Hi there,
We have had many OpenMV H7 Plus cameras fail and we cannot seem to think of a reason so I thought we would ask here
The cameras are used in a robot and are connected to 5v via the VIN pin from a Pololu DRV24 5v 5a Step Down DC-DC switching regulator
We have added 100nf and 100uf capacitors to smooth any switching noise too.
The cameras are used to transmit UART to an Arduino mega pro embed. We only connected TX of camera to RX of hardware serial 2 on the Arduino. We did not connected the RX of the camera to anything or use any other digital I/O. We connect the camera occasionally from USB and upload a script on then disconnect. They werent used for a long time maybe 3 to 4 hours then shut off for a day or 2. Please help us figure this out as we have killed many cameras and it is becoming expensive.
Thanks for your time
Hi, the H7 Plus will not normally die from 5V on VIN. What else are you doing with the system?
Are there are components on the board that have gotten very hot? Any components that have exploded?
It’s the CPU / 3v3 regulator area that heats up even if I power from USB only. And no other digital IO is connected to it. It only runs a script that searches for 2 colours and transmits there location over UART to the Arduino.
The other 2 have died from the same connection but were connected to each other via UART as well. We used UART 1 to connect the cameras together
And UART3 to connect to the Arduino via CAMTX-> ARDUINORX only
They are no longer detected over usb or even light up
Could you send me pictures of the front and back of the board? I want to make sure its an official version. There are clones with different circuits out there.
They are official as I bought them from the OpenMV store about 6 months ago.
Can you send me pics of the wiring of the boards? The last time we had complaints about this, the customer’s wiring was shorting to components on the board, and they had accidentally let 5V touch the 3.3V rail.
Here’s a pic of the wiring. It’s done by a PCB HAT I made and got done at JLCPCB that sockets into the camera so no wiring to short out.
Hi Yshaalan,
That seems correct, do you have a shared ground with the Arduino Mega? Also, can you verify the voltage on the TX pin attached to the Mega when the camera is idle and not doing anything.
I’m wondering if there’s some type of weird issue with a floating ground connection causing a voltage higher than 5V appearing on the GPIO pin and causing back feeding into the H7 Pluses voltage rail causing chip failure over time.
Yes, the grounds of both are common and I verified without the camera connected, the Arduino has about 2.25v on that pin.
Oh and side notes, I got most of the cameras that failed this way to get working again by supplying 3.3v from the 3v3 pin. The 5v regulator still heats up a bit after a long time but the cameras operated otherwise normally
Mmm, that would be a failure of the 5V to 3.3V regulator. This is not normal unless you were applying more than 5V as the same regulator works with USB 5V.
I wasn’t, because the regulator is a fixed LDO and none of the other components being powered by the 5v Rail (Time of Flight sensors) were harmed.
Hi Yshaalan,
I don’t know what the error could be. The circuit you have is correct. As mentioned, the same regulator is subjected to 5V USB and doesn’t fail. So, it failing from 5V VIN means there’s something wrong with the VIN.
If you applied 3.3V to the camera while applying 5V VIN or USB at the same time… this would have damaged the regulator.
I haven’t done that cuz the original PCB only has the 5v pin wired, I had to jumper it to make the 3.3v connection after my boards started dying
I’m not sure what the error is. If they don’t die when applied via a 5V USB bus but then die with the 5V from VIN… there has to be an issue with the VIN source. The same regulator handles both inputs.
You can use an oscilloscope to observe the voltage waveform on the VIN-GND pin for a long time. Check if there are excessive ripples. I remember that the input voltage rating of this BUCK chip is only 5.5V. If the 24V to 5V module has poor performance, the peak voltage may exceed 5.5V, which could potentially damage the BUCK chip over a long period of use.
