Source code for Yaris Tachometer

[metalshark]

Originally Posted by CTScott

Switch to a Microchip PIC microcontroller. Same or better functionality for <$5 max and many of the PICs can directly drive LEDs with the outputs.

For example the PIC16F57 is $1.55 and has 20 I/O Pins and runs at up to 20mHz. If you're not comfortable with C or assembly programming, there is even a basic compiler for the PICs.

http://search.digikey.com/scripts/Dk...IC16F57-I/P-ND

Thanks for the info. If I wanted to sell these I'd do as you suggest. I'd rather just release the info as public domain/open source and move on. Porting to the Propeller with tach projects would be something I'd do just to learn Spin and cog assembler. I've programmed in C and assembler in the past so that's nothing new. I'm also on DIYelectriccar.com. On there I advocate using a Propeller to build an AC drive for an electric car. I've been building files on IGBTs, fiber optics, true vector drives and so-on. By building up my skill set I'll have the drive and car ready about the time the lithium batteries are available at a competitive cost. Now a good set runs $20-25K. Not something I'll do while gas costs just $2/gallon.

[JustAnotherAsian]

Originally Posted by metalshark

The BS2 chip scans at 20,000 cycles per second on its clock. The entire code is less than 100 lines. The output display driver section is a rather primitive analog/linear op-amp arrangement but it is very fast. This design is WAY faster in its response than any mechanical tachometer needle can possibly be. The code uses the pulsein command for data and in a worst case situation will generate an accurate RPM number in one revolution of the crankshaft.

^20,000 per second... without delay incorporated, you are correct with the accuracy statement- it will be annoyingly accurate.

Originally Posted by CTScott

Switch to a Microchip PIC microcontroller. Same or better functionality for <$5 max and many of the PICs can directly drive LEDs with the outputs.

For example the PIC16F57 is $1.55 and has 20 I/O Pins and runs at up to 20mHz. If you're not comfortable with C or assembly programming, there is even a basic compiler for the PICs.

http://search.digikey.com/scripts/Dk...IC16F57-I/P-ND

^i was gonna suggest the same thing. i'm sure with enough fishing, someone already put out a tach program in C.

Originally Posted by metalshark

Thanks for the info. If I wanted to sell these I'd do as you suggest. I'd rather just release the info as public domain/open source and move on. Porting to the Propeller with tach projects would be something I'd do just to learn Spin and cog assembler. I've programmed in C and assembler in the past so that's nothing new. I'm also on DIYelectriccar.com. On there I advocate using a Propeller to build an AC drive for an electric car. I've been building files on IGBTs, fiber optics, true vector drives and so-on. By building up my skill set I'll have the drive and car ready about the time the lithium batteries are available at a competitive cost. Now a good set runs $20-25K. Not something I'll do while gas costs just $2/gallon.

^interesting! cost of lithium-ion" batteries will definitely drop within the next few years.

[metalshark]

Originally Posted by CtrlAltDefeat

yes, $50 for just the chip would be way too much, an aftermarket tach would cost less. The Propeller version, however, sounds right up my alley... I think it would look good with rectangle or square LEDs (or rectangle shaped covers) closely set together. It would be awesome to somehow incorporate it into the gauge cluster...

I've figured out how to do that but people with more experience than I already know the cost of this can be shrunk a lot by just going to a cheaper microprocessor. When I get two of these beta test units out into the field I'd rather just public domain all the technical data to a thread/sticky on Yaris-World.com and let the hobby members grow the project. A processor in the BS2 class can be had for about $5 and support up to 4 digital readouts with ease. One like the BS2p40 can support up to 8 digital readouts or even more with serial display panel. At that point its getting into the full dash board display area. This is the type thing the folks at scan-gage are good at. The Parallax Propeller can support a small video display complete with graphics.

[metalshark]

Originally Posted by Shroomster

lol might want to pm PK about this...I've been trying for months w/o success to procure a gauge cluster for him....

send him this link. http://www.parallax.com/Store/Access...%2cProductName

[metalshark]

Originally Posted by CTScott

Switch to a Microchip PIC microcontroller. Same or better functionality for <$5 max and many of the PICs can directly drive LEDs with the outputs.

For example the PIC16F57 is $1.55 and has 20 I/O Pins and runs at up to 20mHz. If you're not comfortable with C or assembly programming, there is even a basic compiler for the PICs.

http://search.digikey.com/scripts/Dk...IC16F57-I/P-ND

I bookmarked it to look at after I catch up on sleep.

[metalshark]

Originally Posted by CTScott

Switch to a Microchip PIC microcontroller. Same or better functionality for <$5 max and many of the PICs can directly drive LEDs with the outputs.

For example the PIC16F57 is $1.55 and has 20 I/O Pins and runs at up to 20mHz. If you're not comfortable with C or assembly programming, there is even a basic compiler for the PICs.

http://search.digikey.com/scripts/Dk...IC16F57-I/P-ND

Even though I'm building my last two BS2 based tachometers I ordered the chip you recommended. Its expanded I/O will allow me to incorporate features already requested by my beta testers, (ambient light sensor/auto dimming & auxiliary digital readout.).

[metalshark]

Originally Posted by CtrlAltDefeat

yes, $50 for just the chip would be way too much, an aftermarket tach would cost less. The Propeller version, however, sounds right up my alley... I think it would look good with rectangle or square LEDs (or rectangle shaped covers) closely set together. It would be awesome to somehow incorporate it into the gauge cluster...

Another Yaris-World member is incorporating the display into the steering wheel on a beta test unit. I'm porting the application over to a better, cheaper uP as suggested by a member that has more experience than I. With the reduced hours at work, I'm starting to make better progress on the hobby.

[metalshark]

Originally Posted by CTScott

Switch to a Microchip PIC microcontroller. Same or better functionality for <$5 max and many of the PICs can directly drive LEDs with the outputs.

For example the PIC16F57 is $1.55 and has 20 I/O Pins and runs at up to 20mHz. If you're not comfortable with C or assembly programming, there is even a basic compiler for the PICs.

http://search.digikey.com/scripts/Dk...IC16F57-I/P-ND

What is the equipment to get started with it run? I talked to a Microchip forum member this morning that is recommending the 16 bit PIC24/dspic trouble being that the starter kit is $300. On the up side the kit comes with a student version C compiler.

[CTScott]

Originally Posted by metalshark

What is the equipment to get started with it run? I talked to a Microchip forum member this morning that is recommending the 16 bit PIC24/dspic trouble being that the starter kit is $300. On the up side the kit comes with a student version C compiler.

You can spend from $10 to $1000 to get going. You can download the student/evaluation versions of the compilers for free from Microchip's website. The purchased version adds optimization, but I seldom compile with optimization, as I find it often messes up critical timing.

$10 Programmer for many processors:
http://robokitsworld.com/index.php?m...fl6nbiqsr52nu0


$50 programmer (USB/serial):
http://www.hobbyengineering.com/H3317.html


Real Microchip programmers:

PicKit2 (directly integrates with Microchip's development system):
http://www.microchipdirect.com/Produ...mid=1&treeid=6

$220 Microchip In Circuit Debugger:
The latest version is the ICD3. I use the ICD2 for most of my development work.
http://www.microchipdirect.com/produ...?Keywords=icd3


To use the Pickit2 or ICD2/3 you have to add a header (or RJ11 jack) to your board to connect to. The two third party programmers allow you to plug the DIP package IC's in for programming.

[metalshark]

Here are the photos at the end of the day. Testing so far: Power supply OK. Input circuit OK. 15 Led driver amps OK. Tomorrow I check out the RS-232 connection.