Test procedure:

1. Use a jumper header to shortcut pin 6 and pin 7 to physically loopback the TX/RX on UART1
2. Press and hold the key on the Raspberry PI PICO and plug in the USB cable. Send the "pico-uart-bridge-v3.0.uf2" file to the USB drive
3. Start Teraterm, "New Connection" and select the port with the loopback and set baudrate to be 115200 BPS and no flow control Make sure when you type, you can see echo in the window, which indicates the physical loopback is working. If not, choose the other USB uart port
4. In the Teraterm, "File->Send File..."->Select the file "wait_regex.ttl" from the default path (from Teraterm installation place). You will see character missing as listed below.
5. I tested using a CP2102 USB UART using same loopback test procedure and did not see any character missing

Original File sent by Teraterm (no line/character delay)

; sample macro of Tera Term ; ; File: wait_regex.ttl ; Description: wait command with regular expression ; Environment: generic ; Update: 2005/10/15 ; Author: Yutaka Hirata

connect '192.168.1.2 /2 /ssh /auth=password /user=yutaka /passwd=yutaka'

while 1

sendln 'uptime'

; waitregex 'Longhorn' '.@sai' 'Pentium\d+' 'TeraTermX{3}' waitregex '(You).(log\w+).*(this)'

int2str s result
messagebox s 'result'
messagebox inputstr 'inputstr'
messagebox matchstr 'matchstr'
messagebox groupmatchstr1 'groupmatchstr1'
messagebox groupmatchstr2 'groupmatchstr2'
messagebox groupmatchstr3 'groupmatchstr3'
messagebox groupmatchstr4 'groupmatchstr4'

sendln 'cal'
wait 'yutaka'

pause 3

endwhile

Actual shown in the window and you will see quite a lot of characters are missing. If in the "Setup->Serial" and put 1ms delay on each line, then no character missing happens. It might be (my ) some issues in the FIFO management or some code is blocking the execution for too long and causes the FIFO overflow.

; sample macro of Tera Term ; ; File: wait_regex.ttl ; Descripion: wait command with regular e ; Update: 2005/10/15 ; Author: Yutaka Hirata

connect '192.168.r=yutaka /passwd=yutaka'

while 1

    sendln 'uptime'

; waitregex' 'TeraTermX{3}' waitregex '(Yo).(log\w+).(this)'

    int2str smessagebox inputstr 'inputstr'
    messagebox matchstr 'matchstr'
    matchstr1'
    messagebox groupmatctr2 'groupmatchstr2'
    messagebox
    messagebox groupmatchstr4 'groupmatchstr4'

    sendln 'cal'
    wait 'yutaka'

    pause 3

endwhile

Hello, thanks for this project, it helped me going on my project where I need USB to UART bridge. One issue I found - when I put a physical loopback on the UART, send a byte buffer of some 100 bytes or so, I receive less bytes back on the USB CDC device. I have now tried the sending in Windows in Python script, and on a dedicated device with native C++ code - in both cases this loopback test looses data. While I dive into the troubleshooting, do you have any advice on what might be causing this ? Thanks, Paul.

Hi,

Thanks for this great piece of work. One thing I want to use it for requires communication at some odd baud rates.. 518400bps is one, 1036800bps is another.

However, when I try to use these baud rates with the Pico, minicom defaults back to 9600. I have tested 115200/230400/460800 & 921600bps successfully.

Is there anything that can be done to allow these strange speeds to work? Tested with the lastest version of pico-uart-bridge on Linux Mint 20.1 (AMD64).

Looking a little into it, it seems this may be due to the clock being used?

Title. Need to hold down BOOTSEL to get it to recognize as a USB device. Then requires reflashing. After flashing, unplugging and replugging doesn't even make the Windows USB insert noise, and device manager shows no changes.

Currently the serial number "000000000000" is hard-coded. This will lead to problems when two RPico uart bridges are attached to the same computer because their device node are ambiguous. With this commit the unique 8 byte ID of the flash chip is used as serial number encoded as hex. Thus two bridges can be safely attached to same computer by using /dev/serial/by-id/usb-Raspberry_Pi_Pico_... device nodes or appropriate udev rules.

Hello, do you see a simple way to provide DTR and/or RTS.

There are projects which could use a DTR. One example could be Chinese diesel heaters or programmer adapters for VHF radios.

They have in common that they use a trick to multiplex RX/TX on one line with the DTR line and 2 transistors.

If the RPi pico would simulate this behavior and would switch TX to high impedance if DTR is set this would become the perfect programming adapter as no additional hardware would be needed.

DTR and RTS could be useful anyway if 2 GPIOs would be used.

Looking for some assistance using your pico-uart-bridge to flash an ESP device via esptool.

I currently keep getting timeouts through ESPtool. When I connect to minicom and look at the ttyACM0 device and power cycle the ESP chip on UART0, i do see activity, but can't seem to get flashing via ESPtool to work.

Any advice on getting this to work with esptool?

Thanks!

I'm trying to program a CC1352 via pico-uart-bridge and using the SmartRF programmer (The official software for programming that chip) but nothing happens. I use an osciloscope to see the TX port output. When I click the "program" button, TX don't send anything, but when I open the serial monitor of Arduino, TX sends what is suppose to send when I clicked the "program" button.

Is there any instruction that makes the Pi Pico waits for the command of Serial Monitor open?

Thanks for the software !

I tested HWFC with an FTDI cable @ 1Mbits and it seems to work alright. Also added DTR functionality (useful for e.g. programming an arduino board).