Neil, I've took a look at connector drawings. this connector seems to me OK for multiple signals. However, in the same group of three, I will consider analog signal + return analog ground of each signal. There is no current specification for the connector. Inside the box use ferrite in series on the aggressors circuits and uninterrupted PCB ground around analog signals. You need revision zero of the box for your answers. best luck! Vasile On Tue, Sep 1, 2015 at 6:01 AM, Neil wrote: > Vasile, > > The solenoid and motor signals are being generated in the box, but will > have it's own cable branch. So I'm more concerned about those signals > inside the box inducing noise on the low-level serial signals inside the > box. > > I'm still learning about ferrites to select something appropriate to > isolate noise inside the box. > > Cheers, > -Neil. > > > On 8/27/2015 2:11 AM, embedded systems wrote: > > This is the major problem (the cables) when use a single connector for > > power, analog and digital signals. > > The power cables and digital wires are aggressors for the analog signal= s > > carried by wires, even if using shielded cables. > > > > So in such system (but not only) the major concern is to reject the noi= se > > induced in the analog paths by the digital and power signals, the last > > being the most aggressive. > > As long a bunch of cables will go from the same connector to your > external > > devices, is likely you'll have plenty noise induced by solenoids or > motors. > > > > Once you can separate the cable groups, the noise may be (not *is* for > > sure) smaller. Every group of cable should have it's own local ground, > but > > finally you'll have just one ground. The trick is to avoid the passing = of > > the noise from one ground to the other as well from one power supply to > the > > other. > > > > Vasile > > > > On Thu, Aug 27, 2015 at 4:15 AM, wrote: > > > >> Hi Neil - > >> > >> I'd be more concerned with the bundling of the cable - do the differen= t > >> wires bundle together in a single cable? Do they go to one destination= ? > How > >> long is it? Any shielding? Is this a ribbon/IDC connector or > >> individual/crimped? Is there another ground path (chassis)? > >> > >> Also, how much resolution do you expect from your analog signals (I > assume > >> you will digitize). What is the source impedance? Amplitude? How many? > >> > >> I personally would associate any spare ground with the analog signals. > >> > >> Good luck! > >> Stephen > >> > >> > >> > >> -----Original Message----- > >> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On > Behalf > >> Of Neil > >> Sent: Wednesday, 26 August 2015 4:55 AM > >> To: Microcontroller discussion list - Public. > >> Subject: [EE] Best practices for reducing noise > >> > >> 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 handl= e > 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 wi= th > >> 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 > >> > >> -- > >> 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 .