Dell Mini 9 Hardware and Upgrades Discuss Dell Mini 9 Hardware and Upgrades.

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vrg3 vrg3 is offline
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Default Keyboard illumination LED modification with pics - 01-27-2010, 09:31 PM

All of my laptops for the past ten years or so have been IBM ThinkPads. When I got my A90 I loved using it but found that it was nearly impossible to use it in the dark! ThinkPads have a little LED called a ThinkLight that illuminates the keyboard when you press the keys in the upper-right and lower-left of the keyboard.

I've since modified my netbook and put in a ThinkLight equivalent; it's a little LED in the display bezel that toggles on or off when you hold the Ctrl key for a few seconds. I also dimmed the power LED a little with some masking tape (I swear, sometimes it was brighter than the screen) and now the little netbook is so much more usable in the dark.

Similar work has been done by Sprite_tm on a Toughbook and tristand on an eeePC.

Here's how I did it. I would imagine these steps would work exactly the same
on a Mini 9. I apologize for the lousy pictures; these were taking with a disposable camera. These pictures are also available at . Anyway, here we go:

I broke off the little tab visible in this picture between the webcam LED cover and the sticker. It's in just the right spot to put an LED without hitting the Wi-Fi antenna or the webcam.


Then I drilled a 1/8" hole in that spot, at an angle.


And cleaned up the edges of the hole.


I harvested a T-1 white LED from a string of LED Christmas lights.


And a pair of 30 AWG stranded wires from a round IDE cable.


The LED fit snugly into the hole and is secured with hot glue.


I clipped the leads short, soldered wires to them, and tacked the wires along the side of the bezel using little bits of hot glue. The positioning of these wires can be a little tricky because it's important that they not get in the way of the bezel clipping back on.


When assembled, the wire comes out through the left hinge.


I soldered a 68-ohm resistor directly to the +5V pin of a USB port (pin 1 of connector JP7). This way there's a minimal possibility of a short, but if a short does happen, the USB controller can cut off the juice. The other end of the resistor is connected to the wire going to the anode of the LED.


A microcontroller manages the LED. This is an ATTiny13 (in its 0.150" SOIC form it's the smallest AVR that can be easy handled by a hobbyist). +3.3V and ground are taken from JP14 pins 1 and 4 respectively. The ground pin is soldered directly to the pad and the Vcc pin is connected using one of the leads cut off the resistor. These two are sufficient to hold the chip in place. The chip is also connected to pins 1 and 11 of the keyboard (so it can monitor the Ctrl key) and to the cathode of the LED.


The AVR is programmed with the following code meant to be compiled with AVR-GCC (the code is also attached below):

/* Keyboard LED    *     ________                                 *
 * controller for  *   -|1 o    8|--JP14 pin 1                    *
 * Dell Mini 9     *   -|2      7|--JP12 pin 9                    *
 * * * * * * * * * *   -|3      6|--JP12 pin 11       White LED   *
 *          JP14 pin 4--|4      5|-----------------------|<----+  *
 *                      |________|               68 ohm        |  *
 *                       ATTiny13   JP7 pin 1----/\/\/---------+  */
#include <avr/io.h>
unsigned char pressed(void){
 unsigned char c,i;
  if((PINB&(_BV(PB1)|_BV(PB2)))==(_BV(PB1)|_BV(PB2))) c++;
 return c&0x80;
int main(void){
 unsigned char c;
   if(c&0x80) for(DDRB^=_BV(DDB0);pressed(););

A view of the entire motherboard, modifications in place. You can also see that the power LED is covered with a few layers of masking tape.


This picture doesn't do a good job of showing how effective the LED is, but here it is anyway. You hold the Ctrl key down for a few seconds to toggle the LED on or off; this works independently of operating system or BIOS.

Attached Thumbnails
00-bezel.jpg   01-drill.jpg   02-hole.jpg   03-xmaslights.jpg   04-idecable.jpg  

05-glueled.jpg   06-wireled.jpg   07-assembledisplay.jpg   08-5volts.jpg   09-mcuconnections.jpg  

10-motherboard.jpg   11-finished.jpg  
Attached Files
File Type: txt mini_9_kb_led.c.txt (807 Bytes, 12 views)
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rrfranczak3 rrfranczak3 is offline
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Default 01-27-2010, 10:15 PM

nice job, looks good, seems like a lot of work though...I think a small attachable book light would also do the same job....but yours is nice too..

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TobyRhino TobyRhino is offline
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Default 01-28-2010, 07:18 AM

Sweet mod. I really like the ctrl to toggle on/off.
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vrg3 vrg3 is offline
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Default 01-28-2010, 11:38 AM

rrfranczak3 - Hardly seems a fair comparison -- an attachable book light is a whole extra piece of hardware to carry around and power. Kinda like the difference between having a wheelchair and having working legs.

TobyRhino - Thanks! I was also thinking that with the addition of a small MOSFET the Ctrl-toggle thing could be used to control power to bigger accessories, too. It could be kind of an alternative or adjunct to the awesome Team MRB Power Isolator Module. I was thinking of trying Tom's GPS mod on a Mini I bought on eBay; maybe I'll see how that works.
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neg2led neg2led is offline
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Default 01-29-2010, 03:43 AM

Would I be able to buy a pre-programmed ATtiny off you? I don't have the wherewithal to program them (though i do have a USB ISP programmer, it seems a bit hard)... I'd like to do this with my own mini9.


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vrg3 vrg3 is offline
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Default 01-29-2010, 06:15 AM

Sure, neg, I'd be glad to program one for you. Based on your signature I'd guess you're not in the US, so we'll have to figure out a good way for me to send it to you. Wanna shoot me an email at vikashgoel at gmail dot com?
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mrp192 mrp192 is offline
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Default 01-29-2010, 09:20 AM

This is sweet.. But it would be AWESOME if it could backlit the keys. so a light behind the keys.. just my 2 cent.. still looks good..
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vrg3 vrg3 is offline
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Default 01-29-2010, 03:43 PM


I couldn't figure out a good way to make a backlit keyboard happen. The keys are opaque and there isn't much room around them. I'd love to see it happen though.
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vrg3 vrg3 is offline
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Default 01-29-2010, 05:59 PM

To make them publicly accessible, I posted the pictures up on a Picasa album as well:

Picasa Web Albums - vrg3 - Dell Vostro A...
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strider_mt2k strider_mt2k is offline
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Thumbs up 02-03-2010, 01:04 PM

I really like the way you switch the power on this project.

It looks like that method could be effectively applied to other modifications as a means to turn peripherals on and off as well.

Good stuff!

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avr, keyboard, light, mod, solder

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