AMB82-Mini Power Supply

Technical Discussion AMB82-mini
1

Hello,

I connect the AMB82-mini to my computer thru the USB port and it works fine.

I need to use it even when its not connected to my computer.

Do i apply +5V to the V_USB pin to power it?

I tried that and it didn’t seem to power up properly, the red light comes on, but after that it does nothing, the program doesnt seem to start.

Seems if its not powered thru the USB connector it doesnt power up properly.

What is the proper way to power it without using the USB connector?

Thanks

2

Hi @nsmith1024,

Have you connected the GND pin to GND too?

It has been verified that connecting 5V to Vusb and GND to GND works.

Thanks.

3

Hi @nsmith1024
To power the AMB82-mini without using the USB connector, you should apply a stable 5V supply directly to the VCC pin. Ensure the ground is connected properly. The red light indicates power, but the board might need proper voltage levels and stable power to function correctly. Double-check the voltage and connections to ensure they match the board’s specifications.

4

Hello,

Please see the attached image published on your website of your board layout of AMB82-Mini.

Please tell me how to power the board without the USB cable.

One answer above says to connect 5V to V_USB, another says connect to VCC.

See attached image of the layout, there is no VCC pin, there is only GND, V_USB, VDD33.

So it seems I should apply 5V to V_USB, and then that will output VDD3.3.

When i apply 5V to V_USB the red light comes on but the board DOES NOT boot up, the red light just blinks.

The board doesnt boot up unless its connected using the USB cable.

I tried CHIP_EN both at 3.3V and ground, neither one works.

Please tell me how to power the board without the USB cable

Thanks, have a nice day.

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5

Hi @nsmith1024,

You are right, 5V is required to power up the board and V_USB is the correct pin.

You may connect V_USB to a stable 5V DC power source and GND to the ground to power up the board without using USB cable.

Thank you.

6

I did that, the red light comes on but the board does NOT boot up.

Something is wrong when using the V_USB to power the board, what about the chip_en? is that needed?

Thanks

7

Do you have a data-only USB cable or a way to read the serial output via UART while the board is plugged in via the V_USB pin (basically a way that doesn’t potentially backfeed 5V into your computer via the USB line)? If so, could you dump the logs for that here? I think that would help with diagnosing the problem.

I’m not connected to Realtek or the Ameba teams, but we’ve been developing for the AMB82-Mini for a while now. One of the things we found early on is that the dev board isn’t equipped to handle unstable or noisy power supplies like the Arduino and ESP32 boards are. We discovered this by reading the UART while connected to the power supplies we were testing and discovered that our boards were either boot looping or rebooting at some specific point in our program.

Basically, our findings boiled down to this:

  1. Power supply with very fast transient load response is required. This was the number 1 cause of power supply-related boot loops and board crashes for us. If the AMB82-Mini suddenly switches to some high-powered task, like doing object detection and streaming video over Wi-Fi simultaneously, and your power supply isn’t equipped to handle the sudden increase in demand while staying within the board’s voltage requirements, it reboots. This also ruled out a lot of the more cost-effective linear regulator-based power supplies for us.
  2. Power supply must have low output noise. If the power supply output is noisy, weird things happen. We saw image artifacts (green lines) from the camera output and unstable Wi-Fi on noisy power supplies.
  3. Power supply must not resonate with dev board’s buck converter. This is a weird edge case. The AMB82-Mini uses 2 MT8102NSBR buck converters operating at 2.5MHz to produce VDD33 and VDD_DDR. If your power supply happens to resonate with it, you’ll see similar effects as the second point even if nothing seems to be wrong when scoping into V_USB. We also experienced random reboots into download mode that might be related to this.

If you determine that the issue with powering your board via V_USB is related to a power supply mismatch, we found great success using the MP1584 switching regulator. It operates at 1.5MHz, so it can respond very quickly to sudden load demand spikes and it doesn’t resonate with the MT8102.

8

Hello at_and_red,

Thanks so much for the message, i really appreciate it.

I will investigate what you said and post the results.

Thanks

1 Like
9

I have same problem for year ago. I fix this by use voltage supervisor with delay to monitor VDD33 and connect reset output to CHIP_EN

10

To power the AMB82-mini without a USB connection, you should apply 3.3V to the VCC pin, not the V_USB pin. The red light indicates that the device receives power, but if the program doesn’t start, it suggests the VCC pin isn’t properly powered. Ensure you’re providing a stable 3.3V to the VCC pin for correct operation.

11

Hi, ive been facing a similar issue, however if I hook up the AMB82 mini to my power bank with the microUSB cable, it works perfectly fine.

What I believe is that current supply is the issue as the current rating on the Li based power bank is higher then General purpose 9V battery.

I will try hooking it up to a Li battery next and hopefully get it to work.