I am in the process of building an OSD for my home built CNC machine.

The circuit utilises CD40110BE up/down/counter/drivers directly driving dual 7 segment displays. The ICs have an up input and down input together with a reset. The ICs are cascaded and a signal at the first IC will increment up and down and to each of the other ICs in turn.

I have already built the circuit boards and am in the process of populating them. The complete project can be seen using the free version of CircuitMaker which I have found to be the best programme that i have come across for building circuits. The project is called 'CNC OSD' and anyway is free to use it or modify it as they see fit.

It is my intention to use the pulses from the BOB to the stepper drivers to increment and decrement the count on the OSD by using a microprocessor to send the pulses after first taking account of the microsteps for a given linear movement. I also intend to incorporate a handheld 'jogging' control

But, my problem is where is the best place to pick up the pulses from the BOB.

First of all, does anyone know whether the BOB sends a 'PULSE' and 'DIR' pulse simultaneously to reverse motion or just a 'DiR' pulse? Secondly; I am working on the jogger to send pulses back to the BOB using a variable speed oscillator (fast and slow) to provide the necessary pulses to move the machine backwards and forwards. Where is the best place to connect to the BOB that will not cause problems for the normal BOB output to the stepper drivers.

I am about to change my BOB for this one: https://www.ebay.co.uk/itm/5-axis-CN...kAAOSw4CFY3L55 and the system will be controlled from Mach3.

Any help would be appreciated especially from someone familiar with microprocessor control. I do not have any microprocessor experience and intend to use a Genie unit because it can be programmed through a flowchart system but any help with Arduino or similar would be a great help.