Two BBBs have broken down, is there any mistake in my circuit board?

Hi guys,

I run 12V valves(insulated channels) and read pressure values by I2C with my BBB board. I don’t understand what has happened but two BBB were broke down with this board.

When i am plugging in my power supply; one of the broken BBB’s LED is not work, the other one’s LED is on but does not open.

I wonder if is there any mistake(shortage) in my board?

There are the board’s layout and schematic;
https://www.dropbox.com/s/tu3go2uei8ikryp/valf_layout.pdf
https://www.dropbox.com/s/dpziyloas6bttpl/Valf_schematic.PDF

Thanks for your help in advance.

Regards,
Ugur

I see lots of issues. Can you show what you have connected to what on your headers?

Your 3.3V and 5V rails are on all the time. I suggest you take a look at the SRM to see how to handle the power. The 3.3V cannot come up before the processor comes up. You are violating that rule. http://www.elinux.org/Beagleboard:BeagleBoneBlack#Expansion_Header_Usage

Any reason your grounds are not tied together?

What voltage do you have coming into the AIN4 and AIN6 signals?

Gerald

Hi,

Thank you for your reply.

Headers;
J1-J2-J3-J4-J5-J6-J7-J8-J18-J19-J20 / headers of valves,
J17 / header of pump,
J12-J13 / headers of digital input,
J9-J10 / headers of 12 volt and ground,
J14 / header of analog input.

Grounds are not tied together because high current switch is occur in our valve circuit. We separate 12 volt’s ground and 5 V’s ground.

AIN4 and AIN6 pins voltage comes from analog sensor. They are certainly less than 1.8 volt.

Could i use a load switch to solve the problem (The 3.3V cannot come up before the processor comes up) ?
And is there any problem to give voltage(5 Volt) to P9_5 and P9_6 while it’s turned off?

Thanks,
Ugur

Just follow the link I sent. Do what ir says in whatever manner you choose. If you put 5V into P9-5 and P9-6, the board will be powered on, unless you press the power button causing it to power back down.

Gerald

Hi,

OK i solved the 3.3V problem with a load switch, thanks again.

One more thing, i put the BBB inside a box and need to check the power led without open the box. So i’m trying to move the BBB’s power led outside of the box.

I find the pins of user leds in the BBB_SRM;

USR0 → GPIO1_21
USR1 → GPIO1_22
USR2 → GPIO1_23
USR3 → GPIO1_24

But I didn’t find the GPIO pins in Expansion Header of P9 pinout and P8 pinout. Is there any additional source which can i look?

Thanks,
Ugur

These GPIO pins are dedicated to the LEDS. They do not go to the expansion headers.

Gerald

These GPIO pins are dedicated to the LEDS. They do not go to the expansion headers.

Gerald

You could move the USR0…3 functions to other GPIO on the expansion headers by modifying the device tree. Look at arch/arm/boot/dts/am335x-bone-common.dtsi

Regards,
John

I solved the problem (3.3 volt and some voltage values are coming to beagle pins before the processor comes up) with a load switch. Its enable voltage comes from the SYS_RESETn.

https://www.dropbox.com/s/7hocodvoeib2q76/valve_drive.pdf

After install the switch load on my board, the 3.3 volt is not applying I/O pins before the SYS_RESETn signal is HI.

Thanks,
Ugur