# Serial comms issue

**URL:** <https://forum.clockworkpi.com/t/serial-comms-issue/20763>\
**Category:** PicoCalc\
**Tags:** help, serial, terminal\
**Created:** [December 14, 2025, 4:46pm UTC](https://forum.clockworkpi.com/t/serial-comms-issue/20763 "2025-12-14T16:46:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Attila\_Molnar](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/attila_molnar/32/15034_2.png) [@Attila\_Molnar](https://forum.clockworkpi.com/u/Attila_Molnar)\
**Post date:** [December 14, 2025, 4:46pm UTC](https://forum.clockworkpi.com/t/serial-comms-issue/20763/1 "2025-12-14T16:46:14Z")

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Hi, folks,

I connect PicoCalc (Pico 2WH, PicoMite/WebMite 6, both versions was tried) to my Win 11 laptop. The CDC driver is installed using Zadig, the Windows device manager shows the serial port as Board CDC (Interface 0) (COM6). I try to connect to PicoCalc using different terminal emulators (Putty, TeraTerm, CoolTerm), but there seems to be no communications.

What might be the problem?

Thanks in advance.

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**Author:** ![Toml\_12953](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/toml_12953/32/11925_2.png) [@Toml\_12953](https://forum.clockworkpi.com/u/Toml_12953)\
**Post date:** [December 14, 2025, 5:19pm UTC](https://forum.clockworkpi.com/t/serial-comms-issue/20763/2 "2025-12-14T17:19:57Z")

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First of all, try one of the 6.01.00RC25a files from the link below. Ernst has done a lot of work fixing serial problems as well as problems with I2C and colors in the editor. You need a TTL to RS-232 converter. Are you using COM1: or COM2: on the PicoCalc? If COM1:, connect the TTL converter to UART0\_RX and UART0\_TX on the side of the PicoCalc. If using COM2, connect to GP4 and GP5 on the side of the PicoCalc. In either case, you’ll also need to connect 3V3 OUT and GND to the TTL converter to power it. If you haven’t stuck on the labels provided in the kit, you really should. They make external connections easier.

[Ernst’s Mods to PicoCalc Software](http://raspi1.mypi.co/download/)

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<div class="post-metadata">

**Author:** ![Attila\_Molnar](https://yyz1.discourse-cdn.com/flex029/user_avatar/forum.clockworkpi.com/attila_molnar/32/15034_2.png) [@Attila\_Molnar](https://forum.clockworkpi.com/u/Attila_Molnar)\
**Post date:** [December 14, 2025, 6:08pm UTC](https://forum.clockworkpi.com/t/serial-comms-issue/20763/3 "2025-12-14T18:08:21Z")

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I simply connected the RP2 microUSB port to the laptop.

This firmware version works like a charm 🙂 thank you!!!