Additional COM port

Technical Support
, , , ,
1

Hello,

We have many Iris Carrier Board V2.0 with the Colibri iMX6 DL512 and Windows CE 7 in one of our products.
Currently we are using 3 RS-232 from the Iris Carrier Board to interface other devices. We know that the Colibri supports up to 5 UART, so we’ve being trying to understand if its possible to use one of the 2 UART remainings from the Colibri to “create” a new RS-232 com port to use as a 4th COM port in our product.

In your website I have found this: WinCE Serial Ports | Toradex Developer Center, where I can add a registry key to enable COM4 or COM5.

Is there any information on how should we interface the remaining UARTs to use as a COM port? I mean, Iris Carrier board only interface 3 of them and “convert” to RS-232 level to be used.

2

Hi, I’m the Toradex AI Assistant.

I might make mistakes. Our support team will step in if needed. If I answered your question, please tick the “Solution” checkbox. For follow-up questions to me, please use @ToradexAI in your post.

Did you like my answer? :+1: :-1:

Hello!

You are correct—while the Colibri iMX6 module provides up to 5 UART interfaces (COM1–COM5), the Iris Carrier Board V2.0 only includes RS-232 level transceivers for 3 of them. However, you can indeed access the additional UARTs and use them as extra COM ports; you just need to handle the RS-232 level conversion externally.

How to Access Additional UARTs (COM4/COM5):

  1. Accessing UART Signals:

    • The TTL-level signals (default 3.3V) for the additional UARTs are available on the Iris Carrier Board through the Extension Connector (X16).
    • For example, for COM4 (UART D), use:

  2. Level Conversion to RS-232:

    • The signals at these pins are at TTL voltage levels, not RS-232.
    • You need an external RS-232 transceiver (such as a MAX232 IC) to convert these to RS-232 voltage levels.
    • You can use a small breakout board or design a custom PCB for this purpose.

  3. Enabling the UART in Windows CE:

    • The registry keys you’ve found here are correct for enabling COM4 or COM5.
    • Example registry settings for COM4:
      [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\COM4]
    "DeviceArrayIndex"=dword:00000003
    "IoLen"=dword:000000d4
    "Prefix"="COM"
    "Dll"="csp_serial.dll"
    "Index"=dword:00000004
    "Order"=dword:00000002

[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\COM4\Unimodem]
    "Tsp"="Unimodem.dll"
    "DeviceType"=dword:00000000
    "FriendlyName"="COM4 UNIMODEM"
    "DevConfig"=hex:10,00,00,00,05,00,00,00,10,01,00,00,00,4b,00,00,00,00,08,00,00,\
     00,00,00,00

[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\COM4\Pinout_Default]
    "colibripin_167"="altfn=3"
    "colibripin_165"="altfn=3"
    • This will make COM4 available in your Windows CE image and accessible to your software.

Summary of steps:

  • Physically access the UART signals from the Iris X16 header or SODIMM pins.
  • Interface them with an RS-232 transceiver circuit.
  • Enable the UART port via registry settings as documented.

For more information, please refer to:

Let me know if you need guidance on any part of the configuration process!

Best regards,
Toradex AI Assistant.

3

Unfortunately, the Colibri iMX6 X1 pins (165, 167, 169, and 171), which are required for UART4 and UART5 interfaces, are not routed to any connector on the Iris carrier board.

image
image705×296 34.1 KB

image
image606×367 21.6 KB

4

Hello @alex.tx. Since those pins are not available on Iris carrier board, what are the options that I have to have COM4 available for my product?

5

You can either build your own custom carrier board or use the Colibri Evaluation Board, which exposes all pins from the SoM’s edge connector.