Wonky COM Port: Potential hardware issue?

[vizier87]

Hi everyone. I have a feeling that this might be more of a hardware than software issue but here goes.

I built a custom board for a chip which has Arduino support (based on CT_ARM: here CT-ARM User's Manual - Google Docs

They released the design online so I ordered the PCB later based on it. It looks exactly the same with the board I have. Cytron has dicontinued the board.

It's a Nuvoton chip, NUC131L2DAE.

Now, the program I developed for it took me 2 years and let's say I just couldn't bear writing new code for it. So I wanted to stick to the Arduino code rather than using their IDE (it's called KAEL).

Now, I've been able to load the code via ICSP from a working Nuvoton chip of the same model into the new board I built using their bootloader called NuLink. I loaded a simple "ADC to Serial" program, and I could read the serial port perfectly well from the newly built board.

However, I couldn't PROGRAM the board from the COM Port. Here's the error:

Sketch uses 4328 bytes (6%) of program storage space. Maximum is 65536 bytes.
Global variables use 80 bytes (0%) of dynamic memory, leaving 8112 bytes for local variables. Maximum is 8192 bytes.
error: Failed to open COM9
Failed uploading: uploading error: exit status 0xffffffff

Now, here's the strange thing. I've changed the FTDI chip twice, still getting the same issues. But I COULD read the serial port's ADC from the pin A0. (works well too!).

And sometimes, some strange thing happens when I plug in the chip. My mouse would stop working for a while, and some wonky things happen on my screen like right-clicks occurring around my desktop without me clicking.

So I'm thinking it's definitely hardware, but I couldn't determine which.

The COM Port is detected in the Device Manager, yes. But when I try to load a simple blinking code, it says "Failed to open COM9". Changing the COM Port number didn't help too.

Anyone?

Thanks!
Vizier87

[rsmls]

@vizier87

So I'm thinking it's definitely hardware, but I couldn't determine which.

Possibly. And without knowing the details of the hardware you've built, I wouldn't know where to start either. So maybe start with sharing some details; schematic + PCB layout.

@vizier87

But I COULD read the serial port's ADC from the pin A0.

Does the serial port have an ADC? Sounds odd to me.
Anyway, I can see how you could read/receive from UART and not send/program to it if the problem is isolated either one of the UART data lines. I assume you've double-checked the connections in your schematic, the PCB design as well as the project as built, and have verified with a continuity tester that all nets trace to the ARM chip the way you designed it.

@vizier87

(it's called KAEL).

KEIL probably. It's one of the main commercial/pro IDE's out there.

[jacksmith16]

@vizier87

Hi everyone. I have a feeling that this might be more of a hardware than software issue but here goes.

I built a custom board for a chip which has Arduino support (based on CT_ARM: here CT-ARM User's Manual - Google Docs

They released the design online so I ordered the PCB later based on it. It looks exactly the same with the board I have. Cytron has dicontinued the board.

It's a Nuvoton chip, NUC131L2DAE.

Now, the program I developed for it took me 2 years and let's say I just couldn't bear writing new code for it. So I wanted to stick to the Arduino code rather than using their IDE (it's called KAEL).

Now, I've been able to load the code via ICSP from a working Nuvoton chip of the same model into the new board I built using their bootloader called NuLink. I loaded a simple "ADC to Serial" program, and I could read the serial port perfectly well from the newly built board.

However, I couldn't PROGRAM the board from the COM Port. Here's the error:

Sketch uses 4328 bytes (6%) of program storage space. Maximum is 65536 bytes.
Global variables use 80 bytes (0%) of dynamic memory, leaving 8112 bytes for local variables. Maximum is 8192 bytes.
error: Failed to open COM9
Failed uploading: uploading error: exit status 0xffffffff

Now, here's the strange thing. I've changed the FTDI chip twice, still getting the same issues. But I COULD read the serial port's ADC from the pin A0. (works well too!).

And sometimes, some strange thing happens when I plug in the chip. My mouse would stop working for a while, and some wonky things happen on my screen like right-clicks occurring around my desktop without me clicking.

So I'm thinking it's definitely hardware, but I couldn't determine which.

The COM Port is detected in the Device Manager, yes. But when I try to load a simple blinking code, it says "Failed to open COM9". Changing the COM Port number didn't help too.

Anyone?

Mod edit: What follows is probably AI generated and likely to be of little value.

It seems like there might be a hardware issue affecting the communication between your custom board and the COM port. Double-checking connections, testing with known working devices, and investigating potential interference could help isolate and resolve the problem. Good luck with your troubleshooting!