spindle speed pulse input 7i77

Hi!
I´m converting an old Terco CNC45 milling machine that has servo motors. Therefore i´m using Mesa 6i25 and 7i77 for the analog signals and encoder input from axis.
For the spindle i have removed the old boring brushed dc-motor and replaced with an brushless DC that i drive with a RC-speed controller. I´m using an Atmega microprocessor to read analog voltage from 7i77 and output corresponding servo pulse to the speed controller. So far all axis and output to spindle works like intended.
From the spindle speed controller i have a speed pulse output that i want to connect to linuxcnc so that i can make a PID regulator for spindle speed. I think it is 1 pulse/n. I have tried to connect the pulse to encoder input to linuxcnc, both A in and index, but linux cnc expects a real resolver so i don´t get any speed counting.
Is there any way that i can input an simple pulse signal to 7i77? Just to count unsigned speed

Thanks in advance!
Br Andreas

If it is one pulse/rev you would connect it to both the A and I inputs, and you need to set the encoder counter mode to true (setp hm2_6i25.0.encoder.NN.counter-mode 1).

If you set the spindle encoder counter to step/dir mode (1) rather than quadrature mode (0)
it should work with the pulse connected to the "A" pin

Great! Thanks! Will try this asap.
Maybe i´ll buy an encoder for the spindle in the future if i will have a need for more accurate spindle positioning or if its hard to make the regulator work good. But i guess that my main delay in the system is the rc-servo that´s updating every 20ms. As long as i run the spindle over 3000rpm, one pulse per revolution will not be the limiting factor.

Thanks again, great support!