Organiser with opened extension boxHardware extension box for the Psion-Organiser II

by Dr. Wolfgang Strickling

There are some ideas for a hardware extension, accessing the top slot of the Psion Organiser II. They are listed and well documented on the very useful Organiser hompage at  http://members.surfeu.at/org2/org2.htm.

A further extension, based on ideas mentioned above, is my box. It provides 16 user definable parallel data output lines and 8 parallel input lines. My purpose is to register meteorologic data during solar eclipses and to control photographic cameras during the eclipse. But  with special software ist is possible to use this equipment for many other hardware applications and to connect your organiser to your PC. More details about the eclipse project on my Psion eclipse page in German language.

For the slot pinout look at http://members.surfeu.at/org2/toppin.htm.


Important for me are:

First, take a look at the circuit.

opened extension box

Left: the opened orgniser top slot extension box.

external plug connectors for meteorologic sensors, cameras an PC connection, internal plugs for the complete Data input and output ports. On the right side a plug for an external power supply

The two 8 bit output latches 74HC273 are addressed by the SOME and the SCK lines of the top slot, whenever the top slot is activated by a Low signal on the the SS3 line. The data input driver 74HC244 is addressed by the SMR line, if SS3 is low. To avoid organiser system crash, R1 (about 100 k) at SS3 line is required.

The adress lines can be switched on and off by the following procedures. For port  reading or writing it is important to set the DDE Register (data direction register) to a correct value (%00 for reading and %FF for writing).

Simple procedures for accessing the ports are (% signifies hex data, and # hex address): 

; PowerOn: 
C6 03    LDA B,%03
3F 62    SWI %62      ;activates Slot 3
39       RTS

; Portin: 
C6 03    LDA B,%03    ; First activating Slot 3, otherwise problems with execution from pack
3F 62    SWI %62      ;activates Slot 3
4F       CLR A        
97 01    STA A,#01    ;Set DDE to Input
72 40 17 OIM %40,#17  ;Set SS3 High
72 02 17 OIM %02,#17  ;Set SMR(pin 16) High
71 BF 17 AIM %BF,#17  ;Set SS3 low
D6 03    LDA B,#03    ;Read port 3
72 40 17 OIM %40,#17  ;Set SS3 High
71 FD 17 AIM %FD,#17  ;Set SMR(pin 16) Low
4F       CLR A
18       XGDX         ;Return B
39       RTS

; Portout: 
86 FF    LDA %FF      ;
97 01    STA A,#01    ;Set DDE to Output
72 40 17 OIM %40,#17  ;Set SS3 High
72 08 17 OIM %08,#17  ;Set SOME (pin 15) High
71 BF 17 AIM %BF,#17  ;Set SS3 low
D7 03    STA B,#03    ;Write port 3
72 40 17 OIM %40,#17  ;Set SS3 High
71 F7 17 AIM %F7,#17  ;Set SOME (pin 15) Low
4F       CLR A        
18       XGDX         ;Return B
39       RTS

; Portout2: 
37       PSH B        ;Saves B to Stack
72 40 17 OIM %40,#17  ;Set SS3 High
72 01 17 OIM %01,#17  ;Set SCK (pin 10) High
                      ;Reactivation of Slot 3 required after SCK L -> H!
C6 03    LDA B,%03
3F 62    SWI %62      ;activates Slot 3
86 FF    LDA %FF      ;
97 01    STA A,#01    ;Set DDE to Output
71 BF 17 AIM %BF,#17  ;Set SS3 Low
33       Pul B
D7 03    STA B,#03    ;Write port 3
72 40 17 OIM %40,#17  ;Set SS3 High
71 FE 17 AIM %FE,#17  ;Set SCK (pin 10) Low
4F       CLR A        
18       XGDX         ;Return B
39       RTS

As temperature sensors i use I2C (two line) devices, eg. DS 1621 or LM 75. The I2C line is pulled high by a 10 k resistor and if active pulled low by the 74HC273. A diode avoids collisison of high 74HC273 output and low data output of a peripheral device.

Other sensors can easily attached to the hardware box. I use a light intensity sensor (TSL 230 light to frequency converter with programmable sensitivity) or the output of a pototransistor, operating behind a shutter for wind speed measurements. These sensors provide an output frequency due to their input. A software registers the frequency and calculates light intensity or wind speed from it.

To control electronic cameras the data output lines are connected with the remote cable of the camera. My cameras take an exposure, if their remote cable is connected to GND, or if its data line is set to low. For security, a diode is inserted, keeping high (5 V) output levels off the camera. Some of them (eg. my PENTAX A3) work only with 3 V power supply.

If the camera is set to manual exposure ("B" setting), it can realise shutter times from 1/10 s and longer, my Z3 is able to expose from 1/250 s upward. For the Z3 it is necessary, to activate the camera some 100 ms befor the exposure by a second line. This is the line, which activates the exposure meter of the camera (the line, which the  original PENTAX two-stage remote cable swithes first). Without this activation, the camera can only take exposures longer than 1/3 s.

You can download my software including assembler source codes here.

You find a more detailed description of my eclipse software with all these functions integrated in one program on my Psion eclipse page in German language. You can download the international eclipse software here. 

Data exchange with PC

There is also the possibility, to connect the psion with a parallel port of a standard PC. I excange data from the Psion to my pc by this way. Unfortunately i did not succeed in writing data back from PC to organiser and the data exchange is very slow and sometimes providing errors. Simply connect the data input lines D0 to D4 to the parallel Printer output lines D0 to D4
(D0: Pin2, D2: Pin3, ... , D7 Pin 9) and the box's output lines D0 to D4 with the parallel input lines:

As a standard parallel port has only 5 data input lines, data are excanged nibble by nibble with D4 controling handshake protocol.

A windows software (Psionlink, for Win 3.1 and higher) and PClink Psion software can be downloaded here.

© Dr. Wolfgang Strickling.

The organiser hardware extension circuit
Software for the organiser hardwarebox: boxsoftware, PC linksoftware, eclipsesoftware
An application: Psion eclipse page in German language
http://members.surfeu.at/org2/org2.htm, the ultimate Organiser II homepage. Many tips, technical information and second hand devices. Very useful!

back to my Homepage (German language)

Last updated on 2007-03-14
The URL of this page is http://www.strickling.net/orginter.htm