ATmega328p I2C Communication Issue with MPU6050: No Response on SDA/SCL Lines

Hi everyone!

I am currently developing an early phase prototype together with two friends. The board contains an ATmega328p-AU, an MPU6050 and MFRC522. We are able to both boatload and load sketches on the ATmega328p and also communicate with the MFRC522, but sadly we are not able to Full Schematic.PNG MPU6050 schematic.PNG PCB layout.jpg communicate with the MPU6050. The MPU6050 uses I2C, and our measurements off the SDA and SCL seems to show that our ATmega328 is able to send information, but that the MPU6050 is not able to send anything back. I have attached schematics of the MPU6050 circuit, the full schematic, the PCB design and datasheet for MPU6050.

The components of the circuit have the following functionalities;

C15 and C17 - Bypass capacitor.

R4 and R5 - pullup resistor for I2C lines.

C16 - Charge pump capacitor.

C18 - Regulator filter capacitor.

Thank you in advance,

Andreas

Hi Andreas,Looking at the schematic of the MPU6050 it looks like the AD0 pin is not tied to 0 volts which would equal I2C slave  base address, or tied to high which would be I2C slave  base address + 1. The data sheet does not state if the AD0 input is internally tied high or low, so this pin my be jumping about on level and the address could be either address.It would be good practice to design for either address with a jumper on the board.

Andreas,Conrad is correct about the AD0 pin. there is nothing I saw in the data sheet to indicate that it's tied high or low internally so you need to connect one way or the other. Then make sure the ATmega is sending the correct address and it should work.

Thank you! I have just revised my design, and I will report back, when the print has arrived.