It's this enclosure/header -- Modice SE with the single 30-pin connector. http://www.cinch.com/products/modular-integrated-connector-enclosure/modice= -se-le/ The connector is in 3 rows of 10 pins. From one end to the other, the=20 columns (of 3 pins each) are: (a) 3 analog sensor inputs (b) 3 analog sensor inputs (c) 3 analog sensor inputs (d) 5V Power to sensors, spare pin, analog in (e) RS232 input and 2 digital inputs (f) RS232 output and 2 digital outputs (g) Digital I/O (slow) (h) +12V power, 2 ground pins (for higher total current) (j) 3 solenoid outputs (k) 2 motor outputs and 1 solenoid I'm considering using the spare pin to provide the ground line to the=20 sensors. Right now, because this is a revision of a previous system and=20 there have been a LOT of changes, pin functions are quite all over the=20 place and yet it all works fine still. I've had some issues with noise=20 on the RS232-level input previously, but shielded wire and a termination=20 resistor resolved that. After much agonizing, the customer is now=20 willing to re-do the wiring harness for this, and this is probably my=20 only chance to re-do it properly. Cheers, -Neil. On 8/26/2015 2:59 PM, Gary Crowell wrote: > Could you post a trial pinout? How many ground pins are you allowing? > > On Wed, Aug 26, 2015 at 10:27 AM, Neil wrote: > >> The connector is not changeable as it's an integral part of the >> enclosure. It's similar to an automotive enclosure ECU, though used for >> a different purpose here. >> >> Yes, I do have the power split at the connector already -- one branch >> goes to the motor/solenoid drivers, and the other goes to the 5V >> regulator which then splits into two paths -- one to the logic side and >> the other to power the motor/solenoid drivers. I'm reading up on >> ferrites to determine where to best add those. >> >> Cheers, >> -Neil. >> >> >> >> On 8/26/2015 12:04 PM, embedded systems wrote: >>> Neil, it's not about sampling and averaging, it's about decreasing the >>> impedance on the supply point of your inductive loads by using >> electrolytic >>> capacitors. You can keep the diode suppressors onboard, but very close = to >>> the power connector. >>> Usually you don't use the same connector for power, communications and >>> analog signals, this is against of any good practice rule. You can do i= t >>> but it's your choice. >>> >>> You do not need other regulator for inductive loads, just as you split >> the >>> ground, split the power. Arrange the paths of your currents radially, s= o >>> the digital/analog current will not flow through the same path as power >>> current. >>> >>> On Wed, Aug 26, 2015 at 6:12 PM, Neil wrote: >>> >>>> The connector is polarized, so that's not an issue. A lot has to happ= en >>>> simultaneously -- analog sampling, solenoid driving, etc. But yes I am >>>> averaging and filtering the analog signals -- up to 128 samples on som= e >>>> of the signals that don't change rapidly. My concern is more with the >>>> digital serial signals getting corrupted by the higher-voltage signals= .. >>>> >>>> I do have one signal] which has a pull-up and that's a shutoff-switch >>>> input (ie: tells the system to shut off completely). I'll have to look >>>> into keeping this further away. >>>> >>>> I had not thought about ferrites but I'll look into those. I did find >>>> this neat doc on EMI which I'm still going through, and it too mention= s >>>> ferrites... >>>> http://www.ti.com/lit/an/szza009/szza009.pdf >>>> >>>> None of the serial is differential -- one is RS232 (actual RS232 level >>>> from a MAX232) with error checking. Another is also RS232, with no >>>> error checking, but that comes from a different system so I don't have >>>> much control over that. The third serial data-stream is a 5V level >>>> custom protocol. It does have a checksum in both directions. >>>> >>>> I'm confused about using 2 grounds yet merging them where they enter t= he >>>> board. Wouldn't that mix any noise generated by the motor side onto t= he >>>> logic-side? >>>> >>>> Cheers, >>>> -Neil. >>>> >>>> >>>> On 8/26/2015 3:07 AM, Jesse Lackey wrote: >>>>> Hummm.... neat question. >>>>> >>>>> One aside: if the connector isn't polarized, you could use >> strategically >>>>> place the spare pin such that if the connector is inserted backward a= nd >>>>> power applied, the +12V goes to this unused pin, and the user gets >>>>> nothing happening vs. smoke. >>>>> >>>>> Can you arrange things such that you aren't sampling the analog senso= rs >>>>> while motors are running (or starting/stopping), or solenoids >> switching? >>>>> Or maybe at least take an average over time to minimize bad data= .. >>>>> >>>>> Digital I/O ... it would be best if all signals are driven, i.e. not >>>>> have pullups, for better noise immunity. Not sure how much it matter= s. >>>>> >>>>> You could use that spare pin for a ground for digital and/or analog, >> and >>>>> have the digital and/or analog ground therefore be separate from the >>>>> rest, and connect the grounds together where the power comes in from >>>>> whatever is plugged into this and making the +12V. That said, I have >>>>> seen cases where the best performance was to use the same ground all >>>> over. >>>>> A ferrite on the +12V @ the connector would be a polite thing to do, >>>>> maybe on the motor as well. They're cheap. >>>>> >>>>> I assume the serial is differential (rs485?). Doing it packetized wi= th >>>>> a CRC and having both ends of the communication keep count of how man= y >>>>> packets are damaged is a good way to monitor signal integrity. i.e. = do >>>>> things all command/response style and be able to ask that count to >>>>> determine % damaged. >>>>> >>>>> I look forward to this thread! >>>>> J >>>>> >>>>> >>>>> >>>>> 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 signa= l >>>>>> pairs, and a number of analog sensor signals coming in. The catch i= s >>>>>> 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 th= at >>>>>> 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 t= he >>>>>> 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 sid= e >> 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 >>>> >> -- >> 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 .