TPS929240-Q1: The TPS doesn't answer any of the read commands that worked with the 16 channel version

Hi Simon,

There are a number of factors that could be causing this. First, I'd like you to confirm that the DEV_ADDR byte in your UART frame matches the device address set according to ADDR2, ADDR1, and ADDR0 pins. The 24 channel device has three address pins while the 16 channel device has four so I suspect that if you are trying to use the same code you may be addressing a device that is no longer present on the bus. 

Thanks,

Jaron

Hello, 

Thank you for your answer. We are using the external adressing method so we connected ADDR2, ADDR1 and ADDR0 to the GND. We are using 00h in the DEVICE_ADDR used in the byte. Could it be something else ?

Hi Simon, 

And to confirm is there only 1 device on the bus? Or if there is more than 1, they are all uniquely addressed? Can you probe the RX and TX nodes and confirm that you are seeing the waveforms you expect on RX?

Thanks,

Jaron

Yes only one device on the bus. While probing, the RX waves were as expected. It's worth mentionning we tried switching with another TPS in case of a problem with the component but we have the same problem.

Simon

Okay thanks for checking that. What about details of the board? Are you using the same board you used with the 24 channel device but with a 16 channel device populated in place of it? Although they are the same package they do not have identical pinout. 

Jaron

The board is a different one, adapted for a 24 channel TPS (or it should be). Supply and VBAT are provided with a 10V Buck regulator as well as FS0. We are only using 15 channels (the goal is to prove the solution can work with any number of channel) so 9 channels are left unconnected. RX and TX have a 47k pullup resistor connected to VLDO.

If I can provide any other information please tell me.

Simon