https://github.com/zedstarr/sibo-sat_sync
Setting the system clock in Psion SIBO computers via an attached GPS
https://github.com/zedstarr/sibo-sat_sync
gnss gps opl psion sync
Last synced: 3 months ago
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Setting the system clock in Psion SIBO computers via an attached GPS
- Host: GitHub
- URL: https://github.com/zedstarr/sibo-sat_sync
- Owner: zedstarr
- Created: 2023-07-24T17:25:25.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2023-08-14T08:13:58.000Z (almost 3 years ago)
- Last Synced: 2025-06-03T19:39:47.047Z (about 1 year ago)
- Topics: gnss, gps, opl, psion, sync
- Homepage: https://zedstarr.com/2023/07/21/setting-a-1990s-pda-clock-via-gps/
- Size: 43.9 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# SIBO-Sat_Sync
Setting the system clock in Psion SIBO computers via an attached GPS
---
Psion MC/Series 3/3a time setting via serially attached GPS receiver that outputs NMEA
Uses the CALL $058B to retrieve the "country data" structure - this includes UTC offset (in minutes) and "Summer Time" flag
NOTES: **DATE IS NOT SET - ONLY TIME!**
**FIX STATUS IS NOT CHECKED!**
After opening the serial port we
- get 255 bytes of NMEA
- LOCate GPRMC, get GPS traceable UTC time from next 7-12 bytes
- calc time (in seconds from 1/1/1970) from that and UTC offset and the Psion's "Summer Time" setting
- Add a "delay processing time" fudge factor of ... 1s?
- call OS function $038B to set the time
Time is expressed as:
1690166270 or $64BDE3F3 (32-bit number) - i.e. can be split into $64BD & $E3F3 as below
(as Hex $nnnnNNNN - split into hi & low part $nnnn & $NNNN or just by simple maths ;-) )
Tested working on the MC/Series 3/Series 3a
Assumes a GPS receiver attached to the serial port, running at 9600 8N1
Assumes the GPS has a valid fix
Assumes GPRMC or GPGGA sentences which contain UTC time after "GPRMC," or "GPGGA,"
> $GPRMC,170805.000,A,5337.5945,N,00300.7381,W,0.00,281.17,250523,,,D*7D
> $GPVTG,281.17,T,,M,0.00,N,0.01,K,D*34
> $PGTOP,11,3*6F
> $GPGGA,170806.000,5337.5945,N,00300.7381,W,2,9,1.13,4.2,M,49.5,M,0000,0000*40
The "GenGetCountryData" OS call may or may not be meaningless on the MC - certainly its clock has no concept of "Summer Time"
like the 3/3a does. So `stime%` is set to 1 in the MC's OPL to get UTC to BST working (in summer!). Also (obviously!) all the
graphics commands such as `gAT`, `gPRINT`, etc. are meaningless on the MC (I also removed them from the Series 3 code too).
I also had to change the sentence to search for to GPGGA rather than GPRMC on the S3 & MC, possibly something to do with
serial overruns or maybe something else entirely...?
### **DISCLAIMER**: THIS IS BARELY WORKING CODE! There is minimal error checking, lots of superflous variables & commented-out test code
### **USE AT YOUR OWN RISK!**
Shared in the hope it might prove useful to someone. somewhere ;-)
:: Chris Farrow @zedstarr July 2023 ::
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