When setting up I2C on the Nano, SDA and SCL are pulled high to 5V VCC. Therefore, the jumper to select VCC is not needed as it will always be 5V as default. On the other hand a jumper to exclusively connect A4 and A5 to either the I2C/Freq route or the NTC readout route should be added. Now The A4/A5 are permanently connected to GND via 10k which is probably not beneficial for reliable I2C comms
leloup314
commented
1 year ago
When setting up I2C on the Nano, SDA and SCL are pulled high to 5V VCC. Therefore, the jumper to select VCC is not needed as it will always be 5V as default. On the other hand a jumper to exclusively connect A4 and A5 to either the I2C/Freq route or the NTC readout route should be added. Now The A4/A5 are permanently connected to GND via 10k which is probably not beneficial for reliable I2C comms