NHD-7.0CTP-CAPE - BBB does not start up properly

[hendrik]

Hello,
I have trouble with NHD-7.0CTP-CAPEs. I am using them with a beagleboneblack wireless. When I plug in the 5V power supply (3A) to the bbb while it is connected to the display, the display and the bbb power LED start to blink, but the beaglebone won't boot. The problem occurs with any software I tried so far. I have one beaglebone with android 4.2 installed which starts sometimes after some blinks, but this happens randomly and by far not every time I plug it in. Any suggestions why the displays do not work properly?

[Paul_B]

Morning,

I’m sorry to hear about the trouble you are having with the NHD-7.0CTP-CAPE.

It would be helpful to see your boot process. To see the actual boot process a RS232 cable like the TTL-232R-3V3 from FTDI is needed. Just plug it into the J1 connector (located on the BBB) and open a serial terminal of your choice.

Lastly, can you confirm that everything is operational with your beagleboneblack wireless? You wouldn't happen to have a second one available for testing?

Regards,

[Paul_B]

I know this might sound odd but can you please tell me what brand microSD card you are utilizing?

It sounds like an obvious thing to avoid, but sadly, is there any chance you purchased a fake/bad microSD card?

[hendrik]

There is no output during boot process when the cape is attached, since it just shuts down immediately. I tested it with 2 bbbwl on 2 capes. SD cards are xlyne microSD HC class 10 and a sandisk ultra hc class 10, both 16gb, but usually not in use, because I boot from mmc. To me it looks like some start-up overcurrent issue with a shutdown caused by OSD3358 power management chip.
I tried disconnecting the SYS_5V on startup and attached it after boot process. With this configuration the bbb boots properly and the display can be used, but this is obviously way too uncomfortable.

Additionally I tried it with a BBB (non wireless) and everything works fine out of the box.

[Paul_B]

Thank you for the information, can you please let me know which NHD-7.0CTP-CAPE you purchased i.e. L, N, or V?

Are you using the Images available for download in the User Guide or spinning your own overlay?

The NHD-7.0CTP-CAPE was originally designed for the BeagleBone Black (non wireless) back in 2016. I'll try to get my hands on the BBB (wireless) early next week and see if I can replicate the issue you are experiencing.

[Paul_B]

Afternoon Hendrik,

I've completed testing on the NHD-7.0CTP-CAPE utilizing the new BeagleBone Black Wireless and managed to replicate the issue you are experiencing. The issue seems to stem from the OSD3358 power management chip exclusively on the new BeagleBone Black Wireless model.

If you are having this issue, please see the work-around below:

Disclaimer:Modified product will void warranty.

• Cut pins 7 & 8 on connector P1_B
• Solder a 0 Ohm resistor (or solder bridge) between pins 5 & 7

This enables the backlight circuit to run off VDD_5V (main power supply from the DC input jack) instead of SYS_5V (main rail for the regulators on the main board).

[newto]

Hello Hendrik and/or Paul_B

Lucky timing that this question popped up recently, as I have a related one.

Do the wireless functions (wifi and bluetooth) still work with the 24-bit cape installed (and the modifications listed complete)? I've seen a few places that some of the extra pins required for 24 bit over 16 bit colour are also used for wireless addons for earlier beaglebone boards, and I wanted to make sure those features still work with the integrated wireless chip.

[Paul_B]

Hi Newto,

I believe the WiFi/Bluetooth pins were taken from the 10/100 Ethernet pins (don't quote me on that)...

The BeagleBone Black Wireless is still fairly new to me, I'll have to do some additional testing to confirm