1) Output port com ..
If you need an external keyboard for your PDA, and the purchase of BT and IR keypads you can not afford, you can connect to the PDA the usual PS / 2 keyboard via the COM port, the COM port has almost all PDA (unlike USB host) ... to start, you need to lead a normal connector com port (RS232) of the conventional connector CPC, for this you need to find the connector the RS232 (for that I just made out the old cable from the modem), and plug the PDA (for this I used an ordinary whistle from the charger, bundled with my ipaq) also need a soldering iron and solder, and other accessories for soldering .. pinout (which is where the contacts are) can be found on pinouts.ru in particular pinout com port as a rs232 connector located athttp://pinouts.ru/SerialPorts/Serial9.shtml
pinout of the PDA connector can be found there, in particular, pinout of the connector HP iPAQ h19xx, h22xx, h3800, h3900, h4100, h4300, hx4700, h5400, h5500, h6315, h6340, h6365 located athttp://pinouts.ru/PDA/ipaq_22p.shtml
there are tables, we look there identical names of contacts and simply combine the contacts of the PDA connector with the rs232 connector ...
I did it all in this form, but it can work out differently for you, in general, itвЂ™s not important that everything works ...
It should be noted that such a cable is useful not only for connecting a keyboard but also for connecting a mouse, and even a modem.
2) Preparing to assemble the circuit ..
Here is the adapter circuit ..
This scheme is based on the AT89C2051 programmable microcontroller, but for it you need to assemble a rather complicated programmer circuit instead, I recommend using the AT89S8252 microcontroller for it has more memory and is very easy to program ..
To build this scheme, you need:
1) Connector for ps / 2 keyboard "socket"
2) 2 ceramic capacitors 33pf (picot farad)
3) Quartz resonator 24 MHz
4) 10k ohm resistor (kilo ohms)
5) ceramic or electrolytic capacitor 10mkf (micro farad) 16V (volt)
6) atmel AT89S8252 programmable microcontroller in DIP 40 package
7) 4 ceramic capacitor 0.1mkf (micro farad)
8) Integrated Circuit MAX 232 CPE (it is desirable to take CPE and not ACPE and TP, since CPE is cheaper and more suitable for this circuit) in the DIP16 package.
9) RS232 connector
10) Panels for these microcircuits, they can be called SLC and TSR panels, they should definitely be taken, I didnвЂ™t buy it because of my stupidity I spoiled the prototyping board and the microchips themselves, because during the soldering the microcircuit contacts get very hot and the microchips fail from overheating, and if you need to remove the microcircuit from the board, you cannot do it without damaging it ..
11) A prototype board for simulating microcircuits, if you assemble such a scheme for the first time, then it is better to take a board with a larger size I bought a 10x10cm board, since I sang the scheme of such complexity for the first time ...
12) about 5 meters of mgtp, it is desirable that the section was smaller, my section was 0.05mm.
13) 2-pin power connectors.
14) 5v power supply, I used 3 AA batteries as a power source, do not try to use power supplies from mobile phones, because there is a pulsed power supply, and the pulsed power supply will not work.
To build the programmer:
1) 2 resistors 200 ~ 500 Ohm
2) lpt port connector
3) 5 pin connector on the board
I bought it all in the store CHIP and DIP at Metro Kurskaya.
I spent about 500r for all this, but if you buy everything exactly according to the list, it will be about 300-400r.
3) circuit assembly
One of the most complex assembly parts. First, take the very development board, then put it on the radio, they need to get their contacts at exactly the hole on the breadboard it all so calculated. I started with the Connector ps / 2, I installed it on the board, then dripped solder where entered the connector contacts, then cut off from the wire MGTF piece desired us the size, then remove from its edges a little insulation, bare wire cover solder, and then on the side where the pins are located. And so here quietly collect the whole scheme, during the assembly, you will need tsoklevki chips and programmable microcontrollers can be found in the datasheet, and themselves datasheets can be found on the manufacturer's website, AT89S8252 datasheethttp://www.atmel.com/dyn/resources/prod_do...nts/doc0401.pdf
.. To distinguish such details as capacitors and resistors, you will need information about the markings, since most of the elements will either be marked with colors, or with codes, information about the marking of capacitors can be found here:http://www.radioradar.net/spravka/conder.p...avka/conder.php
, marking resistors here:http://www.alfa-elektronik.com/html/articl...t/mark-res.html
.. if you are new to radio engineering, then I would advise you to build small paper envelopes in which to embed elements and on envelopes to write which element lies in them (I did) in order not to accidentally confuse when assembling the circuit .. It is worth noting quartz and condensers need to be soldered closer to the controller, also on the DTR port you can not output the line .. It is also advisable to immediately assemble the programmer, the programmer circuit:
I recommend resistors to hide in the lpt connector itself ... For example, like this:
This is a programmer of another microcontroller (microcontroller), in the scheme of our programmer there will be only 2 resistors ..
It is desirable to ensure that the programmer connects to the board and is not firmly soldered to the MK contacts, for this I indicated a 5-pin connector on the list, which will greatly simplify the life of the M programming ..
4) Microcontroller programming
When the process is complete and the circuit is ready, you can go to the programming of the microcontroller, for this we need the programmer programmer "chameleon" it can be taken from herehttp://atprog.boom.ru/Sindex.html
we also need the вЂњfirmwareвЂќ itself, it is a binary file, you can download it from herehttp://mkmk.ras.ru/iprim/arc/palmtasta2.zip
In arhve be file keyboard.bin this is our firmware microns. unsolder first capacitor and a resistor from rst line of the controller, and solder rst programmer, we connect our scheme to lpt computer, connect the power, run the program chameleon choose boring unit for programming we choose it will be AT89S8252 binary file for programming and program code process .. programming will be highlighted over the tablet, which will tell about it .. then we disconnect from the computer programmer, solder back RST line and you're done .. If you are not sure that he will be able to program the controller, as far as I know, there are special firms that have a special programmer, you can then contact them if it is desirable to build a circuit on AT89C2051 as if there where this chip zaprogrommirovat its application will greatly simplify the assembly process and yet it is the cheapest ..
That's all, it remains only to bring the connectors and build the case, well, this is a matter of creativity .. when everything is ready, install the newtonkey program on the PDA, launch it and enjoy the work from the full-size keyboard in the PDA ..img-18281-IMG_0943.JPG