Unable to use I2C
ChristopheLaurent opened this issue · 0 comments
I got the T5-2.13 and I try to connect a SCD41 CO2 sensor using I2C. This is basically the same thing as in this tutorial: https://github.com/Sensirion/arduino-ble-gadget/blob/master/documents/SCD4x_BLE_Gadget_Tutorial.md .
The classic scan of I2C bus shows that my sensor is there at address 0x67. So far so good. But when the T5-2.13 is sending commands to the sensor, I get error message "Error trying to execute readMeasurement(): Received NACK on transmit of address". I get this error without any code related to SPI or Ink screen. If I plug a regular ESP32 dev kit instead of the the T5-2.13 , then run the same code on the regular ESP32 dev kit, it works very well, without any I2C error.
I did not put any pull up resistor in both cases, because there is already one on the sensor breakout. In both cases I powered the T5-2.13 and the ESP32 dev kit with USB from my computer.
The peak current @ 3.3V for the SCD41 is 205 mA. Is this issue related to the 3V3 LDO on the T5-2.13 that could be too weak ? Looking at the diagram of the T5-2.13 ( https://github.com/re-innovation/TTGO_EPaper/blob/master/TTGO_Datasheets/T5_V2.3.pdf ) I noticed 2 LDOs, one for 3V3 and one for VCC_IO, but I can only see 3V3 on the pinout.
Any suggestion ?
[EDIT 1] I just tried using another (simpler) sensor: INA 219 DC Current monitor. It works well with regular ESP32 dev kit, not with the T5-2.13: It fails calling ina219.begin(). I then tried using 2 other pins for I2C: pin 25 & pin 26. Still the same problem, it works on ESP32 dev kit but fails the same way on the T5-2.13.
Did someone already manage to use I2C on T5-2.13 ? Could you please provide an example of T5-2.13 displaying ambiant temperature from an I2C sensor, or something along these lines ?
[Edit 2] I eventually found the cause of my problem: solder ! Please close this issue...