Using the auto power on feature with the NVIDIA Jetson TX2 development kit

There has been a discussion about enabling the auto power on feature of the Jetson TX2 development kit on devtalk.nvidia.com. The solutions discussed there involved using a additional micro controller or soldering directly on the quite expensive board which is not desired by quite some users. This article will show a fairly simple and quite safe method to use the auto power on feature without additional circuitry or soldering directly on the board.

According to the Developer Kit Carrier Board Specification the auto power on feature can be enabled by shorting the CHARGR_PRSNT pin (pin 1) of the charge Charge Control Receptacle (J27) to ground (pin 5). This is fairly hard to achieve without having the appropriate connector or soldering the board itself. Since the pins 2-4 also are input pins it is safe to short all these pins (1-4)  to ground. This can easily be achieved by using a small piece of a copper plated circuit board matching the receptacles dimensions.

The piece of circuit board has to be cut and grinded to proper dimensions. A board of approximately 6mm x 8mm x1 mm size is fine. Afterwards the copper plating has to be grinded off in the area that can get contact with any other pin than the five mentioned pins. It is advisable to check this with a Multimeter while moving the board left and right in the receptable before attaching power. If you damage your board due to this procedure, you are the only one responsible. The resulting board is being shown below.

The circuit board.

The completed circuit board.

This board turned out to be a bit to thin to ensure contact, thus a bit of soldering tin has been applied to the copper plating to ensure the contact between the pins. The tiny board can now be inserted into the Charge Control Receptacle

Jetson TX2 with auto-power-on

Jetson TX2 Development board with applied board for auto-power-on

With the crafted piece of circuit board inserted into the Charge Control Receptacle the Jetson TX2 now boots directly after applying power. This has been tested with two different development boardw. For the older board (Revision B04, SATA port facing up) it worked, but it did not work for the newer (Revision C02, SATA port facing to the side) one. So your mileage might vary.

Jürgen

References:
1 NVIDIA development forums
2 JetsonTX1 TX2 Developer Kit Carrier Board Specification p. 31
3 how-to-find-carrier-board-version

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