Vasile, The connector is not changeable -- it's all on one connector as built=20 into the enclosure. This is why I'm asking what's the best way to=20 allocate the signals on this one connector. I do have diode suppressors for the reverse spikes, but those on the=20 board. Currently those are right at the transistors, but I'm thinking I=20 can move them closer to the connector. I'd like to avoid moving them=20 outside the box, but I can do that if necessary. W.r.t. splitting the power supply -- most of the 5V is being used by the=20 PICs and other logic/analog side, but the motor and solenoid driver=20 chips also use that 5V. Those then switch the 12V power on/off to=20 control the motors and solenoids. Are you suggesting that even though=20 it's not switching 5V on/off, it would generate enough noise to warrant=20 splitting 5V power supply? I can do that relatively easily, by adding a=20 linear 5V regulator to the motor/solenoid driver side. Cheers, -Neil. On 8/26/2015 7:40 AM, embedded systems wrote: > First of all, you have to separe the digital signals in one connector and > the power signals in the other connector. > This is the first rule. > > If you have analog signals as well, use the third connector, or just put > them in the opposite corners of the digital connector with plenty ground > between them. > > Power connector should have at least one large capacitor onboard near it, > but I suggest to mount one for every strong current (ie. solenoid, motor)= .. > There should not be any reverse spikes on your board, use diode suppresso= r > mounted on the solenoid coil ends and not on the board. > > You may split the ground, but this is not enough if you don't split as we= ll > the power supply lines, even it comes from the same power supply. > > best luck, > Vasile > > On Tue, Aug 25, 2015 at 9:55 PM, Neil wrote: > >> I'm trying to figure out how best to allocate connector pins for a >> mixed-signal board. The system has high-current, high-voltage, >> repeated-switching signals (motors and solenoids), serial data signal >> pairs, and a number of analog sensor signals coming in. The catch is >> that this board has only one 30-pin connector (3 rows of 10 pins each). >> >> Currently, I have, in order starting from one end towards the other: >> - Motor + and - (12V, 6A max) >> - Solenoids (up to 4A, but with reverse spikes will see 30V+) >> - Power & ground (12V) >> - Serial signals (3 pairs) >> - Digital I/O >> - Analog sensor signals >> >> The PCB has the motor and solenoid drivers on one side of the board, >> power supply in the middle (but off towards the back), and 2 PICs that >> handle all the logic near the other side. The analog circuitry is kept >> really short and off in one corner of the board nearest the end of the >> connector with those signals. >> >> So what I'm wondering is: >> - Is there a better way to organize the signals on the connector? >> - I have one spare pin -- should I run a separate logic ground? >> - If so, where would I connect these on the board (or wouldn't this >> cause a ground loop)? >> - If I do or don't, should I split the ground plane so the logic side is >> separate from the motor/solenoid side? >> - Anything else I should do? >> >> Cheers, >> -Neil. >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .