discovery which was inserted into Frankenso 0.4 inside a case under the hood in a warm garage has died (this one now has "1" drawn on it): a bunch of system LEDs blink randomly as if there is a power issue. Took another discovery which was in the garage as well and somehow 10 minutes later this one would not recognize ST-LINK as USB device while rusEfi seemed to be running fine (this one has "2" drawn on it).
Some new content.
Healthy board, diagnostics step 1:
This one says "1" in black sharpie close to the ST logo. This one lights up four LEDs with mini USB and without JP1, same board with JP1 has zero LEDs emitting light. Next step?
This one says "2" close to the ST logo. This one blinks LD1 off/red/off/red without JP1. With JP1, it looks like rusEfi firmware is running but this board is not recognized as ST LINK usb device. Next step?
Note to myself: do not take pictures of black cables on black desk.
Would I be correct that you are using a laptop, the power cord probably has 2 wires with no ground? I suspect a GND loop issue.
I'm not quite sure what could be wrong with board 1, I would wager a guess it's USB power supply related. If powered via Frankenso and not USB, does it preform the same, AKA solid power supply vs USB power supply. I suspect the LD3985M33R is being overloaded and is short cycling. This can happen with a mild over current situation. If you have a hard dead short to GND, you have been blowing some combination D1 to D3. However if you have a slight over current, it allows the LD3985M33R to kick in the thermal limits, turns off, cools down turns on, over heats, etc which results in the blink power to the F4 and blinking 3V supply. I would bet that chip is getting hot when this is happening and if you gave it time, it would blink at a slower rate as it heats up the surrounding PCB. Don't touch the LD3985M33R you'll likely say ouch. What I don't know is what on the F4 is shorting to GND. Could be lots of things. Connecting to the board to the Frankenso power supply will likely burn what ever is causing a problem. With some luck it will be the audio codec chip or some other thing we don't care about. If it burns the F4, then it was broken any how. I might guess ESD for this, but could also be a GND loop issue with the USB cable.
Per board 2, this does seem odd. We know dead shorts to GND will blow D1 to D3 in various ways. In your case those all work, so the issue probably wasn't related to over current. Which leads me to think over voltage. The chances of a voltage surge coming from the Miata, past the F4 and breaking the STLink is not very likely, so I'm more inclined to think the surge came from the USB connector, or perhaps from a human ESD. I find it odd that LD1 is off while LD2 is bright. LD1 is a multi-color LED, connected to 3V , which we know is OK as it's powering LD2. The STLink can make that red, green, or 50/50 red green. However under no situations should that LD1 be off when you have 3V. So this LD1 must be broken, which I can only see happening via a voltage surge. The surge that took out the STLink probably is also what took out the LD1. I would most likely point a finger at the USB connection, as you may have GNDed your car via USB cable. I doubt a human ESD as I don't expect you could take out 2 chips in one event. You body just doesn't store enough energy.
If it's a USB GND issue, you might want to GND your shield before connecting the USB cable. This will allow the PC and vehicle to equalize before the 5V and data connections are made.
I have seen a number of similar issues with grounds on the CANBus, laptop power supplies can cause big problems when they are plugged into the mains supply and running a ground wire between the laptop and the ECU is highly recommended, if you can then always run the laptop from its internal battery. One very well known vehicle manufacturer blew up a lot of ECUs by not using a ground wire of the CANBus of their diagnostic equipment.
The USB cable should ground the two devices through its screen, you could check that that is properly connected.
On board 1, for some reason I thought you said that the red green were blinking, sorry my bad. Those being on solid would appear to indicate the F4 is shorting a pin to GND which is holding the LED's on. I'm reasonably sure that F4 is toasted, probably it's ESD diodes. Can you connect your meter in series with the USB power and measure the current some how? Do you still have that hacked USB cable? You don't need it for USB coms just to get that 5V to power it. The current draw would help shed some light about what is happening. Perhaps you could jumper LDD with the meter instead of a jumper and see how much power the F4 is consuming. I seem to recall the 3v regulator could only produce around 100mA to 150mA. Also connecting board 1 to frankenso power supply would likely burn off what ever is broken, and make it really obvious what's wrong.
On board 2, can you measure voltages from each of the 3 pins of LD1 referenced to the GND pins in the corner of the PCB. That will help show what the STLink chip is doing. I'm pretty sure that chip is simply toast and probably. I'm not sure how esle to test the STLink chip. Board 2 can probably be programmed via different STLink and you can probably still use the F4 part of it.
I feel reasonably confident that each board has a broken large black chip. It's not like prior failure where you can swap D1 for D3 and revive it. I think the major chips are toast, and the board is probably not salvageable. What I wonder is why it happened.
I believe that with the Franekenso boards, Discovery failures have been relatively few. Is that correct? I wonder if there could be some issue with the Frank boards. I don't know of any, but perhaps there could be.
kb1gtt wrote:I believe that with the Franekenso boards, Discovery failures have been relatively few. Is that correct? I wonder if there could be some issue with the Frank boards. I don't know of any, but perhaps there could be.
True, few discovery failures while on Frankenso board. I can recall the mystery of @s board killing discovery unites one by one.
With #1 board I am not 100% sure but it could be that the laptop was not even connected, just long USB cables from headlight area where the ECU was into inside the cabin, and cranking.
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