Kflop to Kstep connection

[steveastrouk]

I have a Kstep board wired to a Kflop via JP36 on the Kstep, and powering the Kflop over JP36 via the JR1 connector on Kstep. I have removed the USB 5V power jumper, J3 on Kflop, and checked that jp34 and 35 are present on Kstep. My intention is to run the unit with a PC power supply for the time being.

When I do this Kflop does not ennumerate when I plug in USB. In fact, I can only make it work by removing JP34 and 35 on Kstep and powering the 5V with USB. I have checked 5V is reaching Kstep on the JR1 lines, and by testing on Kstep J33 pin 25 and 26.

WITH USB 5+ applied, then Kflop ennumerates, and I can run my drives. To do this, I have removed Kstep jp34 and jp 35, and put J3 back on Kflop Its no great problem to link up another 5V supply, because I don't think isolation is a big issue for me.

I would just like to understand where I am going wrong ?

Steve

[TomKerekes]

Hi Steve,

Strange. Powering KFLOP from KStep in that way should be possible.

When doing so does KFLOP boot up and flash the LEDs?

Please check if 5V exists on KFLOP JR1.

Please check if the ribbon cable between KFLOP and KStep is inserted completely and there are no signs of damage. You might also check for continuity of pins 23-26.

[steveastrouk]

Thanks Tom,

Kflop Leds do NOT light without it being USB powered and Kstep isolated. If I run with USB power Kflop and Kstep work fine, except I can't access the optoisolated Inputs I have set up.

The other tests I can report on when I am back in the office in the morning.

I appreciate the fast reply.

Steve

[steveastrouk]

Initially there was nothing on Kflop JR1, so I pushed everything home, and still nothing. Then I seem to have twisted the PCB slightly, because the Kflop LEDs flickered into life in the correct power configuration and everything seems stable.

Right now, I don't really trust it, but I can continue. I have a presentation to the company president in the morning, in which the thing I am driving with kflop and step has the starring role.

[TomKerekes]

Hi Steve,

That sounds like a faulty GND connection through the ribbon cable (pins 25 and 26). I think that would explain why the opto inputs don't register in KFLOP even with separate supplies. Please inspect it carefully to see if the connector is crimped on the cable properly.