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Thinking of developing a digital dash.
http://www.gt4dc.co.uk/forum/viewtopic.php?f=13&t=6240
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Author:  two_OH_five [ Sun Sep 29, 2013 10:48 pm ]
Post subject:  Re: Thinking of developing a digital dash.

I must say having hitched a rude in Chris' car I was quietly impressed. The box just sat there and did its thing

It was able to keep up with all the meltdowns, explosions and general bits dropping off. An extended duty alarm buzzer might be an idea though, or maybe an option to have the alarm go off when nothing is wrong :lol:

Author:  TrackToyFour [ Mon Sep 30, 2013 12:03 am ]
Post subject:  Re: Thinking of developing a digital dash.

Sounds like the ideal techno-geek ICE ...... put me down for one!

Author:  hally [ Mon Sep 30, 2013 8:26 pm ]
Post subject:  Re: Thinking of developing a digital dash.

yayy xmas present
can it be put so i can plug in a wireless obd2 scanner and send to my fone display?

Author:  Nibbles [ Mon Nov 11, 2013 12:48 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Just tried the blue version of the display I'm currently using and it looks awful and is unlikely to be sunlight readable.

I ordered RS 627-1753 as it looked favorite, and it turns out the sizes quoted are a catalogue error. Turned out to be the size of a postage stamp !!!!

Just looked again at the rapid ones, and the range seems limited and not sunlight readable. Serious language problems on the datasheet too so likely problems getting it to work.

The alternative RS ones (COG) are now looking favorite. You buy the backlight separate from the display and can get a choice of colours or full RGB backlight. The LCD module can be sunlight readable and a choice of 1,2 or 3 rows. I'm going for 2 row for readability by old gits like me.
So, ordered part No. 758-8605 and 758-8664 (RS) for evaluation. I'll probably get another prototype run of the display boards done to go with my prototypes to include these displays and the backlit buttons.

Author:  Nibbles [ Mon Nov 11, 2013 12:51 pm ]
Post subject:  Re: Thinking of developing a digital dash.

hally wrote:
yayy xmas present
can it be put so i can plug in a wireless obd2 scanner and send to my fone display?


Just realised I missed this question.

I'm hoping to be able to - one of the big selling points if it works out. I have put a canbus interface on, and canbus is one of the options of OBD2 so provided I can get information on data formats this should be possible.

I will also be looking at doing a simple Toyota OBD / OBD2 converter at some point in the future.

Author:  hally [ Mon Nov 11, 2013 8:57 pm ]
Post subject:  Re: Thinking of developing a digital dash.

that would be the best for me just the simple converter to be hones im surprised it has not been done before

Author:  Nibbles [ Thu Nov 14, 2013 6:29 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Thermocouple amplifier (EGT) working to about 1200 degrees (not calibrated, measuring temperature of a flame compared with a known instrument)

3 axis G sensor working.

Still remaining to test before pre=production run:
New type display (when it arrives)
SD card interface.
CANBUS / OBD2 interface.


I'm having second thoughts about using a low power processor as a bridge between I2C and SD card. I'm concerned that the quantity of data transfer required to handle a FAT file system on the SD card will make it all too slow to be useful.

I'm considering putting another DSpic instead and letting that do all the file handling, then I only need to pass the logging data through the I2C. The downside is that it won't be practical to do a filesystem software upgrade without physically changing a chip. May be a problem as card size and filesystem formats change - as is inevitable in the PC industry.

I will start off as planned to prove the SD interface method. I may then decide to change for the first production batch.

Author:  two_OH_five [ Mon Nov 25, 2013 8:09 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Just throwing this in for information. Might be useful for something

http://www.hobbytronics.co.uk/nokia-5110-lcd

Author:  Nibbles [ Mon Nov 25, 2013 11:22 pm ]
Post subject:  Re: Thinking of developing a digital dash.

While we're doing asides, some useful information I just gained from the Link G4 storm help file

https://dl.dropboxusercontent.com/u/831 ... %20can.pdf



Also some useful links for data for the remaining hardware to comission:

Canbus / OBD2

http://en.wikipedia.org/wiki/On-board_diagnostics
http://en.wikipedia.org/wiki/OBD-II_PIDs
http://www.auterraweb.com/aboutcan.html
http://www.mrfoch.com/Auto/CAN/CAN%E7%9 ... 5765-4.pdf
http://labkit.ru/userfiles/file/documen ... eng%29.pdf

SD card:

http://en.wikipedia.org/wiki/Secure_Digital#File_system
https://www.sdcard.org/developers/
specifically, section 7 of the following:
https://www.sdcard.org/downloads/pls/si ... t1_410.pdf

Not yet looked for detailed info on fat16 & fat32

Author:  Nibbles [ Sat Dec 07, 2013 9:58 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Just a quick update.

I've been working on some other stuff the last 2 or 3 weeks. Since part of that required a prototype radio board with some various designs of PCB aerial to try, there was a spare space for me to add a revised display board layout ready to try the new display with selectable backlight colour.

Still waiting for the display on back order at the moment, due out any day now.

Image

Author:  Nibbles [ Sun Dec 15, 2013 1:06 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Still waiting for the display. It's been 'friday coming' for the last 3 or 4 weeks at RS, now gone to 31/Jan 14. I've now ordered one from elcodis who seem to be the only other company that stock them (over 3000 in stock :) ) hopefully in middle of next week.

After much head scratching for the last few evenings trying to make head & tail of the ISO specs posted above, the CAN / OBD 2 is now working and sending data via a cheap ebay OBD / bluetooth and torque on an android phone.

Made doubly difficult by the pins in the scanner pushing back and not making contact properly (now glued in place) and other such red herrings.

The only strange thing is that the scanner is transmitting address 71F where the standard calls for 7DF, it is happily taking replies from 7E8 as per standard though.

Image

Author:  hally [ Sun Dec 15, 2013 2:45 pm ]
Post subject:  Re: Thinking of developing a digital dash.

i must say your an electronical wizard!

Author:  Nibbles [ Fri Jan 17, 2014 6:07 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Just a quick update.

Not had much time over xmas thanks to friends & family in need so not much progress.

I have finally built up the new display to try. Sadly, RS supplied a plain yellow backlight instead of the RGB one that was ordered - even the bag said RGB. Next delivery of the correct ones due - MAY !!!. So for now it will be yellow unless I get an RGB one in from the states.

IMO it's worth the mild supply problems for the new display. It is much clearer and allows selection of background colour so will be useful for displaying alarm status etc. It doesn't show as much different in the photo but when viewed in real life it is much better.

Image

Author:  NoGT4 [ Fri Jan 17, 2014 7:12 pm ]
Post subject:  Re: Thinking of developing a digital dash.

It will be good to see the RGB display, but the big buttons look cool :-)

Sent from my C6833 using Tapatalk

Author:  Nibbles [ Tue Jan 21, 2014 5:53 pm ]
Post subject:  Re: Thinking of developing a digital dash.

Another update.

I have decided to go for another single prototype at this stage as there are some fairly major changes, especially the SD card as I've had a major rethink and will need a new board to continue development of this. Also, I have just upgraded the CAd system for unlimited pins and jumped from version 6 to 17 !!! I spotted 1 error introduced by this, there may be others. This is why I never put development tool software on 'auto update'.
Board ordered today on a 1 week turnround so not a huge delay in the great scheme of things. I am trying white writing on black background for the front panel to see how it comes out.

I am a little concerned at the moment that program memory is already 33% used with many features still to add, including loads of look-up tables which will eat program memory.

Changes made:

1 - To get the best out of the new display requires more outputs from the processor to drive the different backlight colours which would require sacrificing inputs. Instead, I have added a micro on the display board to handle display, backlight and buttons all via the I2C already present. This should reduce the software in the main processor and will reduce the number of connections between boards to 5 making production easier.

2 - The change of 1 above freed up a number of I/O pins. I was considering driving the SD card direct, but with the concerns about memory use I have gone the other way and introduced a more powerful processor to handle the SD card, again talking via I2C. The SD cards work on blocks of memory, so when using FAT type filesystem rather than direct addressing requires reading a block, modifying it then writing it back - requiring loads of processor time and memory. This will now all be handled locally by the separate processor. All that will be required from the main processor via I2C is the command to open the file, then the actual data to store at the appropriate intervals, then finally a file close command.

3 - I have changed the way of selecting pull-up resistors. This will be done via dipswitches inside the unit rather than previously by linking in the plug externally. This has allowed me to reduce from a 37 way to a 25 way connector which fits in the box better. It requires opening the box (2 screws) to set, however it's likely the box will be opened anyway to attach fixing screws so overall it should simplify installation.

4 - I have now gone over to the shaped & lit buttons as tried previously. Unfortunately, these are not available in multicolour other than combinations of green, yellow or red. Since the likely required colours to fit in with dash colourshemes are blue, green or amber I have decided to go for single colour buttons which allow these colours and will be specified at the time of ordering.

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