Moteino M0 Protoboard?

[adam.g]

Hi Felix,

I've really been enjoying familiarizing myself with my new Moteino M0s and have been having some great success with the RFM95 LoRa radios.

Up until now I've been just prototyping everything up on a breadboard, which got me to thinking about how nice it would be to have a stackable protoboard for the Moteino M0. Have you given any thought to offering them?

They've come in super handy for my Adafruit Feather boards, but because they have a specific pin configuration, they aren't compatible with the Moteino.

Cheers,
Adam

[Felix]

Nice to hear you're having success with the M0!
The proto could be easily made, yes, and a nice suggestion, something I will consider (if I ever get some spare time!).
Are you looking for something that's exactly flush with the M0?
Since I designed it to be breadboard friendly (ie headers spaced at 0.1" multiples) you could use it with a standard protoboard like the 3x7cm.
Then the M0 could be stacked ontop.

[adam.g]

Hi Felix,

Thanks for the reply!

I've worked a lot with the Adafruit Feather doublers, triplers and protoboards and they've been a great way to stack and modularize my projects. As I often 3D print enclosures for my projects, it's important that they be flush when they stack. If you ever get the time it could be a great way to add even more modularity to the Moteino M0.

Speaking of modularity, are there any plans in the works for new M0 breakout boards? It'd be great to see an external RTC breakout board. I have to add a DS3231SN to every one of my projects that's deployed in the Arctic because of the lack of temperature compensation or battery backup with the M0's internal RTC.

Cheers!
Adam

[TomWS]

Speaking of modularity, are there any plans in the works for new M0 breakout boards? It'd be great to see an external RTC breakout board. I have to add a DS3231SN to every one of my projects that's deployed in the Arctic because of the lack of temperature compensation or battery backup with the M0's internal RTC.

That's a great RTC.  I've used the DS3232 on a number of projects and I'm never disappointed.  A smaller package would be nice, but I guess that isn't possible with the integrated TCXO and crystal.

Tom

[Felix]

Speaking of modularity, are there any plans in the works for new M0 breakout boards? It'd be great to see an external RTC breakout board. I have to add a DS3231SN to every one of my projects that's deployed in the Arctic because of the lack of temperature compensation or battery backup with the M0's internal RTC.

Always looking for ideas and suggestions. If something makes a lot of sense then I invest the time and funds to make it happen.
Are there any resources I could look at to get a quick start on such a new M0 breakout?
Do you think it would make sense to continue to make any such M0 breakouts with the same castellated mounts in addition to the standard header pin holes?

[adam.g]

Hi Felix,

I try not think about how much time I've spent reading the DS3231 datasheet and working with related libraries for both AVR and ARM processors, but I can definitely provide you with some resources! I've considered designing my own PCB for some time now.

DS3231SN Datasheet
The circuit is relatively simple, with the most common configuration including 10k resistors on the I2C SCL/SDA lines, a CR1220 coin cell battery tied to the battery backup pin, as well as 1uF decoupling capacitor. I've provided a few examples below that link directly to the schematic downloads.
https://www.mouser.ca/datasheet/2/256/DS3231-1513891.pdf
 
Adafruit DS3231 Precision RTC Breakout
Unfortunately, Adafruit uses the commercial version (DS3231S) instead of the industrial version (DS3231SN) of the IC, which is able to handle -40°C to +85°C. In the past I've either had to desolder the IC from their breakout board or use a SOIC-16 breakout and a separate CR1220 battery breakout.
https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/downloads

Adafruit DS3231 Precision RTC FeatherWing
Having recently moved over to the Feather ecosystem, this became my new favourite stackable RTC, but again they're still using the commercial version of the IC that is only rated 0 to +70°C. Sufficed to say, I've gotten pretty good at desoldering SOIC-16 ICs.
https://learn.adafruit.com/ds3231-precision-rtc-featherwing/downloads

Jeelabs Precision RTC Plug
Here is just an example of a simple design with the battery and IC on the same side of the board.
https://www.digitalsmarties.net/products/precision-rtc-plug
https://jeelabs.net/projects/hardware/wiki/precision_rtc_plug

Regarding the castellated mounts, I believe that they definitely come in handy when adding only a single breakout board to the M0, such as the microSD or BME280 boards. However, if you plan on adding several additional components, they become less important as you may need to find a different solution for mounting everything together. It's certainly application specific, but always nice to have the option. Do they add much in the way of complexity or extra cost to the boards?

Happy to help if you have any additional questions!

Cheers,
Adam

[Felix]

Thanks, nice primer info!
I love maxim parts, but not their prices.
Weird how this SOIC-16 part has the bottom half pins unconnected to anything. Their SOIC-8 variants do not have the TCXO feature.

Do they add much in the way of complexity or extra cost to the boards?

Castellations add to the cost especially if you're ordering many panels it becomes a significant increase. Now that I bought into this system for the M0 it's hard to undo ;-)

So I will keep this in mind, do you think you can buy the first 100 so I can justify getting on with it?