☬ is a multi-master bus, when the hardware detects an external start condition, or an arbitration error, it will assume there is another master active and hold off any bus activity until it sees a stop condition. One particular challenge I've found (but I'm not sure if it is really properly documented yet), is that the AVR TWI hardware is particularly sensitive to noise that makes it look like there is a second master on the bus. Looking at these, I suspect that the version by and my own might be the best starting points, but neither completely solve the problem AFAICS.

(This is a version I wrote for a customer to fix lockups, it was never published until now).Make Wire library error safe Arduino#2489.

Wire library set i2c clock speed