tach output help

[kongo]

Trying to build a tach output for my megasquirt. I will be us using the fast idle pin. Wanted to know if anyone else used this pin for tach. Also can this circuit be built externally. http://msextra.com/doc/ms2extra/Gene.../LowVTacho.GIF

[CODE4]

MS1? You should be able to jumper the FIdle output to the appropriate pin on the processor for TachO use. You could also use a small protoboard and build a separate circuit too. Up to you.

[VelocitàPaola]

Originally Posted by kongo

Trying to build a tach output for my megasquirt. I will be us using the fast idle pin. Wanted to know if anyone else used this pin for tach. Also can this circuit be built externally. http://msextra.com/doc/ms2extra/Gene.../LowVTacho.GIF

Which board do you have (v2.2/v3.0/v3.57)? Like Dave asked, are you using MS1, MS2, or MS3? For MS1, the FIDLE pin on the processor can't generate a tach signal like it can with MS2/MS3. You would be better off using JS0, JS1, JS2, JS3, JS7, or pin 10 if you can. You could build the circuit externally, but it would be better to build it inside the enclosure.

[kongo]

Sorry about that. Took a chance an went with above diagram. In the proto area. Going from cpu pin js11, then built diagram going out to spr1. From spr1 to white wire under glove box. My tach works now. Decide to use F idle for cooling fans.

Side note ms2 ver 3

[VelocitàPaola]

Originally Posted by kongo

Sorry about that. Took a chance an went with above diagram. In the proto area. Going from cpu pin js11, then built diagram going out to spr1. From spr1 to white wire under glove box. My tach works now. Decide to use F idle for cooling fans.

Side note ms2 ver 3

For MS2/v3.0, it sounds like you got it all right.