rover wrote:Does anybody know if it is possible to use the driver without 2 7i48 cards connected ?,
As far as I know both Stepconf and the Hostmot2 driver are completely unaware about whether there is a card connected to any output port.
However, a bitfile can only put the functional pins on particular physical pins. These pins can either have their primary function, or have that function disabled and be used for general purpose digital IO.
So, if you had a bitfile which created 72 PWM outputs on 3 ports, and you set up the LinuxCNC driver to only load 36 of them, then ports 0 would be all-PWM, port 1 would have PWM on pins 0 to 11, and GPIO on pins 12 to 23, and the other port of the 5i20 would be all GPIO.
You can see the pin assignment for that firmware in the vhd file that it is compield from here:
git.linuxcnc.org/gitweb?p=hostmot2-firmw...abfd863298c67a2f618f
(line 109 onwards). It should also be available as a .PIN file somewhere on your PC.
You can see that that firmware is intended for 2 x 7i48 and one connector of GPIO. Ports 1 and 2 have the 7i48pinout, and port 3 is left undefined.
I don't think that there are any firmwares that support both the 7i48 and the 7i33. It is probably possible to build one, and there are a number of us who are able to do that. (including, of course, Mesa electronics).
However, it might be better to swap the 2 x 7i33 for 1 x 7i48, then you have a connector of GPIO for other applications.