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mhoward
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Joined: 05/01/2026
Location: United States
Posts: 2

Posted: 10:04pm 05 Jan 2026

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I recently put together a PicoMite so I could program in BASIC. I would like to do this
"old school" if possible. I have a VT100 terminal with a RS232 serial port and I purchased an Adafruit RS232 Full Breakout module (part # 6253). I'm not sure how to
connect the module to the PicoMite and also how configure it. If possible I would like
the USB port and the RS232 port to be active at the same time. I would really appreciate some help with my project.
Thanks,
Mike

homa

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Joined: 05/11/2021
Location: Germany
Posts: 524

Posted: 10:19pm 05 Jan 2026

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COM1 Valid pins are
RX: GP1, GP13 or GP17
TX: GP0, GP12, GP16 or GP28

or

COM2 Valid pins are
RX: GP5, GP9 or GP21
TX: GP4, GP8 or GP20

with your Adafruit RS232 Full Breakout module (part # 6253).

AND

OPTION SERIAL CONSOLE uartapin, uartbpin [,B]

Specify that the console be accessed via a hardware serial port (instead
of virtual serial over USB).
‘uartapin’ and ‘uartbpin’ can be any valid pair of rx and tx pins for either
COM1 or COM2. The order that they are specified is not important.
The speed defaults to 115200 baud but can be changed with OPTION
BAUDRATE. Adding the "B" parameter means output will go to "B"oth
the serial port and the USB.

OPTION SERIAL CONSOLE DISABLE

Revert to the normal the USB console.
These commands must be run at the command prompt (not in a program).

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2916

Posted: 11:48pm 05 Jan 2026

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Adafruit RS232 Full Breakout module (part # 6253) uses the TI MAX3243 chip.
The data sheet says its maximum RS232 signal voltages are +/-7V with a maximum difference of 13V.

Much older equipment requires a minimum of +/-10V and maximum of +/-20V as that was the original RS232 specification.

Several decades ago , after encountering that issue, I made a transistor inverter / level shifter / +/-12v voltage generator module for Rx and Tx. If you need that I will try to find the circuit.

Also some old equipment requires additional hardware I/O signals that your module can pass through but the Pico does not supply/accept.
If that is the case you may be able to deal with that in a program but the console and editor could be a problem.

mhoward
Newbie

Joined: 05/01/2026
Location: United States
Posts: 2

Posted: 12:17am 06 Jan 2026

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When I input command: OPTION SERIAL CONSOLE GP5, GP4 [,B] I get Error: Expression Syntax.
I have used my VT100 on a Raspberry Pi 4b with a serial hat and it worked fine.

PhenixRising
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Joined: 07/11/2023
Location: United Kingdom
Posts: 1688

Posted: 12:57am 06 Jan 2026

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Only on my phone, no docs.

I suspect that the [,B] is where you specify the baud. Just a numeric value, without the brackets which usually mean that the value is optional

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2916

Posted: 01:00am 06 Jan 2026

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[,xx] signifies that is where you place an optional parameter. In this case that is "B" so try :-
OPTION SERIAL CONSOLE GP5, GP4 ,B

If you didn't get an error message it has ignored the parameter and you may no longer have the USB console.
If that is the case connect a USB-to-TTL Serial module to GP8 and GP9 plus ground as per the manual then enter :-
OPTION SERIAL CONSOLE DISABLE
to restore the USB console so you can enter :-
OPTION SERIAL CONSOLE GP5, GP4 ,B
Edited 2026-01-06 11:07 by phil99

lizby
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Joined: 17/05/2016
Location: United States
Posts: 3535

Posted: 01:01am 06 Jan 2026

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mhoward said When I input command: OPTION SERIAL CONSOLE GP5, GP4 [,B] I get Error: Expression Syntax.
I have used my VT100 on a Raspberry Pi 4b with a serial hat and it worked fine.

You do know that the B is optional? Either OPTION SERIAL CONSOLE GP5, GP4 or
OPTION SERIAL CONSOLE GP5, GP4, B

PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed

toml_12953
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Joined: 13/02/2015
Location: United States
Posts: 540

Posted: 04:52am 06 Jan 2026

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PhenixRising said Only on my phone, no docs.

I suspect that the [,B] is where you specify the baud. Just a numeric value, without the brackets which usually mean that the value is optional

The B is for Both. Both the USB serial port and the pins can be used when that's specified. You add ,B to the end of the command. No brackets.

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