Tachometer/RPM II.

Source: http://www.josepino.com/?tachometer2   Tags: microcontroller circuits automobile homemade

PIC: 16F628
CONFIG: XT osc, PWRT ON, MCRL OFF, BODEN OFF, WD OFF

As many people was asking for another version of the tachometer to measure up to 9,999 revolutions per minute (RPM), I decided to create an improved version specially used for automoviles or any other machine that can't reach more than 9,999 RPM.
Taken from http://www.josepino.com
The original version was created to measure the RPM of electrical motors with high accuracy with a range between 60 to 99,990 RPM. This improved version measures between 200 to 9,999 RPM with a 0.3% 97% of accuracy. I do not recommend to use this project for critical applications. Please read the disclaimer at the main page.

The schematic and the pinout information is exactly the same for compatibility reasons. The only change is the HEX code. Here is the pinout information:

Pin 3 defines the Display type: Common Cathode or Common Anode. Connect this pin to GROUND if you are using common cathode 7-segment led displays. To use common anode displays, connect it to VCC (positive)
Pin 4 is the signal input, you can use optical sensors (Fototransistors, fotoresistors, etc), magnetic sensors (Hall effect, reed switch, etc) or using a switch.

Unfortunately, I have no idea how to connect this circuit to a vehicle. If you want to share details about how to attach this circuit to an automovile, I will post this information.

DO NOT CONNECT ANY SIGNAL DIRECTLY TO PIN 4. High voltages can damage the PIC. If the input signal is more than 5 Volts, Use a driver as TTL, CMOS, Amp Operational or Transistors.

The RPM are displayed as units, that means, the RPM indicated in the display is the actual reading from the input pin. This version have a faster sample rate so the reading is constantly updated, you get a faster reading that the previous version. The schematic is the same.

Download the HEX code HERE Right click and "save as..."

NOTE: Use only 10Mhz xtal and 22pf or 33pf capacitors.

Here is a picture of the prototype during testing and calibration The input signal was 3,600 RPM. Please note red displays works better than green or the yellow ones.

Do you want to know how this tachometer works? Here is the algorithm. Sorry, I lost it.

Photos sent by readers:

Francisco Arroyo Garcia sent this photo of his tachometer, a very compact design.

08/10/09 - 18:13:25 Mike MacLeod from South Africa wrote: Hi Jose
Nice compact circuit. Why is pin 13 connected to the decimal point?
Mac
08/10/09 - 18:16:49 José Pino wrote: Regardless this project doesn't use any decimal point, the pin 13 is connected to the display because the same schematic was used for other projects,  if you look at my LED CLOCK project, you can see it uses the same hardware.
On this projects, the pin 13 connection can be removed.
08/10/09 - 18:56:47 Mike from SA wrote: Thanks Jose, I thought it might be for an overspeed warning.
Mac
08/21/09 - 02:23:57 alex from Europe wrote: Hi jose,
it's possible to use the 16F84 instead of 16F628 ??
if so, could you propose the HEX code and schematic please
Thanks in advance
08/23/09 - 10:37:14 Ono from Jakarta wrote: Hi Jose,
nice compact design, could you provide hex-code for 4-cylinder engine?
Thank in advance
Ono
08/23/09 - 19:46:37 David from FRANCE wrote: Comment use for the led bargraph style knight rider 22 led ?
I use LM3915 and LM2917 for tachometer ...
thanks
08/23/09 - 19:53:54 José Pino wrote: Veuillez poser votre question en français.
09/15/09 - 02:04:04 ryan mijares from philippines wrote: hi jose can i connect the ignition coil primary circuit to the input signal? tnx?
09/30/09 - 04:15:11 luis eduardo from colombia wrote: lo que hace falta puede ser un GENERADOR DE PULSOS OPTO ELECTRÓNICO
o un generador de pequeños pulsos con una resistencia en serie
10/02/09 - 23:20:32 Martin from santa fe wrote: hola, la verdad es que no lo logro hacer andar, tengo el pic 16f628a, y la verdad es que no consigo lograr que funcione, sin ninguna señal de entrada el tacometro me queda en 8888 y al inyectarle una señal se resetea una y otra vez, quisiera saber con que programa programaste el pic, asi tambien como el hardware que usaste, al no saber nada hex, me resulta confuso y verdaderamente frustrante, ya que tengo todo armado, revise todo 10 veces, y la unica conclucion a la que llego es que tengo un problema en la programacion, o en el pic, si alguien me da una mano en eso, le estare mas que agradecido.
10/09/09 - 00:32:26 Freddy from caracas wrote: tengo un tacometro digital y quiero calibrarlo, tengo una buena fuente para generar frecuencias , pero no se como y donde meterle las señales meterle
10/16/09 - 16:23:42 Jalen from slo wrote: hey jose,
i need some help on this great project of yours. i can't find your email on your page. Anyway i have built this project using 16f628 and common anode led display. Used 22pF caps and 10MHz xtal as said. I can hardly see your sign "jose" at startup, but my display isn't working. It does not flash, but i can't see all the segments of a number. On the 4th display i can see a "0", the 3rd doesn't work at all, the other two have just one segment turned on. I think there's something wrong with the capacitors. I can send some pics if needed. Tnx in advance.
Jalen
10/19/09 - 23:39:58 RONALDO VIEIRA from RIO DE JANEIRO - BRAZIL wrote: OI JOSÉ, GOSTO DEMAIS DOS SEUS PROJETOS E QUERIA SABER SE É POSSÍVEL VOCÊ ENVIAR UM PROJETO DE VELÔCIMETRO DE 3 DÍGITOS COM AUTO ZERO + ODÔMETRO C/ 7 DÍGITOS SEM RST, O PRIMEIRO PARA MOSTRAR CADA 100MT + ODÔMETRO PARCIAL DE 4 DÍGITOS C/ RST TODOS EM MOSTRADORES INDEPENDENTES USANDO PIC 16F877. OBRIGADO.
rvsinfor@ig.com.br
11/03/09 - 21:37:59 carlos from españa wrote: se podria modificar el codigo para que funcione en un motor de 4 tiempos da 2 vueltas por impulso del cilindro1 o ponerlo que cada 4 impulsos cuente 1 vulta
11/03/09 - 21:47:35 José Pino wrote: No es posible modificarlo.  Se encuentra en desarrollo una tercera version que resuelve todos los inconvenientes de la 1a y 2a version de este proyecto.
11/04/09 - 19:02:20 carlos from españa wrote: muchas gracias esperare el nuevo proyecto con ansias haces un gran trabajo jose.
gracias
11/10/09 - 16:19:38 aliqasim from pakistan wrote: hello... can any body tell.that it work correctly.. thanks..
11/10/09 - 19:00:53 wilmer from vzla wrote: Que paso con la pagina en español, estuve usando este circuito por un tiempo en mi auto sin embargo las minimas y maximas no se correpondian con las especificaciones del carro lancer mitsubishi.
asi que sera posible me regales el asm para ajustarlo o si puedes ayudarme te lo agradezco. lo que note es que me registra el doble de lo que especifica el fabricante
11/10/09 - 20:15:05 aliqasim from pakistan wrote: hola… puede cualquier cuerpo tell.that él trabajo correctamente. gracias.
11/10/09 - 20:17:05 aliqasim from pakistan wrote: quiero utilizar este circuito y el fichero del maleficio para mi proyecto puede cualquier cuerpo decirme es este 100% correcto… y dar por favor resultado correcto.
11/11/09 - 02:42:57 ZipZap from WA USA wrote: I'd like to build one of these to track the RPM on the motor in an electric car.  I'm new at this please excuse if very basic.  How is the Hex code entered?
Many Thanks
warpspeed15@excite.com
11/11/09 - 06:04:35 aliqasim from pakistan wrote: ZipZap. ESO NO ES un problema. el problema es ése. es eso es toda la fuente correcta. y el fichero del maleficio puede cuerpo decir que todo el circuito que diseña correctamente la ejecución en el Web site
gracias
11/11/09 - 08:47:31 aliqasim from pakistan wrote: can any body please tell me is this correct code and run perfectly .. reply me i need this .. thanks
11/11/09 - 08:52:34 José Pino wrote: Aliqasim:  If the microcontroller is programmed correctly and assembled as it should be,  it works. At least, it worked for me.
ZipZap: Open a new window on your browser and read: http://josepino.com/?aaa-getting-started
It explains how to program the PIC into them microcontroller.
11/11/09 - 09:33:12 aliqasim from pakistan wrote: José Pino... its run on ur side correctly.. because  after that i will assembled it .. so please quickly help me and tell me how to connect (6 To 13) pin's in 7segment display.. please completely explain Me .. i shall be thankful to me
11/11/09 - 11:08:13 aliqasim from pakistan wrote: is it can get the signal from car as well...
11/18/09 - 00:10:29 Sérgio Filho from Brasil wrote: Olá José.
Peguei este projeto para estudar, e consegui chegar ao código dele através de software "disasm". O problema é que não consigo simular o mesmo. Você poderia me ajudar no código obtido?
Abraços.

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