StonedEdge
Posts: 54
Joined: Wed Oct 28, 2020 11:42 am

Re: Retro Lite CM4: Handheld Gaming Console

Wed Jun 09, 2021 7:27 am

Just a quick question - is the WiFi module transferable from CM4 to CM4? I ordered the wrong CM4 (non-WiFi) and have another CM4 lying around with a WiFi module (dead) that I'd like to transfer it to.

StonedEdge
Posts: 54
Joined: Wed Oct 28, 2020 11:42 am

Re: Retro Lite CM4: Handheld Gaming Console

Wed Jun 09, 2021 3:41 pm

Also - I am still having trouble getting my CM4 to boot. I'd like to finish this project as soon as I can, so I'd really appreciate if anyone would take the time to look at my schematics & board files to see where I'm going wrong.

I've made it up to Step 10 of the "A. Troubleshooting Section" = nACT_LED does nothing. I can't see anything wrong with my SD lines or traces. I've flashed the latest version of RetroPie onto my SD card using balenaEtcher and also the Official Raspberry Pi flashing tool. Does anyone notice anything in particular with the pinouts, schematics or footprints of the CM4? Maybe someone might be able to help me not throw in the towel for this project...

I've attached the schematics in PDF and board/sch files for EAGLE.
I'd really appreciate it if anyone could take a look! Really getting sick of debugging...

Thanks everyone.

PDF Schematic
https://drive.google.com/file/d/1zJb33g ... sp=sharing

Eagle BRD File
https://drive.google.com/file/d/13-FxUa ... sp=sharing

Eagle SCH FIle
https://drive.google.com/file/d/11BpjzE ... sp=sharing

Flavor
Posts: 5
Joined: Fri Jun 02, 2017 5:38 pm

Re: Retro Lite CM4: Handheld Gaming Console

Wed Jun 09, 2021 5:45 pm

We gave it a quick look. Here are some notes about stuff that could cause it to not boot.
Screen Shot 2021-06-09 at 11.39.58 AM.jpeg
Screen Shot 2021-06-09 at 11.39.58 AM.jpeg (141.56 KiB) Viewed 254 times

StonedEdge
Posts: 54
Joined: Wed Oct 28, 2020 11:42 am

Re: Retro Lite CM4: Handheld Gaming Console

Thu Jun 10, 2021 3:56 am

Flavor wrote:
Wed Jun 09, 2021 5:45 pm
We gave it a quick look. Here are some notes about stuff that could cause it to not boot.

Screen Shot 2021-06-09 at 11.39.58 AM.jpeg
Hi, thanks for your reply back.

As mentioned above I have checked all of the voltages on all pins required for boot (RUN_PG, GLOBAL_EN etc... I measure 3.3v and 4.93v on those pins). All voltage rails rise to 3.29v and 1.78v, which shows that the internal PMIC is doing its job. I measure a solid 5V on the Pi input pins. The SoC heats up.

You make a good point regarding the ATtiny. Am I correct in assuming that the CM4 will not boot if power is applied to any pin before 5v is applied? I may have not set pins 3 and 5 on the ATtiny to inputs in my code, rather they may be currently floating. GPIO16_VOLTAGE_SHUTDOWN sends a GPIO high to the ATtiny to be read as input to shut down system when voltage of batteries reaches 3.3v and GPIO25_PI_SHUTDOWN_INIT drives a GPIO low on the Pi to shut down the operating system safely. If these pins are high, would this prevent boot/potentially killed GPIO banks if they go above 3.3v?

The other issues that I thought of:

1) SD lines are too long/wrong pinout - unlikely as the SD is a super slow bus at like 100Mhz
2) Pinout for CM4 is wrong entirely :P
3) I’m back feeding the CM4 with 3v3 regulator somewhere
4) Capacitance on 5V lines isn’t enough, causing instability issues. Increase output caps to be 15v-26v tolerant. As ceramic caps need to be rated well over the actual bias voltage since they derate so much, use higher voltage rated caps. Not enough output capacitance is making it difficult for the regulator to supply transient loads. The Pi switches on and off quickly, so it needs a big charge reservoir in the form of both bulk caps at the input and decoupling caps at power supply pins (right now I'm using small 0603 10V 1.0uF caps x 3 for the output, 0603 10V 1.0uF cap x 1 for the input).
5) GPIO pins from attiny causing issues (high before power up)
6) I screwed up the nACT_LED - pulled it low to GND instead of high to 3.3v. I have fixed this by soldering one end of a resistor now to 3v3 (still no activity on the green LED at all - no flashing or no signs of life. LED is not dead as checked with multimeter)

StonedEdge
Posts: 54
Joined: Wed Oct 28, 2020 11:42 am

Re: Retro Lite CM4: Handheld Gaming Console

Fri Jun 11, 2021 1:10 am

Update - I do get a flash on the ACT led now (only a single flash followed by solid green...)

Flavor
Posts: 5
Joined: Fri Jun 02, 2017 5:38 pm

Re: Retro Lite CM4: Handheld Gaming Console

Fri Jun 11, 2021 4:01 pm

The CM4 has a bootloader screen that should come up even if SD isn't working or whatever.

I might focus on trying to get that screen up and not worry about the SD card stuff at the moment.

You are using the LITE module, right?

Return to “Compute Module”