I have connected a 4GB Jetson Nano Dev Kit to a Waveshare Power Module (this one, link to waveshare site)
Question 1: Having powered the Waveshare module with its own power supply, do I also need to supply power to Nano?
Surely it works via just Waveshare module but I noticed that when the batteries are 100% charged, the light on the module PSU interchanges green and red indicating that it’s charging one second and isn’t another. The LED on the UPS module indicates batteries discharge thus I assume there is no passthrough of current from UPS hat to Nano (it’s a shame waveshare doesn’t cover such basics of operation in their wiki).
Question 2: Can I power via DC barrely and pins (pins is how UPS module powers nano) as a backup?
I tried putting a jumper on J48 and powering the device via DC, it won’t turn on with pins connected and basically ignores presence of DC input and waits for me to turn on via UPS Hat. Is that normal?
I don’t know about the Waveshare module. Some related comments though:
The carrier board itself is where the Jetson module gets its power. If you’ve powered the carrier board, then you’ve powered the module.
If this really is for power backup (the name “UPS”, or “Uninterruptible Power Supply”, tends to say that this is what it is for), then you would expect that normally the Jetson would use some other power source, but then if the other power source fails, the Jetson would instead be powered by the battery. You will always need power if the Jetson is not fully “off”, but I could see the convenience of having this other power switch on instantly if the main power is lost.
I do not know which LEDs you are referring to. Are you speaking of one on the Waveshare power backup board? Or are you speaking of LEDs on the carrier board the Jetson module mounts on? Just as an experiment, remove the batteries, and see which lights work and when for purely external power. In theory, any LED on your Waveshare UPS (I’m just guessing) might be for (and I have no idea which because I’ve never seen the Waveshare UPS):
Battery power up.
Battery being charged.
Battery providing power (current being drawn).
Most people just have the Jetson on the carrier board, and no UPS. With this smaller form factor there is usually a choice to power one USB connector or via the barrel connector. Sometimes people do supply power via the header pins like I see in the image for the URL you gave of the UPS. Switching between the barrel and the USB connector for power usually requires changing a jumper; the 40-pin header itself has no such requirement. So long as you use the correct voltage, you could simply take the batteries out and try the barrel connector. If that does not work, then I’d assume that the jumper needs to be changed.
I don’t know if you bought everything together, including the Jetson, nor do I know if this is one of Waveshare’s carrier boards (it isn’t a developer kit if it uses a third party carrier board). If this truly is a dev kit, then you can get dev kit information here. You could also get commercial module information here, which is what you’d have if the carrier board is from Waveshare and is not NVIDIA’s. Mostly though you will need to check with Waveshare for the meaning of LEDs if the LED is on either a Waveshare carrier board or a Waveshare UPS; LEDs on the module can be explained on this forum, but I think you’d need to include better information on where the LEDs are that you are asking about, along with what they show when.
I might have provided some unreliable info in the initial post. But your comment led me to discover this.
Here is what I observe, the setup still doesn’t perform as expected with respect to backup power provision:
I set the J48 jumper to accept power from DC barrel. I disconnect the PINs connection to Power UPS module.
I plug in the barrel that feeds 5v 4a - nano starts up as expected. Good.
I disconnect the DC barrel from nano, return PINs connection.
Putting a power switch on the UPS module to ON position surely starts up the device. Then I shut it down.
Keeping the UPS switch in OFF but PINs connected to nano, I put in the DC barrel into Nano. It starts up.
I turn on the UPS - it keeps going. LCD screen on the UPS lights up and shows no power draw.
I disconnect power from the DC barrel. No power connected to UPS, just batteries. Nano turns off. So it seems like there is no handoff of power source in nano. If it started via pins, it goes on via pins, and the only way to achieve backup power is to keep the UPS unit connected to an outlet via it’s own adapter.
Summary for anyone looking for similar info: waveshare UPS hat works well when it’s the only power source going into nano.
I don’t know what the “PINs connection to Power UPS module” is, so it is rather difficult to reply on it. Some more comments though.
Power on Jetsons must be very stable. Almost any power fluctuation will cause a shutdown or reboot. The power to barrel jack versus from USB is what the jumper changes. I don’t think the power to the 40-pin header (is this what you mean by PINS?) will change based on the barrel-versus-usb-power jumper. However, if the voltage provided before and after switching supply source is too far off, then I think this will fail.
Just guessing, I’d say if that if the power from the barrel is slightly higher voltage (but stable) versus the UPS, then switching from barrel to UPS would cause a failure, e.g., a shutdown or reboot. The power load the Jetson is under at the moment would probably also change requirements from the UPS, and this same condition of stability when switching between the two sources would still need to be met, but would become more difficult.
Is power always supplied by the UPS? If running only on the UPS, what voltage range is seen (this would be interesting to know down to about 0.01 V or higher resolution, measured from the header). Similarly, what is the voltage range at the header with only barrel jack power, and going between higher loads and lower loads? More importantly, what is the difference in provided voltage under all conditions? This won’t solve the problem, but knowing if this is stable says whether it is possible to succeed.
Most UPS with battery would run on battery at all times, and recharge simultaneously so the battery never goes down so long as there is power. Maybe this is designed to only run on battery, and not work as a failover? I don’t know anything about the product. If power is continuously supplied by the battery, but input from outside power is to the barrel jack without the battery being able to recharge on this, then the battery would be discharged far too fast. I just don’t know the design of how this is supposed to work. I’m guessing you are going to need Waveshare tech support to get an answer since they are the only ones that know what is going on inside.