AM5728: unable to bring up board when camera module gets attached on p16 header

Please expand on 'unable to bring up'.  Have you done all the basic system checks (check all power levels, clocks, resets, etc.)?  Or does the system start booting, but hang at some point.  Please provide more information on the failure.

Dear Robert,

what we analyzed, when we put our

Pcb module over processor headers then power up

the EVM, system starts at some level like

1. Ethernet port led blinks but turn off after 2-3 seconds.

2. LEd lights near sd card does not start to blink.

Any other method to debug this.

Please suggest.

Regards

Krishna Vashistha

I would recommend you start by checking out all power rails.  Make sure the custom board is not impacting the power on the AM57x board.  All power rails should measure their proper voltage without any dip.  Measure the input voltage to the EVM as well, to make sure the overall system is not drawing too much power for the input supply.  Its possible the power rails are normal, but once the processor begins too boot (and requires more power) a power rails fails due to insufficient power.

Dear Robert,

Thank you for the reply.

We have checked all power rails and voltages are ok.

What we observed I want to tell you correctly.

In this conversation I will not discuss about my custom PCB

which I mentioned in previous post.

For the debugging purpose we did following.

1.We have a separate PCB module over p16 header where we can

connect a camera module via hard wiring.

2. We put pcb over p16 header and connect all the 14 bit + sync signals pins of camera.

3. The camera module and the processor board are getting powered by the same power supply which gives 12 volt 4.2A.

4. If Power is on when the camera is already connected to processor then board gets failed to boot.

5. We checked individual data lines where we found that Two data lines Vin3a_d1,Vin3a_d8 may causes an issue because if we press the power button and processor starts to boot then connect  camera's data lines D1 to vin3a_d1 and D8 to vin3a_d8 after board gets boot up (led start to blink near sd card), no issue occurred.

6. If all the data lines(D0-D13) and sync signals are connected and then We powered up the board then board fails to bring up.

7. There is GPIO6_11 for camera enable line. Is there need to use it because we are not interfacing with LCD module (P9 header).

One more thing The same camera module is working(board bring up) on P9 header without any issue.

What causes the problem when we interface with P16 header.

Please suggest

Regards

Krishna Vashistha

The AM5728 device selects its boot mode by sampling the SYSBOOT pins at release of reset.  The SYSBOOT pins are multiplexed with the VIN3A interface which is available on the P16 EVM connector.  Thus - if the camera module is driving those pins at the time reset is released, it could be altering the the value latched by the AM5728 device and thus changing its boot mode.  See the data manual for specifically which pins on the VIN3A interface are multiplexed with SYSBOOT functions.  The AM5728 defines the SYSBOOT to boot mode mapping.

Dear Robert,

Thank you for the explanation.

Now I understood about the exact problem.

One more think which I want to ask.

I saw the AM5728 evm schematics where I found

that an IC SN74HC245N is used to route the VIN3A data lines

on P9 header (LCD module).

To avoid the conflict of sysboot pin over VIN3A lines, that's why It is used or any other reason?

This would solve my entire problem.

Please suggest.

Regards

Krishna Vashistha

Yes - it does solve the issue with latching of the SYSBOOT signals.  It might have also been used for drive strength, as the traces might have gotten long.   So could have been used for multiple reasons.