uart2_tx sends garbage with Jetson TX2; works perfectly with Jetson TX1

Autonomous Machines Jetson & Embedded Systems Jetson TX2
#1

Hello,

we have built a custom carrier-board able to accept a Jetson TX1 or a Jetson TX2. In our design we use uart2 (named /dev/ttyTHS1 in linux) to communicate with a serial peripheral. With a Jetson TX1 module this works perfectly; with a Jetson TX2, we have discovered that uart2_tx sends garbage as soon as we try to emit one character (but not before). We have discovered in the Jetson_TX1_TX2_Interface_Comparaison_and_Migration document that on the TX2, uart2_tx is involved in “strapping” options, which was not the case with the TX1. The same document recommends to check the Jetson TX2 OEM product design guide for details on how that pin should be handled. Unfortunately,
the Jetson TX2 OEM product design guide says nothing about uart2_tx.

Any hint ?

TIA

#2

hello phdm,

FYI, you might refer to Topic 1031828 for strapping option.

#3

I don’find the schemas mentionned in that thread.

#4

hello phdm,

please download [Jetson TX1-TX2 Developer Kit Carrier Board Specification] from Jetson Download Center
thanks

#5

Hi

Just to let you know that the problem was in our hw. We used a TXB0104E (auto-sense bidirectional level translator) and that worked without problem with the Jetson TX1. We have replaced it by a pin-compatible LSF0204 (no auto-sense) and that fixed the problem.on the Jetson TX2.