You need to get all the power out of your Jetson Nano Developer Kit. Looky here:
There are three ways to get power in to the NVIDIA Jetson Nano Developer Kit. The simplest is to supply 2 Amps at 5 Volt to the micro-USB connector. The hardest is to supply power through the GPIO Header. The GPIO Header has two 5V pins, each can accept up to 3 Amps. This gives 6 Amps total.
We cover the third possibility here. Supply 4 Amps at 5 Volts through the Barrel Jack connector. That’s what the cool kids do, you should too!
Why not Micro USB
There are times when you’ll may want to run your Jetson Nano through micro-USB. It’s pretty convenient; all you need is a cable and phone charger wall wart that you have laying around (make sure it’s 2 Amp). But here’s the thing …
The Jetson Nano module runs in 10 Watt mode by default. Quick math tells us that is 2A @ 5V. Sounds like everything’s good, right? Nope. That’s only for the Nano module, not the full board and attached peripherals. By the time you add on a keyboard, mouse, cameras and all the good stuffs, you’re over that. The Nano doesn’t like that so it turns itself off, similar to a circuit breaker when you draw too much current in your house.
Note: When running from the micro-USB connector, you should probably be running in 5V mode. See the ‘Notes’ section below on how to do that if you must.
What to Do?
Use the Barrel Jack Connector! You can supply 4A @ 5V, which should be plenty for most projects.
You will need two things. First, a power supply. In the video, we use a Adafruit 4A @ 5V power supply. The connector on the power supply is 5.5mm outer diameter (OD) x 2.1 mm inner diameter (ID) x 9.5mm length. This can be pretty easily confused with a 5.5mm OD x 2.5 mm ID, so make sure you get the right one.
You will also need a jumper pin. These are the standard 2.54mm hobbyist style. Also, you will also need an extra jumper pin if you plan to flash the Nano with NVIDIA SDK Manager, so at least get a couple. In the video, we use a bag of color jumpers. You may be able to get along with a bunch of black ones if you are soul less. SparkFun sells onesies if you just want to buy a couple.
You need to place one of the jumpers on J48. J48 is located between the Barrel Jack connector and the Camera connector. This jumper tells the Nano to use the Barrel Jack instead of the micro-USB port. Then plug the power supply into the Barrel Jack, and the Nano boots. No fuss, no muss.
In the video, we label the power supply transformer, and add color electrical tape to the barrel jack to distinguish them from other, similar devices. You’ll find this is pretty common when you get out to places where people make their living do such things.
The reason people do this is that even though all the transformers and power supplies look similar (in fact the jacks can be the same size), the transformers may supply different voltages. For example, both the Jetson Nano and the Jetson TX2 share the same connector size, but the Jetson TX2 uses 19 volts, and the Nano uses only 5 volts. If you plug the TX2 power supply into the Nano, all the magic smoke will leave and you will be sad. And people ask why I have a fire extinguisher in the videos!
The Jetson has two power profiles, called modes. Mode 0 is 10W, Mode 1 is 5W. To set the mode to 5 Watt mode:
$ sudo nvpmodel -m 1
To set it back to 10 Watt mode:
$ sudo nvpmodel -m 0
The default image on the Jetson Nano is in 10 Watt mode. There’s another utility name jetson_clocks with which you may want to come familiar. Here’s a video which explains power management, modes and jetson_clocks in slightly more detail. Looky here: