Prototyping with SCM20100E

Does anyone have a suggestion as to what would be a suitable protopying option for the SCM20100E?
I’d need some proto board on which I can solder the SCM20100E and at least a USB connector (perhaps the usb connector on a breakout board). Any suggestions for such prototyping boards?

Looking forward to any suggestions …

The SCM20100E seems to have a pitch of 0.05"

Here is an Eagle library file from Darko.

Thank you, that helps.
I also found the pin out here: SITCore System on Modules
Further I found a 50mil (1.27mm) through-hole protoboard:
I think I can solder the SOM on this and start from there …
So now I’ll have to wait for the components to arrive.

If you have PCB design software, a 100x100 board from JLCPCB is about $4 plus shipping and 2 days manufacture. By far the best way to prototype as you can ensure that USB tracks use differential pairing and should be easier to solder a SUB connector too.


TBH, I am trying to avoid doing pcb design. I’ve done it in the past. But I learned …
A) I’m not good at it.
B) it costs me sooo much time. So many details …
C) I need the time for software and customer.

So, I hope it suffices to limit my hardware efforts to some prototyping by soldering stuff together on a breadboard. And when things work, I’ve had some PCB boards made in the past with the help of an engineer / pcb designer. The results were really OK, both technical and commercial. More complex stuff I need help from experts from the ground up ;-(

Is it possible to connect a USB-C connector to the SCM20100E and use it for programming the device?

Like this one:

Pins SCM20100E:

Yes, that should work. I now use USB Type C for all debug connections and just use the USB 2 interface connections.

Super, thanks!

And to make this work, what connections would be required? Just brainstorming here, any expert feedback is welcome…

As inspiration I looked at the FEZ Duino schematics:



Here is the connection table:

USB-C connector                     <-> SCM20100E
------------------                  --- -------------
VBUS   <-> STPS140A    
       <-> LDO (LM1117MP-3.3)       <-> 3V3 (pin 32)
GND                                 <-> GND2 (pin 31)
CC1    <-> R1 (5.1K)                <-> GND2 (pin 31)
D-                                  <-> USBC_N (pin 45)
D+                                  <-> USBC_P (pin 46)
CC2    <-> R2 (5.1K)                <-> GND2 (pin 31)

And here for each connection the reasoning …

The VBUS provides +5V. In order to safely connect this to +3V3 pin 32, it must be regulated.
On the FEZ Duino this is done like in the 2 images above. First through the STPS140A and then using a LM1117MP-3.3. I assume the STPS140A provides extra safety for spikes / voltage reversals?
Since the SCM20100E does not have a +5V pin somewhere, the FEZ Duino setup is followed. As a result, a 3V3 is supplied to the SCM20100E on pin 32.

CC1 and CC2
On the FEZ Duino the CC1 and CC2 pins of the USB-C connector are each connected to a 5.1K resistor and then to GND.
This is a safe way of signalling to the USB host that nothing is going to be charged here? CC1 and CC2 are charging signals right?
These signals will be routed as in the SCM20100E prototype setup. They will go through 5.1K resistor to GND. They will not go into SCM20100E.

D- and D+
The D lines go directly to pin 45 and pin 46 of SCM20100E. On the schematics of the SCM20100E is see the following:
This means we have a resistor between the pin and the chip on board already.
So it is safe to connect directly from the USB connector to PIN 45 and 46?

Again … feedback welcome!

The STPS140A is there to prevent the power from back feeding to the USB device that is connected when you use a bench or other power supply to power the board.

The resistors were mentioned before in another pos and should be documented with the modules etc. GHI should confirm their use if the documents don’t already indicate this. I think for the SOM they are included on the SOM but for the IC options, you need them.

The USB resistors are not needed but we include with the SoM anyway

Thank you. That makes it clear.

Hummm, OK!

Components arrived today. So unpacking the FEZ duino … sofar so good. Blinky works … first impressions are really good. The board looks absolute professional made… looking forward to next steps!

And their online support staff is great!


Glad you love it

Here is my first kicad schematic. Its for a carrier board for the SCM20100E module. My intent is to assemble it and connect this to my dev PC (which acts as the USB host, with VS2019), upload firmware, upload and debug an app and ultimately simply run the app on the SCM20100E.

Will this work? Any feedback on the schematic? Feedback is appreciated!

Wrong usb port for debugging, use usb client (USBC_P, USBC_N)
take a look at the dev board schematic

you can also if you want put a small chip led so you know you have power
Screenshot 2020-10-22 193018

I’m almost done with my schematic, as soon as i find a way to measure external voltage without using an analog pin, as i have none left that are free. :laughing:

Haaa … good catch. I’ll change USB pins! Thank you for your input!

I like the powerled idea, and a custom led? Like so?

Does it contain other mistakes, or any further ideas?

Check your pin names, you have multiple PE3
Connect pins 1,31 to GND
Connect pins 2,3 to +3.3v

OK, wow, really good. I forgot I did not know how to handle 1, 2 and 3 when I was making the symbol. I think I made the changes you mentioned. Many thanks for your sharp eye!