Connecting a PICAXE Microcontroller to a Casio FX-9750G Plus Graphing Calculator: The 2008 First-Edition Manuals (RIGEL / CASIO Data Logger)
Year: 2008
Type: article
Abstract: Two companion manuals written in July 2008, deposited unaltered as the original Microsoft Word documents in which they were written, together with PDF renderings for reading. Connecting the PICAXE 08M and PICAXE 18X to the Casio 9750G Plus graphics calculator was created on 3 July 2008 and last modified on 17 July 2008 over 140 revisions. RIGEL / CASIO Data logger manual was begun on 25 July 2008 and last modified on 20 September 2008 over 99 revisions. Both retain their original file properties and both carry the copyright line "July 2008 © Michael Fenton". Together they document the SB-62 interface circuit, the Casio legacy serial protocol as it was then understood, working PICAXE 08M and 18X code for both data logging and remote control of a robot, and the classroom sensor work of that year — a portable sensor unit, home-made thermistor and light sensors, and an ultrasonic rangefinder. The interface circuit they describe is unchanged nineteen years later. A 1N4148 small-signal diode, bar toward the microcontroller, in series with the line to the calculator, fitted "to pull the normally high Casio Rx line low". The same manuals note that the Casio "has an active serial in line that sources current" — the open-drain behaviour of the port, recorded here in 2008 and confirmed by measurement in 2026. The second edition, which carries the current circuit, the full protocol description and the interval-logging method, is at https://doi.org/10.5281/zenodo.22003135. The documents are reproduced exactly as written, including their errors and a stray template title field. Corrections and later findings are recorded in the second edition and in the priority disclosure rather than applied here. The .doc files are the record; the PDFs are provided only for readability. Third-party material, included as evidence. picaxe-forum-thread-20139.pdf is a capture of PICAXE Forum thread 20139, Casio Calculator Communications BCD and Checksum code check (29 December 2011 – 26 July 2019), taken on [date] from https://picaxeforum.co.uk/threads/casio-calculator-communications-bcd-and-checksum-code-check.20139/. It is reproduced for evidential purposes only. Copyright in the posts remains with their individual authors and with PICAXE Forum; this file is not covered by the licence applied to this record. The thread was live at the date of capture and can be verified independently at the URL above; the relevant posts are 191272, 191315, 191347 and 191358.
Author: Fenton, Michael
Institution: Royal Society Te Apārangi
Language: English
Topic: Arduino and IoT Applications
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7203733035