Compass Datalogger

[Electron]

Hi,
My name is John
I have need for a Datalogger project to
Log data from a Digital Compass Module.
This Data is NMEA 0183 Protocol.
Sentence data is transmitted @ 4800bps.
at a rate of 1 sentence every 4 Seconds.
The Sentence Format is as follows:-
$C331.6P0.8R-3.0*4E
Where "C" is Compass Heading
" "P" is Pitch
" "R" is Roll
*4E is checksum
16 Bytes per Sentence Maximum [After Parsing]
I will interface the Compass Module to
a uM-FPU V3.1 Co-Processor chip pin 9 [SERIN] via MAX232
RS232 converter.
I am using this chip because it has an NMEA Parsing Function
and strips the checksum etc,and has a 200 byte sentence buffer.

Basically what I want to achieve is to read the sentence
buffer via uM-FPU V3.1 pin 8[SEROUT] into a PICAXE18X [4Mhz] @ 4800 Bps
and store the NMEA sentence data sequentially to a 24LC256 EEPROM etc.
I probably would only need to store 10 sentences,but more would be OK.
I would then like to read the EEPROM data and send it @ 2400 Bps
to a Standard 2 line 16 character Serial LCD Display.
I have the display driver [FRM010] and a suitable display.
If possible when reading the EEPROM I would like to have the facility
to vertically scroll the display up/down via a SPDT Centre OFF Momentary
Toggle Switch etc.
At a later date a RTC may be required to time and date stamp data.
Guys this is relatively new territory for me and I would be extremely grateful
for any tips,issues and possible code snippets that you can provide.
I hope that I am not asking too much.
Regards
John.

 

[BeanieBots]

As this is parsing and using the data via a uM-FPU, your best bet is to do as much as possible within the uM-FPU.
Unfortunately, there does not appear to be many users of the uM-FPU on this forum so you may be better off on the Micromega site.
This document has and gives links to some useful information.

http://www.micromegacorp.com/downloads/documentation/AN039-GC Distance.pdf

I have only had a brief play with it myself and only using the FFT aspects so I cannot offer any specific advice myself on that side of your project.

You may get more response if you break your project down into specific sections. For example, what data you are extracting from the uM-FPU and how you want to store it.

I would expect that your GPS will be able to supply time stamp data so I would not expect any requirement for an additional RTC chip.
Also note that many GPS units have the ability to log data, so it might be better to use that facility and simply use the PICAXE to extract that data via the uM-FPU.

I wish you all the best with this project which is not one for the faint hearted.

 

[lanternfish]

A couple of questions.

1. What is the model number for the compass?

2. Are the NMEA fields for C, P, R of fixed or variable length?

You could step up to a 28X1/X2 and by writing your own parsing program, eliminate the need to use the uM-FPU.

A 28X1 provides a 128 byte hserin buffer. The 28X2 provides a 1024 byte hserin buffer that can background read the serial input.

Mind you, if you already have the uM-FPU then the above is moot.

Cheers

 

[manuka]

Aircraft application? These 3-axis darlings can be $$$! You may have some hybrid mileage with a GPS approach,perhaps using a ~US$50 SparkFun module. Check one below mated to a cheap Uniden UHF CB.