Tx2i Custom Carrier Design questions

Hello Nvidia !

I have designed a Tx2i custom carrier board in order to provide 4 GbEth link via a managed switch.
I have read the TX2i design guide, and i still have some troubles to auto boot my tx2i.

The design guide says:

"
The TX2i PMIC has a level sensitive on input, so in order to power automatically when the main power is applied (Auto-Power-On), all that is required is for the POWER_BTN# pin to be pulled up. Since this pin is pulled up on the module, it can be left unconnected for Auto-Power-On to be supported.
"

So, like a fool, i have just connected the main supply to the module. (i also have a 0R resistor to GND on CHARGER_PRSNT#, which seems to be the way to go to also support Tx2 modules). These are the only pin connected, all the others are floating.

But, when 12V main power is applied, i have no lifesign on UART0. Input current is @135mA during ~10s, then fall to 120mA.

I am aware about the strapping options, anyway all my level translators are disabled (HiZ).

Unfortunately, i don’t have any Jetson Eval board supporting a tx2i module. I only have a Tx1 developer kit. So i can’t test it outside my board.

My questions are :

  • Is VIN_PWR_BAD# needed in my case ? (pullup on tx2i module)
  • Dumb question, but did my brand new tx2i module came with a working system ? (Uboot a least)
  • do you have any hint or idea to help me ? :) Maybe i missed some design instructions. It is not very clear what you need/don’t need when you have to support autoboot.

Just for background, last year i have successfully designed a tx1 custom carrier board, with no big problems beside boot strapping. The Tx2i seemed to be the easy one regarding autoboot…

Thank you in advance,

Thomas.

HI thomas.fourcroy,

The section on Auto-Power-On intended for designs supporting either TX2/TX2 or TX2i does say that you just need to connect CHARGER_PRSNT# to GND and leave POWER_BTN# floating (pulled up on module). This does assume that your design is similar to our carrier board, at least in the way the power handshaking signals are handled. The Jetson TX2/TX2i OEM DG includes a power sequence for the Auto-Power-On case which does show VIN_PWR_BAD# going high before the module powers on. The signal goes to a few places on the module. It is “OR’d” with the reset ouput from the PMIC, so if it is low, it holds the module in reset. It also is OR’d with other signals going to the EN0 pin of the PMIC which is used to power on/off the module. Again, if it is held low, the module should power off (or remain off). I don’t know if it is OK to just let the module pull-up (pulled to module 5V supply) handle VIN_PWR_BAD#. In our carrier board design, it appears we have a circuit to keep it low for a period after main power is applied (see far right/bottom of figure below power sequence). According to the pin description in the OEM DG, this is to keep the system from trying to power-up before the main power supply is stable.

I assume so, but that is out of my area of expertise. Have you tried to flash an image on the system? Have you tried going into Force Recovery mode? That would at least show you whether the system appears as a USB device.

Thanks