Can UART output be read by RSxxx decoder?

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QuinnMusulin
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Joined: Mon Aug 30, 2021 1:23 am

Can UART output be read by RSxxx decoder?

Post by QuinnMusulin »

Hi Pico Forums,

I am new to using UART and I have a question about UART output and the RS232/RS422/RS485 serial decoder on the picoscope 2204A.

I'm trying to get a system working which sends data via a 550 USART (in asynchronous mode) from an LPC-Link2 development board to a computer, with the computer running PySerial.

I bought the picoscope to monitor the UART output to check it before I get it working with PySerial.

I am currently only using two wires, a GND and Tx, from my micro to the picoscope and having no luck getting the correct data using the RS232/422/485 serial decoder.

I have a feeling that the UART output I am sending is not compatible with the RS232/422/485 decoder. Should I be trying to send more signals such as a clock or something for the decoder to work properly? Or should I be trying a different decoder? Or trying to send an RSxxx signal from my micro (I think that's an option too).

Please ask for more info if you need it, I don't know what I am doing wrong, thanks.

Best Regards,

Quinn

Martyn
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Re: Can UART output be read by RSxxx decoder?

Post by Martyn »

Post a psdata file and we can see what your data looks like and how you have set up the decoder, then we can help you.
Martyn
Technical Support Manager

QuinnMusulin
Newbie
Posts: 0
Joined: Mon Aug 30, 2021 1:23 am

Re: Can UART output be read by RSxxx decoder?

Post by QuinnMusulin »

Hi Martyn,

Please find attached is my .psdata file.

Something I just noticed is that the serial decoder is trying to set itself to a much higher baud rate than what I initially set it to. I initially set it to 9.6k baud and let it run for a bit, but when I check it again and it has auto set to some custom baud rate in the Mbaud range.

Maybe I am sending signal at a far higher rate than I think? My initialisation settings are 9.6k but maybe something is going wrong with that.

Regards,
Quinn
Attachments
20210831-0001-data for Pico forum.psdata
(77.36 KiB) Downloaded 434 times

Martyn
Site Admin
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Posts: 4052
Joined: Fri Jun 10, 2011 8:15 am
Location: St. Neots

Re: Can UART output be read by RSxxx decoder?

Post by Martyn »

There is no data in the psdata file.

I would suggest changing the timebase to 2ms/div or slower, and using a trigger at 1V and positioned at 20% so that you can capture a data packet clearly on the screen. You may need to adjust these settings for your particular setup and depending upon the actual data rate of the serial bus.
Martyn
Technical Support Manager

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