Common ground

I designed a pcb in this way for nano, I made all of the common ground. Do you think this is the right method? Thanks. My pcb design is attached

Grounding is OK.

Curious about the part locations and the trace going around the upper sensor ground.

I would:

  1. add pads for capacitors at the power for the sensors.

  2. add pads for a series resistor and capacitor to ground for each sensor signal.

  3. add pads for some of the Nano's input and output pins. If analog input I would add the same as 2) above.

Grounding is correct. You must have a common ground

Rip up all those traces and redraw them so they're all straight vertical/horizontal or 45-degree angles if anyone other than you is going to see the PCB. People will negatively judge you based on that routing - it makes it clear that you're inexperienced and/or that you threw the design together and/or take no pride in your work.

Agree with JohnRob about adding pads (or holes) for a cap between power and ground at each sensor connection. I'd also put an additional cap on the external power input.

I have generally not found the series resistor and cap to be necessary for analog sensors, but adding the pads (or holes) for a cap on the analog signal lines is free - if you find you don't need it, no need to install a cap. But if you didn't put the pads there, and discovered that there was more noise than you wanted on the analog lines, you'd be left tacking the cap onto the bottom of the connector pins or something. This is only appropriate for analog lines, of course.

If any of the sensors are I2C, leave pads for pullup resistors if the I2C sensor being used doesn't have appropriate pullups on board.

Are those mounting holes in the places they are for a reason? The one in the middle in particular looks like you just put it where it looked like it would be easiest to fit, instead of in a place that makes sense. When in doubt, put them in the corners, and a rational distance apart (it's easier to measure 1.8inches or 1.75 inches, vs 1.7159 inches or something, and weird distances leave a bad impression, like sloppy routing as noted above). But maybe you have to match existing holes, in which case disregard this comment.

Why 0.2" spacing on the holes for some of the sensors? Are you matching an existing connector? If not, unless you need bigger connectors to handle the current, I'd use 0.1" pitch connectors. (for wiring up sensors, I usually use 0.1" pitch JST connectors, since they're not as tall as dupont connectors, and you can get connectors with wires dangling from them on ebay (so you don't have to crimp your own connectors, which is a huge pain in the ass)

JohnRob:
Grounding is OK.

Curious about the part locations and the trace going around the upper sensor ground.

I would:

  1. add pads for capacitors at the power for the sensors.

  2. add pads for a series resistor and capacitor to ground for each sensor signal.

  3. add pads for some of the Nano’s input and output pins. If analog input I would add the same as 2) above.

firstly, sorry for the first picture… i am quite amateur about it. Why should I add capacitor? (My schematic is attached)

Thanks,

DrAzzy:
Grounding is correct. You must have a common ground

Rip up all those traces and redraw them so they’re all straight vertical/horizontal or 45-degree angles if anyone other than you is going to see the PCB. People will negatively judge you based on that routing - it makes it clear that you’re inexperienced and/or that you threw the design together and/or take no pride in your work.

Agree with JohnRob about adding pads (or holes) for a cap between power and ground at each sensor connection. I’d also put an additional cap on the external power input.

I have generally not found the series resistor and cap to be necessary for analog sensors, but adding the pads (or holes) for a cap on the analog signal lines is free - if you find you don’t need it, no need to install a cap. But if you didn’t put the pads there, and discovered that there was more noise than you wanted on the analog lines, you’d be left tacking the cap onto the bottom of the connector pins or something. This is only appropriate for analog lines, of course.

If any of the sensors are I2C, leave pads for pullup resistors if the I2C sensor being used doesn’t have appropriate pullups on board.

Are those mounting holes in the places they are for a reason? The one in the middle in particular looks like you just put it where it looked like it would be easiest to fit, instead of in a place that makes sense. When in doubt, put them in the corners, and a rational distance apart (it’s easier to measure 1.8inches or 1.75 inches, vs 1.7159 inches or something, and weird distances leave a bad impression, like sloppy routing as noted above). But maybe you have to match existing holes, in which case disregard this comment.

Why 0.2" spacing on the holes for some of the sensors? Are you matching an existing connector? If not, unless you need bigger connectors to handle the current, I’d use 0.1" pitch connectors. (for wiring up sensors, I usually use 0.1" pitch JST connectors, since they’re not as tall as dupont connectors, and you can get connectors with wires dangling from them on ebay (so you don’t have to crimp your own connectors, which is a huge pain in the ass)

yes i guess i need to redraw traces, i used screw terminal but i will change 0.1" pitch connectors.

Thanks,

Is this single-sided?
Why yellow?
red means topside (component-side) copper, blue means bottomside.

MarkT:
Is this single-sided?
Why yellow?
red means topside (component-side) copper, blue means bottomside.

Double sided.
i have no idea :), i am amateur. I used fritzing.

Ah. So what does yellow mean? Normally you can have groundplane on one side and traces on
the other for a simple circuit.

meaning of yellow ground plane.

On Eagle, the program most of us use, the top copper layer is by default shown in red, the bottom in blue. This is I think the case in some other programs - but not all. Presumably the program you’re using doesn’t use this convention (or you generated it from a board previewer or something, which didn’t use those colors). I think people are being silly to point it out (or maybe you chose yellow solder mask so the preview was yellow? - as an aside, I always use the yellow soldermask option for an experimental design, because it’s easiest to see where the traces are when you’re debugging it and are like "Wait, what pin did I connect that to again? Red is also good for this - black and white on the other hand almost completely obscure the traces).

Cap would go from the analog signal line to ground - if you find that you’re picking up more noise than you’d like, you can put a cap there to smooth it out. The correct value of this cap, if you need it (I almost never use them - but you’ve got acres of space on that board so you might as well leave a space for them), depends on the signal you’re measuring (ie, how fast it changes, impedance of the thing it’s coming from, how bad the noise is etc).

DrAzzy:
On Eagle, the program most of us use, the top copper layer is by default shown in red, the bottom in blue. This is I think the case in some other programs - but not all.

Those were the standard colours from the days of hand-layout using transparent coloured tape onto acetate,
predates CAD