Gnd

OutIn

U57805

C2

22uF

C1

22uF

RA2/AN2/VREF1

RA3/AN3/CMP12

RA4/T0KI/CMP23

RA5/*MCLR/VPP4

RB0/INT6

RB1/RX/DT7

RB2/TX/CK8

RB3/CCP19

RB4/PGM 10

RB5 11

RB6/T1OSO/T1CKI/PGC 12

RB7/T1OSI/PGD 13

RA6/OSC2/CKOOUT 15

RA7/OSC1/CKIN 16

RA0/AN0 17

RA1/AN1 18 U4

16F648A

R5

120

R6

R7

R8

R9

R10

R11

R12

120

R3

1k

R2

1k

R1

1k

12VDC

S1

C3

10nF

http://www.randomwisdom.com/2007/10/digital-speedometer-using-pic-microcontroller/

Programming implementation and more information available at:

R4

100k

Vcc out

Vcc

Button

S2A

Speedo Reed Switch

R13

Vcc

C4

10nF

Stock ECUs usually power the switch with R13,

but the capacitor is necessary to prevent noise.

You could also use a Hall sensor or any 0-5V signal.

Note: These 7-segment resistors can be connected to processor in any order.

Q1

NPN

Q2

NPN

Q3

NPN

CC1

F2

G3

E4

D5

CC6

DP7

C8

B9

A10

U1

7SEGCC

CC1

F2

G3

E4

D5

CC6

DP7

C8

B9

A10

U2

7SEGCC

CC1

F2

G3

E4

D5

CC6

DP7

C8

B9

A10

U3

7SEGCC

Title

Author

File

Revision

Document

Date Sheets

PIC16F648A Digital Speedometer

Jeffrey Hiner

C:\speedometer\speedo.dsn

1.01 October 3, 2008 1 of 1