Comments on: DIY digital speedometer using PIC microcontroller

By: Tanvir

Tanvir — Mon, 30 Jan 2012 04:38:38 +0000

Hi Meguitarist, Mike and Peter, I have not seen any response from Jeff (I don’t know if he may have replied off-list) but here are some points to help you…

Meguitarist: The free version of Sourceboost compiles it very well except that I had to rem out the line#38 which says ‘#define _DEBUG’ so my line looked like this ‘//#define _DEBUG’ and compilation was successful. Sorry I have no idea about mickroE.

Mike & Peter: see my reply above regarding removing a line before compiling.

Peter: you keep the button pressed and display shows ‘drag’ push once and display will show ‘CAL’ now while driving steadily at 50 keep the button pressed and it will start calibration. After few seconds the display will become normal showing current speed. If not successful then try again – it will work.

I hope it helps. If still you want then I can send my compiled .hex file. Contact me at ‘tanvir734[at]gmail.com.

Regards

By: notebook mouse

notebook mouse — Tue, 24 Jan 2012 04:13:47 +0000

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By: Peter

Peter — Wed, 04 Jan 2012 11:08:58 +0000

Hi Jeff, I found your speedo. Great Work….. I’m looking for something like this for a long time. The only problem i have is compile the C-File. Tried Sourceboost but always get errors. Could you please send me the Hex-File or ASM?
How do i get into calibration mode? Is the callibration still driving 50?? I would like to build it into my good old Volvo 740. Thanks a lot………… :-))

By: mike

mike — Mon, 26 Dec 2011 21:07:18 +0000

hello
I have try to compile the code if SourceBoost but the compiled code does not work. and now i dont know if is the code or the circuit that is wrong, can some one help me and others that may have the same problem as me, and share a compiled file .hex ready to program in the pic. I will appreciate.

regards

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Mon, 12 Dec 2011 09:25:17 +0000

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By: meguitarist

meguitarist — Fri, 18 Nov 2011 04:18:42 +0000

Hello Jeff,

Wonderful project! I’m thinking of putting this project on my bicycle, how can I getting the C source code compiled in mickroE for pic & program?

By: Tanvir

Tanvir — Sat, 12 Nov 2011 17:40:43 +0000

Thanks Jeff for a wonderful DIY project. Today I ‘test-drove’ my DIY digital speedometer. It works great except for jitters in the display. During acceleration or deceleration, as the speed is varying continuously, there is no jitter. While driving at a uniform speed minor variations cause the display to oscillate between two values causing jitters.
I don’t know much about working or programming of this speedo but I think instead of calculating delta t between every pair of pulses and updating the display it might be more reasonable to sample/count pulses for 100 or 300 milisec and update the display every 0.1 or 0.3 sec. I feel it may provide more stable display. Maybe someone out there with good programming experience try this out.
I used 16F628A PIC instead of 648a and there was no problem. I had to REM out a line in the speedo.c file before Sourceboost would compile it. Similarly I needed to ‘set’ the configuration words in the programmer before burning the .hex file to PIC. I wish there was a PCB for this project as making it on a strip board was a pain in the neck. I also changed the schematic a little bit and inserted an LDR based portion to automatically dim the display in darkness. Also I added an opto-coupler in the input section to smooth out the pulses. As mentioned in an earlier comment the pin connections shown will give a weird display and the sequence given in that comment worked fine.
Thanks again to Jeff and all the persons whose comments really helped me a lot. It is a nice project which leaves one with many new ideas to try and play with.

By: logitech racing wheels

logitech racing wheels — Wed, 09 Nov 2011 08:44:55 +0000

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By: Warren

Warren — Fri, 28 Oct 2011 02:13:52 +0000

Soren,

Yes, the PIC16F648A has internal hardware timers, so you don’t require an external quartz crystal.

If anyone is having trouble with programming the microcontroller, do a google search as there is plenty of resources on the web about all types of microcontrollers.

Jeff, thanks for the help on diy digital speedos. I’m going to set one up for my motorcycle, will let you know how I go. I may make a seperate gear indicator that learns from the speed and current RPM.

Cheers
Warren

By: Soren

Soren — Sun, 02 Oct 2011 10:51:06 +0000

Hi Jeff
I see you havent been commenting fore a while, however i hope you see this message.
First of all thanks for the great project description, I have one question though: Does the chip know the time? I seen other projects where they add a clock(crystal) to have a time indikation, but you don’t have one! You need a time indicator to get KPH/MPH etc., how does that work???

Brgds.
Søren