Re-wired Compaq IPAQ
As a LCD for my Media PC I decided to use a broken Compaq Ipaq instead of purchasing a LCD or VFD.
Using an IPAQ will give my media PC a lot of advantages.
Here is a list of functions that the IPAQ will control:
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Control all Media PC basic functions, such as volume, play lists, programs, timers. |
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Act as a voice recorder, and voice feedback device (freeing up the PC's sound card to record, and play music. |
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Display and edit play lists, and manage file. |
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Limited remote control of the PC. |
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Display reminders and e-mail notices. |
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Display music visual feedback |
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Display photo's and videos even when Media PC is Off |
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Anything you can program an IPAQ to do! |
When finished the IPAQ will be mounted to the front of the Media PC, and will electronically rotate via a servo
But first the buttons, light sensor, microphone, speaker, and status LEDs need to be re-wired to work from the front panel.
Here are all the parts that will end up being used in the IPAQ interface.
Starting at the top left: Motherboard, keypad, Battery (Dead) Speaker Microphone, Buttons, Power switch, Status LED's, Backlight LED's (For buttons), Headers, and the LCD.
Before I could get this IPAQ to work I had to replace the LCD, and the LCD connector on the motherboard.
(Which is a soldering feat in itself as it has 90pins, at 0.03mm apart)
First off the motherboard. First I had to reverse engineer all the switches and sensors, then decide how to wire them to the header. (All done with a continuity meter)
List of what had to be re-wired:
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Power Switch |
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Charging LED |
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Reminder LED |
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Light Sensor |
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Recorder switch |
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Microphone |
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Speaker |
First all the area's to be soldered were given a fresh addition of solder to make sure the wire would stick.
Then each was marked with a red marker to make it easier to see the connections to be made.
After about an hour of careful soldering the header is all wired up.
The header was superglued to the PCB.
Here is a pinout of the header:
| Top | Bottom |
| Power Switch | Ground |
| LED 1 | LED common |
| LED 2 | LED common |
| Sensor 1 | Sensor 2 |
| Record | Ground |
| Microphone | Ground |
| Speaker + | Speaker - |
Next the keypad. This will have more connections to be soldered.
All marked up and ready to solder.
Note that each directional pad was cut in half with and exacto-knife.
Strangely the Common connection to all the switches is not grounded until it is inserted into the IPAQ.
Now with the keypad all wired up. The keypad is secured to the IPAQ using two small bolts.
Again the header was superglued to the PCB
Next the power connections. This is the flexi PCB ripped off of the battery.
Why use the battery connection? First so that I can provide battery back-up if I unplug the Media PC from the wall. And second to allow the IPAQ to know when the Media PC is powered off.
The IPAQ will be powered by both the +5volts and the +5volts standby from the PC's PSU. This will allow the IPAQ to be powered when the PC is still off.
But the +5volts standby will be wired directly to the battery connection. Maybe with some regulation to lower it to 4-volts, the standard battery voltage. Since the IPAQ will think that it is running off a battery when the PC is off it will automatically power off after a time out. No software needed.
The Battery connector was taped into place and soldered up to two pins of a header.
The +5 volts running was also wired up to two other pins on this header.
Next the USB connection
Rather than hacking a IPAQ/USB charging cradle I wired my own USB header
This allows me to use a normal CD-ROM Audio cable to connect the IPAQ directly to a USB header on the Media PC's motherboard.
The USB's data signals are wired up to two capacitors that are connected to the USB signals on the IPAQ connector.
All wired up an ready to go.
Testing it after wiring. So far so good!
Next is to build the PCB's to hold the LCD/ buttons, LED's and other parts.
(The USB/Power stuff was actually wired after these two pictures)