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xreef / PCF8574_library

PCF8574 library. i2c digital expander for Arduino, Raspberry Pi Pico and rp2040 boards, esp32, SMT32 and ESP8266. Can read write digital values with only 2 wire. Very simple to use and encoder support.
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Lockup on PCF8574::begin() on ESP32 due to unpaired beginTransmission() call #56

Closed avillacis closed 2 years ago

avillacis commented 2 years ago

When compiling and running a sketch under arduino-esp32 v1.0.6, the library works OK. However, when using v2.0.2 or later, the sketch locks up completely inside the PCF8574::begin() call.

By digging into the code, I found out that there is an unpaired beginTransmission() call on the _wire ptr, that is, a beginTransmission not paired with a corresponding endTransmission() call on the same instance:

The two conflicting calls to beginTransmission() are:

https://github.com/xreef/PCF8574_library/blob/59cf47ccff8b22c5a57b17ba3649b851f18bbe9d/PCF8574.cpp#L200

https://github.com/xreef/PCF8574_library/blob/59cf47ccff8b22c5a57b17ba3649b851f18bbe9d/PCF8574.cpp#L211

The single call to endTransmission(): https://github.com/xreef/PCF8574_library/blob/59cf47ccff8b22c5a57b17ba3649b851f18bbe9d/PCF8574.cpp#L219

In context: https://github.com/xreef/PCF8574_library/blob/59cf47ccff8b22c5a57b17ba3649b851f18bbe9d/PCF8574.cpp#L198-L220

If one of the two calls is removed (I chose the one at line 211), the sketch no longer locks up.

xreef commented 2 years ago

Thanks, @avillacis, I'm going to fix it in the next release. Thanks again Renzo

xreef commented 2 years ago

Thanks again