From the mbed microcontroller Handbook.

Windows serial configuration

The mbed serial port works by default on Mac and Linux, but Windows needs a driver. These instructions explain how to setup the mbed Microcontroller to use the USB serial port on Windows.

1. Download the mbed Windows serial port driver

Download the installer to your PC, e.g. your desktop.

Download latest driver

2. Run the installer

With your mbed plugged in, and no explorer drive windows open, run the installer:

It will take some time (especially on Vista), and pop up a few 'unsigned driver' warnings, but after a while you should have a Serial port.

Where Next

SerialPC - Communication with a PC
Terminals - Guide to using terminal applications

Troubleshooting

If you have multiple mbed microcontrollers, but the serial port only appears for one of them:

Make sure you run the installer for every mbed; windows loads the driver based on the serial number, so it needs to be run for each mbed you use

If the installer fails because "No mbed Microcontrollers were found":

Check your mbed Microcontroller is plugged in

If the installer reports the message "mbedWinSerial_nnnnn.exe is not a valid Win32 application":

It is likely you are using Internet Explorer to download the installer file, which sometimes seems to only download part of the installer application for an unknown reason
To solve this, download the installer with a different browser (Firefox, Chrome), and try again; this should solve the issue.

If the Installer appears to hang:

Check if windows has popped-up a "unsigned driver/permission" window; these often get hidden behind other windows with nothing to indicate so in the taskbar! Windows may be waiting for you to click "OK"!

If you have any problems, or think this tutorial could be improved, please tell us in the Forum!

Page history

Last modified 03 Apr 2012, by Dan Ros

No tags | 8 comments

8 comments on Windows serial configuration:

Rick Shory

# 27 Oct 2010

A bug I spent a long time tracking down: If using a Palm, HotSync manager will try to grab any new serial port. After installing the mbed serial driver I got cryptic error messages that were no help in diagnosing the problem. Workaround: exit HotSync manager whenever using the mbed serial port. Otherwise HotSync will try to commandeer that port. Then, neither the mbed USB serial nor HotSync will work.

Alex Louden

# 28 Oct 2010

Hi Rick, I suggest making a post in the forum, these pages aren't checked very often.

masugi ito

# 07 Dec 2010

Alex Louden wrote:

Hi Rick, I suggest making a post in the forum, these pages aren't checked very often.

HARGOVAN SUTHAR

# 10 Jan 2011

I have tested serial pc with xp and it works ok with Com 8. I run RTC clock and send current time to PC terminal.But problem is that there is no new line Feed and it goes on writing in same line every second. Hargovind

Ernesto Palacios

# 21 Feb 2011

How about a Driver for the USB module on the target?

I want to communicate LabVIEW with mbeds target USB using bulk, not the serialUSB,

how can i do this??

Mark Watt

# 08 Aug 2011

Can Anyone help me. We are using mbed in a classroom situation where students use different mbeds each time and sit at different computers. we want to have the serial usb available but need to continually reload the driver.Any ideas out there?

Gert van der Knokke

# 08 Aug 2011

If Windows detects the same device but with a different serialnumber (or no serialnumber at all) it will ask for driver installation.

From the web:

Quote:

During device testing, we attach many devices that are identical except for the serial numbers. How can I prevent Windows from asking to install a new driver every time a device is attached?

The method described below causes Windows 2000 and XP to ignore a device's serial number. It's recommended for test environments only.

This registry key controls whether Windows uses or ignores device serial numbers:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags]

It's possible to ignore all serial numbers, though this approach is NOT recommended. To ignore all serial numbers, in the above key, change this value to zero:

GlobalDisableSerNumGen = 1

To ignore the serial number for an individual device, create an entry under the above ...\UsbFlags key. The name must start with "IgnoreHWSerNum" followed by the vendor and product ID of the device. A value of 1 = "disable the serial number."

Example (Vendor ID = 0925h, Product ID = 016Ah):

IgnoreHWSerNum0925016A= 1

Another approach is to boot the system with an Ubuntu LiveCD. The only issues I have with Ubuntu/Linux that if I disconnect the mbed and reconnect it quite quickly the serial port will be ttyACM1 instead of ttyACM0 but otherwise the USB storage system is always connected under /media/MBED_

Tyler Wilson

# 4 weeks ago

Suggestion: for the serial port configuration under Windows, you ought to include the entries to enable the serial enumerator (serenum). That is, something like this (taken from an .inf I did for Pleo):

AddService = Serenum_{Serenum_Service_Inst}

[SerialEnumerator.NT.Services] AddService = Serenum_{Serenum_Service_Inst}

[SerialEnumerator.NT] CopyFiles=SerialEnumerator.NT.Copy

[SerialEnumerator.NT.Copy] serenum.sys_,0x20

The purpose of this is so that using the Windows SetupDi functions, we can locate all mbeds that are connected to the PC automatically, and open the ports with the full device path. At the moment this is not doable - at least I have not found a way (I have working code I have used in previous projects).

Thank you, Tyler

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