Pin Order for I/O - can I change this ?

Hello,

I have a 5i22 and a 7i33 Mesa card - the drives I have dictate that I need to run 2 from the analog outputs of the 7i33 and 3 from the PWM outs of the 5i22

The way to go about this is to ask for 7 encoders and 7 PWM gens so as there are 3 left over after the 4 for the first connector (which goes to the 7i33) - effectively a bunch of pins on the first block are wasted...

At the moment its not so much a concern as I have GPIO to spare - but more of a hassle is why the pin outs of the PWM and encoder are staggered between axes - for instance:

13 - X PWM P
15 - Y PWM P
17 - X PWM D
19 - Y PWM D

...X and Y intermingled

I'd like all my X axis ins and outs to be clumped in order as follows

1 - XA (encoder in)
3 - XB (encoder in)
5 - XI (encoder in)
7 - X PWM P
9 - X PWM D
11 - X PWM E

then the same for Y and so on - it'd make the ribbon cables much neater

maybe I'm about to learn why it is the way it is ? - hopefully its easier than I think cabling all this stuff up ?

Is this a Mesa thing, a PnCConf thing ? an EMC thing ?

1:1

The PWM/encoder pinouts match Mesa 4 Axis daughter card pinouts (the 7I33 and the 2 and 4 axis HBridges), so for example you could drive 2 or 3 or even 4 7I33s from one 5I22.

The pinout is hardwired in the FPGA bitfile.So if you dont like the pinout, a new FPGA bitfile must be created. This is fairly simple, as only one file need be changed (the pinout file) and then a ~5 minute re-compilation

Thanks,

I'll look into that file but it might be more work that the alternative in that I dont think the pccconf graphic will know I've done that and I might be causing more problems than i'm solving (still a beginner!)

I can easily cobble together a custom pinout bit file for you but as you mention,
pnconf will not work with it. To use any bitfile not supported by pncconf you would need to directly edit the HAL file.

I would be nice if pncconf could read the info from the loaded bitfile (from the IDROM that specifies the pinout and numbers and types of modules) so it would work with any bitfile
not just the ones pncconf has built-in knowledge about.

I'll post this in the suggested functions for pncconf thread ...

Am I being ignorant of another easier solution if I reason that if the components of each axis were ganged together then ribbon cable runs would be easier to make - at least at the Mesa end, who knows what kind of switcheroo is going on at the drives. I guess instead of ganging them up I'd make them mirror the order of the drives input pins.

Maybe people terminate using a connection block where the switching from ribbon or twisted pair is done ? I'm just having trouble finding one cheap enough, the industrial websites that do this stuff tend to let prices go wild

Most of the existing pinouts are specifically made for compatibility with our daughtercards, not general purpose breakout boards, so they must match the way the our daughtercards are pinned out, Some of these pinouts like the 7I33 pinout are actually quite old, dating from the late 1980's when we made LM629 based ISA motion control cards.

That said its only a 5-10 minute exercise for me to make a new bitfile with a completely new pinout/set of module, with a more rational pinout for using the I/O directly or via a straight through breakout like the 7I42.

The only problem with this is that its not supported by pncconf (as pncconf only has knowledge of a small set of pinouts)

Hey Andy,

So those slot inside the IDC headers directly ??

I've been pondering 50 line ribbon and tearing it appropriately for each axis - thing is at the drive end they also use IDC headers, I have to spilt the ribbon individually then make sure I clamp it into the right female header pin thingy correctly - it'll work with care, but I'd rather learn the proper solution (lets hope its not expensive)