# UbiSwitch UART communication issue **URL:** \ **Category:** BotBlox Hardware\ **Tags:** ubiswitch\ **Created:** [January 23, 2025, 11:31am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374 "2025-01-23T11:31:43Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![botblox\_admin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/botblox_admin/32/1_2.png) [@botblox\_admin](https://forum.botblox.org/u/botblox_admin)\ **Post date:** [January 23, 2025, 11:31am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/1 "2025-01-23T11:31:43Z")
_– Copied from customer email –_ Just testing the UbiSwitch module and trying to get the UART working, but all I’m getting so far is the screen below, every time I apply 12V to the module:- ![image001 (1)](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/e57c284d19a1826e75a6147226a4c1bb61140332.png) We use a lot of FTDI USB to serial adapters that usually work really well. Referring to your [UbiSwitch Software Guide](https://store-l0hv1zrcre.mybigcommerce.com/content/UbiSwitch%20CLI%20Guidelines.pdf) the required settings for the UbiSwitch module, happens to be what I normally use, see below…. Using a scope the Tx/Rx lines seems to be connected correctly and puts out a pulse of Tx data as power is applied. Tried changing some of the settings incl baud rate but the settings above seem to work best. ![unnamed](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/a61c6770bc0dd1c8e244db578f6e060cbc7da746.png) Is there anything else you might be able to think of? ---
**Author:** ![josh\_elijah](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/josh_elijah/32/568_2.png) [@josh\_elijah](https://forum.botblox.org/u/josh_elijah)\ **Post date:** [January 23, 2025, 11:32am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/2 "2025-01-23T11:32:14Z")
Whats the part number of the FTDI USB converter you are using? ---
**Author:** ![botblox\_admin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/botblox_admin/32/1_2.png) [@botblox\_admin](https://forum.botblox.org/u/botblox_admin)\ **Post date:** [January 23, 2025, 11:32am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/3 "2025-01-23T11:32:41Z")
_– Copied from customer email –_ > **[US232R-10-BULK | FTDI Chip RS232 USB A Male to DB-9 Male Converter Cable | RS](https://uk.rs-online.com/web/p/interface-adapters-converters/0429274?gb=a)** > > Buy FTDI Chip RS232 USB A Male to DB-9 Male Converter Cable US232R-10-BULK. Browse our latest Interface Adapters & Converters offers. Free Next Day Delivery available. ---
**Author:** ![josh\_elijah](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/josh_elijah/32/568_2.png) [@josh\_elijah](https://forum.botblox.org/u/josh_elijah)\ **Post date:** [January 23, 2025, 11:33am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/4 "2025-01-23T11:33:15Z")
Hmm… That’s RS232. This is TTL level serial (3.3V and GND). That won’t work with UbiSwitch, needs to be TTL level serial. ![image-Jan-22-2025-06-15-41-8145-PM](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/6f432d57122d7cba00e92435b3c66837db251018.png) I’m worried you may have fried the chip on UbiSwitch. It does still appear to be outputting which is good. Do you have a TTL level serial to USB converter? ---
**Author:** ![botblox\_admin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/botblox_admin/32/1_2.png) [@botblox\_admin](https://forum.botblox.org/u/botblox_admin)\ **Post date:** [January 23, 2025, 11:33am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/5 "2025-01-23T11:33:36Z")
_– Copied from customer email –_ Strange if that’s the reason, as all of the designs I’ve done over the last 10/15yrs o/p a 3.3V RS232 signal and that works fine with all of the FTDI USB converters we have? The recommended converter in your data sheet actually uses a FTDI device…. [Moyina USB to Serial Converter, USB to TTL Adapter for Development Projects - Featuring Genuine FTDI USB UART IC ‘FT232RL’: Amazon.co.uk: Computers & Accessories](https://www.amazon.co.uk/Serial-Converter-Featuring-Original-FT232RL/dp/B075N82CDL) ![](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/2daeaa8b5f19f0bc209d976c02bd6acb51b00b0a.gif) ---
**Author:** ![josh\_elijah](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/josh_elijah/32/568_2.png) [@josh\_elijah](https://forum.botblox.org/u/josh_elijah)\ **Post date:** [January 23, 2025, 11:34am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/6 "2025-01-23T11:34:21Z")
Do we know the voltage output swing on your converter? On the datasheet of the part you’re using, it looks to be ±5V, which would not be compatible with the 0-3.3V swing. ![image-Jan-23-2025-10-08-57-6500-AM](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/13f6c0c7792274a3b1a1d702474d3c70958f7fc0.png) This is different to the output of the TTL UART converter we specify. ![Screenshot 2025-01-23 at 10.09.45](https://canada1.discourse-cdn.com/flex027/uploads/botblox1/original/1X/1322755fcfe769f934f253757b0499fae6d33c88.png) It is worth clarifying that RS232 is not the same as TTL serial. TTL serial is single-ended, typically 0 - 3.3V or 0-5V. RS232 is typically ±5V (though it can swing as much as ±15V, though not from a USB powered converter), so it swings below 0V. I’m 90% sure this is the issue. It’s a pretty common confusion. The UART pins on UbiSwitch interface directly with the pins of a 3.3V microcontroller. So it’s not a RS232 signal, it’s a TTL UART signal. ---
**Author:** ![botblox\_admin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/botblox_admin/32/1_2.png) [@botblox\_admin](https://forum.botblox.org/u/botblox_admin)\ **Post date:** [January 23, 2025, 11:34am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/7 "2025-01-23T11:34:44Z")
_– Copied from customer email –_ That makes a bit more sense if you are saying the UbiSwitch module doesn’t have a RS232 chip to convert the uProc UART signals… I’ll see if I can order Moyina Amazon converter then…. ---
**Author:** ![josh\_elijah](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.botblox.org/josh_elijah/32/568_2.png) [@josh\_elijah](https://forum.botblox.org/u/josh_elijah)\ **Post date:** [January 23, 2025, 11:35am UTC](https://forum.botblox.org/t/ubiswitch-uart-communication-issue/374/8 "2025-01-23T11:35:06Z")
Yes that’s right, apologies I should have been clearer. It’s not RS232. Let me know how you get on.