Mesa 5i25 encoder pins

Hi all,

I have a Mesa 5i25 (no daughter card) connected to my existing (parport) CNC controller.

I would like to add a spindle rpm sensor, and just working out my options for connecting it to the 5i25.

Does anyone have the electrical specifications for the encoder pins? (A,B,INDEX)

Thanks

With standard firmware, all FPGA I/O pins are the same
inputs are LVTTL with 5V tolerance and 3.3K pullup resistors to 5V
(when the 5I25 is jumpered for 5V tolerant mode)

So you can directly connect a TTL level encoder to the 5I25

Thanks PCW.

I don't need quadrature encoding (3 pins) .. I wonder if it's possible just to monitor just the IDX pin for spindle RPM (e.g. 1 pulse/rpm on IDX, and A/B will be not connected)

LS wrote: I don't need quadrature encoding (3 pins) .. I wonder if it's possible just to monitor just the IDX pin for spindle RPM (e.g. 1 pulse/rpm on IDX, and A/B will be not connected)

You can use just the A-pin and set counter-mode to true. But that won't support spindle-synched motions.

For the sake of three bits of wire, why not connect everything?

I only have one reflective-optical-sensor on the spindle.

I'll be fine for this machine though, as it's just for returning the RPM on the spindle.

Once I get this up and running I'll have a go at using this to control the Spindle PWM.

In that case, connect to Phase A and set counter-mode true and velocity scale to 1.

You can set velocity scale to 1/60 to give rpm if you prefer.

Thank you.

I'll have a go at setting this up next week .. then I'll post my circuit and config.