Serial Uart Setting - Garbage Outputs

[rvalvekar]

Hello,
The Serial Setup - 1500000 8N1 prints garbage values on the serial monitor.
Any one knows if there are any other solutions ?

[EABASE]

1. That is a very non-standard UART baud rate. Typically you would expect standard rates of:
[115200, 230400, 460800, 921600], on the serial debug interface.

2. Make sure you're using a good serial to USB converter, as the clock divider need to be accurate and without noise.

3. I cannot properly see the connections in the schematic, nor do I have any documents showing the inner UART diagrams. So without that CPU Reference Manual you can't know how the clock is used for the UART.

2025-0108_002925_CM3588_Plus_2404_SCH.pdf_-_Adobe_Acrobat_Reader_(6.png (48.01 KiB) Viewed 4760 times

2025-0108_002758_CM3588_Plus_2404_SCH.pdf_-_Adobe_Acrobat_Reader_(6.png (69.9 KiB) Viewed 4760 times

[lewac]

Hello,
The Serial Setup - 1500000 8N1 prints garbage values on the serial monitor.
Any one knows if there are any other solutions ?

Not all USB-to-Serial adapters support 1,500,000 baud. Some common adapters like CH340, CP2102, and FTDI chips may have issues with non-standard baud rates.
Try lowering the baud rate (e.g., 921600, 115200) to check if the problem persists.

[HaroPo]

Hi everyone,

I am a pretty happy owner of a CM3588 system with 4 NVME SSD drives.

I am facing the same problem: "Garbage" on terminal screen at boot time.

I expected 115,200 bps 8 N 1 like most of the time and I had to try everything possible without success.
I just tried a manual input with 1,500,000 bps with 'gtkterm' (ran as 'root') from my Linux laptop PC, still No success at all.

Is it possible to change the settings at the Device Tree Structure (DTS) level or by passing the settings at boot time, like I een this before ?


Best regards,
HP


P.S.
I am using a Prolific USB Serial "PL2303".

CM3588's UART pinout is: [R][T][G] with Gnd on the edge of the PCB, Tx_Output and Rx_Input

[Otisamity]

If you have access to an oscilloscope, use it to check the signal integrity of your UART lines. Look for noise, distortion, or incorrect voltage levels.

[HaroPo]

Hi Otisamity,
Thanks for your reply:

If you have access to an oscilloscope, use it to check the signal integrity of your UART lines. Look for noise, distortion, or incorrect voltage levels.

Well, I will try this option when possible to access an oscilloscope (could take me weeks before so...)

Else, What USB <=> Serial adapters are you using ?

(chip inside and, if possible, where to buy from, to increase my chances of getting one that works)

I had all sorts of them until I returned from long oversea trip to discover that a big part of my hardware, software, computers and books disappeared from home with most of the paper documents as well...

Best regards,
HP_