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norbert-walter / esp32-nmea2000-obp60

nmea2000 gateway with ESP32
GNU General Public License v2.0
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Boot problem if use external I2C devices #46

Closed norbert-walter closed 2 years ago

norbert-walter commented 2 years ago

If you use external I2C modules that don't use 3.3V signal level, it can cause boot problems. The buzzer, the backlight, the flash LED and the GPS module may not work because the MCP23017 can no longer be addressed and the 3.3V and 5.0V can therefore not be switched on. The problem is actually not a hardware problem but rather a problem caused by the wrong hardware being connected to the I2C bus. Great care is required when using the I2C bus with external modules, as this can affect the overall stability of the system. In particular, the SDA and SCL inputs must never be connected to 12V! This will inevitably destroy the ESP32.

norbert-walter commented 2 years ago

Solution:

Use only modules with 3.3V voltage converter on the PCB and Chips with 3.3V TTL logic level. Any modules without voltage converter are 5.0V tolerant but the TTL level is than 5.0V! Please check the modules for the correct TTL level for 3.3V.