I have managed to blow up 2, maybe 3 (one went missing but I think it had the same problem) specifically they no longer show up on the I2C bus.
To be clear the signals on both pins SCL and SDA look perfect on the scope still directly on the Teensy pins at the board board and on the audio board at the pin inputs. I
I am using a level shifter using BSS138 to isolate the 2.8 volt chip sharing the buss with the audio board. The 2.8v side had 470 pull ups because of very slow rise times. I may have found that issue and before the next board arrives anyone know if that would cause the codec to blow its I2C inputs.
I will try some larger pull up resistors on the 2.8v side maybe 4.7k and check the rise times I guess and just use the 2.2k already on the 3.3v side.
I I most likely goofed up and just plugged the teensy in backward or something that got them but $60 gone I thought I might be missing something.
To be clear the signals on both pins SCL and SDA look perfect on the scope still directly on the Teensy pins at the board board and on the audio board at the pin inputs. I
I am using a level shifter using BSS138 to isolate the 2.8 volt chip sharing the buss with the audio board. The 2.8v side had 470 pull ups because of very slow rise times. I may have found that issue and before the next board arrives anyone know if that would cause the codec to blow its I2C inputs.
I will try some larger pull up resistors on the 2.8v side maybe 4.7k and check the rise times I guess and just use the 2.2k already on the 3.3v side.
I I most likely goofed up and just plugged the teensy in backward or something that got them but $60 gone I thought I might be missing something.