Connecting the Serial Adapter

Discuss peripherals for the XO and power management.

Re: Connecting the Serial Adapter

Postby imscifi75 » Sat Apr 03, 2010 9:22 pm

I have a slightly different problem. Actually two at this point. One deals with the actually Bricked XOs. The ones with what I like to call the Mic light of DOOM. This is the issue of both the power light and mic light staying on. The other is no screen and no mic light.

1) Any known fixes for the mic light of doom? I have hooked up the serial adapter and it spits out forthm+ over and over for as long as it is on.

2) No screen. Plugged in the serial adapter and get
Type 'i' to interrupt stand-init sequence
First stand-init:
DHCP init
memory node

It stops here and will do nothing else. I was able to use "i" to interrupt and get an ok prompt. However, no commands seem to work here. Enter does nothing I can tell. I even tried with a usb and the dev key, but nothing works.

The only information I seem to come across deals with the clock and not the issues I run into when trying repair the "Bricked" XOs here in Birmingham.

There are many many kids who are now without due to the mic light of doom. So, any help would be very much appreciated.

Thank you,

Posts: 1
Joined: Sun May 17, 2009 1:21 am

Re: Connecting the Serial Adapter

Postby ncarrol » Sun Apr 04, 2010 5:39 pm

The troubleshooting guides say that the if the processor starts (via embedded controller {EC}), then the mic LED is on by default and then the firmware turns it off. Hence, if mic LED does not come on, suggests computer hardware problem (no repair ?). If the mic LED does not turn off, then the firmware is not running correctly or there may be other hardware problems.

I suspect you already know this. Does the clean install via USB fail (anticipate the answer is fails) ?

I am researching in order to solve a similar (but different) problem. The output on the serial port is as yours, but there is an error in the flash memory and the boot procedure stops, but further than in your example. The approach I plan to try is to prepare USB with a bootable image as described in

This involves downloading an file, unzipping, and dd to the USB. The XO should boot entirely from USB, if I correctly understand the article. The firmware does have to get far enough to try booting. It will try booting from a USB first, if present. This might then allow loading of a new firmware (existing firmware may be corrupted) or, in my case, repair a flash "can't open disk label package" error on the serial port output.

I will let you know if this works.

As a side bar, my serial port output does not loop and repeat. Is it possible that you should set your terminal parameters to Xon/Xoff rather than hardware flow control ?

Posts: 367
Joined: Mon Aug 25, 2008 12:38 am

Re: Connecting the Serial Adapter

Postby ncarrol » Mon Apr 05, 2010 9:54 am

The above produced USB still requires a developers key, which is more difficult to obtain when the XO does not boot. So, I am also looking for any suggested approaches to repair (in my case the OFW does start correctly, but errors found). Noted the similar error in a new post in the "linux" section of this forum.


Suggest that you repost to a new thread that highlights the particular errors that you observed. Perhaps you will get more and more knowledgeable responses.
Posts: 367
Joined: Mon Aug 25, 2008 12:38 am

Re: Connecting the Serial Adapter

Postby 0blacklist » Tue Aug 24, 2010 2:00 am

I fixed several "bricked" XO's caused by the loose RTC battery using a Sparkfun ( USB to serial breakout board BOB-00718 ($15) and a three wire null modem cable to the XO (TX to RX; RX to TX; ground to ground; do not connect 3.3 volt -- supplied by USB port). The cable connector was a copper foil (tape) pattern on a piece of plastic and was wedged under the pins of the connector of the XO. An alternative is copper wires imbedded in epoxy glue and filed flat with a hobby file. Also needed is a USB A to USB mini 5 pin cable ($4).
Posts: 1
Joined: Tue Aug 24, 2010 1:56 am

Re: Connecting the Serial Adapter

Postby jecourdclearck » Sat Sep 18, 2010 12:41 am

Wow here is really awesome information about OX , I have been searching last two month for more detail about OX connecting Serial Adapter So I would say finally I got my final answer for this thread so thanks for sharing every one opinion in here.
Posts: 3
Joined: Sat Sep 18, 2010 12:30 am

Re: Connecting the Serial Adapter

Postby mrdennmann » Sun Dec 12, 2010 1:13 am

I've read through the "Fix Clock" item also, regarding serial adapters, and dismantling the OLPC device. I'm rather uncomfortable tearing into the machine, to be honest, and I'm not sure where to acquire the various adapters locally needed to properly connected the two machines, and make the repair/upgrade to the latest firmware. Is there a way that I can find someone near Portland, Oregon that has done this particular operation prior, and wouldn't mind walking me through it?
Posts: 1
Joined: Sun Dec 12, 2010 1:09 am

Re: Connecting the Serial Adapter

Postby ncarrol » Sun Dec 12, 2010 5:01 pm

There is a good video here:

It is for removing the Display, but STOP just before removing the display.

The serial port connector is under the back panel which is held by 4 screws accessible from the front by moving the display down a inch (display remains connected) or rotating the bottom edge of the display up. Each screw is about an inch or inch and a half from each corner.

The resetting of the clock requires a second computer (linux / XO or PC) and a serial adapter (3 volts version) with the correct cable connector.

You may be able to borrow the USB to Serial adapter from one of the Repair Centers. See the Mid-Michigan Lending Library at: (bottom of main page).

If you can perform the tasks in the video and have a second computer with a USB port, then you can probably repair your Bricked XO, IF it is the RTC clock problem. The symptom of this problem is no display, but a very brief, one time, flash of the microphone LED (above left speaker) immediately after the power button is pressed.

Best of luck.
Posts: 367
Joined: Mon Aug 25, 2008 12:38 am

Re: Connecting the Serial Adapter

Postby Bahnyen » Thu Jan 20, 2011 7:24 pm

Thank you very much ncarrol, your video is very useful and it help me a lot, also can fixed my problem.
Posts: 2
Joined: Wed Jan 19, 2011 12:42 am

Re: Connecting the Serial Adapter

Postby ncarrol » Thu Jan 20, 2011 10:33 pm


There are two issues that make this more difficult now.

The first is that the clock batteries are now becoming completely discharge if they have not been used. These can only be charged by having the XO powered on (even if there is no display). It takes about 4 hours to recharge a totally discharged battery. Even some of these do not give the firmware messages on the second computer . They give only "+" . This can be corrected by temporarily interrupting the connection to the clock battery after it is charged (also remove main battery an AC power supply). This can be done by pushing the contact of the battery holder or removing the battery. CAUTION: this is dangerous --- the battery holder can be ripped from the mother board. If you must, then firmly hold the holder down and use a twisting motion of a tool under the battery. DO NOT try to pry the battery out of its holder.

The second issue is that XO's with the original software (build 650) will have a false keyboard and mouse failure when the date rolls over to 2011 ( some XO clocks are slow and have not rolled over to 2011 yet). There is a simple software solution: download and install Q2D14 firmware. Set other posts about keyboards under this Hardware section for more details.
Posts: 367
Joined: Mon Aug 25, 2008 12:38 am


Return to Hardware

Who is online

Users browsing this forum: No registered users and 1 guest