The connector is not changeable as it's an integral part of the=20 enclosure. It's similar to an automotive enclosure ECU, though used for=20 a different purpose here. Yes, I do have the power split at the connector already -- one branch=20 goes to the motor/solenoid drivers, and the other goes to the 5V=20 regulator which then splits into two paths -- one to the logic side and=20 the other to power the motor/solenoid drivers. I'm reading up on=20 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 electrolyt= ic > 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 it > but it's your choice. > > You do not need other regulator for inductive loads, just as you split th= e > ground, split the power. Arrange the paths of your currents radially, so > 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 happen >> simultaneously -- analog sampling, solenoid driving, etc. But yes I am >> averaging and filtering the analog signals -- up to 128 samples on some >> 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 mentions >> 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 the >> board. Wouldn't that mix any noise generated by the motor side onto the >> 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 strategicall= y >>> place the spare pin such that if the connector is inserted backward and >>> 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 sensors >>> 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 matters. >>> >>> You could use that spare pin for a ground for digital and/or analog, an= d >>> 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 with >>> a CRC and having both ends of the communication keep count of how many >>> 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 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 kep= t >>>> 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 .