Universal Serial Interface for Sharp Pocket Computers

Introduction

Building and using this interface is on your own risk, there is no warranty of any kind.

And now, lets start:

This article enables you to construct a serial interface for all sharp computers with the 11 pin peripheral interface or the 15 pin serial interface. The interface performs a level conversion any has various jumpers to configure it for the use with your pocket computer and transmission software. The purpose of the device is to link your pocket computer to the serial port of your personal computer. There are different software products you can use on the personal computer side:

Standard Terminal Program

Beside this, there are many transfer programs for the serial ASCII transfer over the 15 pin peripheral interface, e.g. from Simon Lehmayr.

The PC-E220 is also able to work with a Standard Terminal Program, but this model has it's serial interface integrated into the 11 pin peripheral port. The power supply may be remote controlled from pin 5 of the peripheral interface, so you don't need to use a power switch for the universal serial interface circuit. I think, the PC-E220 has the best serial interface, because

• it uses a simple 2,54 mm pinhead
• the big AA-batteries of the pocket may be used for the interface supply too
• the supply may be remote controlled.

• PETOOLS 1.1 has a integrated serial port driver (will be released soon on this site)
• The was an article in the C'T magazine (Go to www.heise.de and search the article archive for C'T 1989, number 3. The title (in german) is "Tore zur Welt"). The SHARP Pocketcomputer Seite von Jerry C has also published a page that with a home made serial interface based on this article.

The advantage of using a standard terminal is that it is platform independent, the files are transferred in ASCII mode and you don't need to switch to DOS mode. The transfer rate is up to 9600 bd (CLOAD/CSAVE: less than 500 bd).

FAZ' Software

Friedi's Software

mode con codepage prepare=((437) C:\WINDOWS\COMMAND\ega.cpi)
mode con codepage select=437

Hardware

    +-------------------------------------------------------------------------+ 
    |            PC-1360                                                      | 
 1 -+                                                                         +-  1 
 2 -+                                                                         +-  2 
 3 -+                                                                         +-  3 
 4 -+                                                                         +-  4 
 5 -+                                                                         +-  5 
 6 -+                                                                         +-  6 
 7 -+                                                                         +-  7 
 8 -+                                                                         +-  8 
 9 -+                                                                         +-  9 
10 -+                                                                         +- 10 
11 -+                                                                         +- 11 
    |                                                                         +- 12 
    |                                                                         +- 13 
    |                                                                         +- 14 
    |                                                                         +- 15 
    |                                                                         | 
    +-------------------------------------------------------------------------+ 

Pin Assignment between Cable A, Cable B and the 2 x 5 Pinhead of the interface board

Pin 8 and pin 14 of the 1,27 mm pinhead (15 pin) of cable B are connected together. 1,27 mm pinheads are available at e.g. at Conrad electronic. If you want to use the internal batteries of the pocket, you can mount a switch between pin 1 of the 2 x 5 pinhead and pin 10 of the pinhead of Cable B (15 pin). With Cable A, this wouldn't make sense, because the widely used CR-2032 batteries would be discharged very fast and the PC-E220 (which has AA-batteries) is able to remote control the power supply.

The Interface Board

Yep, that's it. The parts should be available in every electronic store. All resistors are 1/8 Watt, all electrolytic capacitors are specified with 16V. If you want to use a external battery, connect it between "BATT" (plus pole) and "GND" (minus pole). If you want to use a DC adapter, connect it between pin "DC-ADAP" and "GND". A 9V block would be suitable (put a power switch between the plus pole of the battery and "BATT"). The 78L06 create a stable voltage of 6V. T1 reduces this voltage to an amount of 5V, it may be remote controlled from pin 4 (= pin 5 on cable A). LED D8 is on if the circuit is supplied from a DC adapter. If you use a battery, you can solder a test button between pin "BATT" and "TEST". If it's pressed the LED emits light.

For the first tests, I would do the following:

• Use sockets for IC1 and IC2
• Build up the circuit, but don't insert IC1 and IC2 and don't connect a pocket or the PC
• Connect a supply (DC adapter or ext. battery)
• Check if JP1, pin 1 has 6V to GND (use a voltmeter)
• Set a bridge JP1, pins 1&2 and JP2, pins 1&2
• Now check the voltage on the sockets of IC1 and IC2 (IC1: 5V between pins 7&14, 14 is plus; IC2: 5V between pins 15 and 16, 16 is plus) The voltage may be slightly over 5V, because the is no load and C5 may be loaded over 5V, but that is no problem
• Now turn of the power, insert the integrated circuits and turn the power on
• Check the voltage on pin 2 of IC2 (about 10V to GND) and pin 6 of IC2 (about -10V to GND)
• Turn off the power, set the jumpers right for your needs, connect cable A or B, the pocket and the PC and turn the power on again.
• Ready to go!

Cable A

Use a Plug suitable for the 2 x 5 pinheads, a ribbon cable a 2,54 mm pinhead (11 pin). For my prototype, I used a small piece of experimental PCB to connect the ribbon cable and the pinhead JP1. It is also possible to create a small adapter PCB.

Cable B

That's it. All wrote about cable A is also valid here (but you need a 1,27 mm pinhead), and note the remarks made in the section Pin Assignment between Cable A, Cable B and the 2 x 5 Pinhead of the interface board. Phew, the small pinhead is very tricky to solder at a ribbon cable!

PCB Developers Resources

Description of the Jumpers

Operating the Interface

Jumper Settings for the universal serial Interface for Sharp Pocket Computers

Now have fun with your interface!