💬 Sensebender Micro mk2

[openhardware.io]

https://www.openhardware.io/view/283/Sensebender-Micro-mk2

[Ptibu]

Hello, tbowmo
I'm new to mysensors and home automation and this board is exactly what I was looking for, great job !
Have you received prototypes? Do you plan to sell it ?
And what about using SAML instead of SAMD for ULP nodes? Would it be supported by Mysensors?
Thank you for sharing!

[beaugunderson]

"Temperature / Humidity sensor Si7021" is listed as an enhancement but the mk1 had the same sensor correct?

[tbowmo]

@beaugunderson

Right, my mistake.. both flash and si7021 is borrowed from mk1..

@Ptibu
I haven't ordered any prototype pcb yet. I'm trying to keep prices down, and SAML is still pretty expensive, compared to SAMD.

[Ptibu]

@tbowmo
Another big advantage of the SAML over the SAMD is the embedded AES core. It would allow strong crypto for both comm & data encryption (at MCU level, not radio) and authentication (ex: AES based CMAC). In this case, the ATSHA is not needed anymore for auth but it will break compatibility with existing ATSHA based boards (unless implementing SHA256 in SW).
For what I can see, cost for SAML is about the same than SAMD + ATSHA (+/- 0.5€).

For new (secured) mysensors networks, SAML would have nice advantages with comparable price (+dev efforts of course).

[scalz]

@Ptibu
I'm also using some custom atsamd boards on my side. I looked a while ago at SAML. They have some some common points, but if i remember SAML datasheet, it's not completely the same, especially for low power modes, additional features etc.. Is SAML Arduino compatible now? i'm just curious, i don't really need it as there are already so much other great mcu or complete module

[Cliff Karlsson]

Is there any site where you can upload the pcb+bom and have all the components (maybe not radio and pinheaders) soldered before they send the pcb?

[Ptibu]

@scalz said:

Is SAML Arduino compatible now?

Not yet. but it is WIP
https://github.com/arduino/arduino-builder/issues/176#issuecomment-269110984

@Cliff-Karlsson said:

Is there any site where you can upload the pcb+bom and have all the components (maybe not radio and pinheaders) soldered before they send the pcb?

It is called PCBA service. dirtypcbs and itead have such services.
Got price estimation from itead few weeks ago for this board: about 550$ / 10 boards, including PCD ~100$, stencil ~60$, components ~219$ and assembly ~150$)

[tbowmo]

@Cliff-Karlsson @Ptibu

You can order the board from our partner itead studio here, with all SMD components mounted. You need to add radio / ethernet module yourself.

[tbowmo]

@Ptibu

Just checked mouser prices, for 100 units:

ATSAML21E18B-AUT : 519,0$

ATSAMD20E18A-AUT : 298,0$
ATSHA204A-STUCZ-T : 83,7$
total : 381,7$

price difference: 137,3$ for 100 boards, or 1.37$ per board. So we can still save a couple of bucks by using atsamd + atsha204

[Ptibu]

@tbowmo OK, for 100 pieces, it makes a huge difference, sorry.
And glad to see the gateway available, good work !

[tbowmo]

@Ptibu

I'm always looking at larger quantities when designing boards :).. Specially when designing the sensebender boards, if we can lower the price just a little it means cheaper boards for the community, or a bit more contribution to the site maintenance etc.

[bjornhallberg]

Any progress on the mk2?

[tbowmo]

@bjornhallberg

I've got the first prototype pcbs for it.. So just need to get components and assemble the first sample. However, the wife thinks that a new chicken coop (which will be filled with sensors :D) , and various other projects, have higher priority :).

[lafleur]

Is this board using the RFM69HCW footprint so that one could also use an RFM95??
If not, please consider this change and you might want to consider as an option for DIO-1 connected to an I/O pin on the CPU.. (this would also make it compatible with LoRaWan network)

Thanks

[tbowmo]

@lafleur

I used the standard RFM69W footprint at the moment. This is because I do not need the high power variant, that the RFM69HCW is (it is more power hungry as well)

Things can still change...

[lafleur]

Both the RFM69HC and RFM69HCW are available in the smaller package.... again, this would allow RFM95 to be used.

Thanks...

[0_1496601875842_RFM69HC_DataSheet_v1.1.pdf](/assets/uploads/files/1496601877634-rfm69hc_datasheet_v1.1.pdf) 

[tbowmo]

@lafleur but doesn't the H denote a high power output device? Which means higher power consumption.

[lafleur]

Yes, The H = High Power version, C = Compact version 16x16mm pkg, vis 16x19mm pkg

My error, RFM69CW and RFM69HCW are available, also note that if you do not use the power over +13dbm, power consumption is about the same between the radios.

https://lowpowerlab.com/forum/rf-range-antennas-rfm69-library/rfm69w-and-rfm69hw-current-consumption/


[0_1496604219131_RFM69CW-V1.1.pdf](/assets/uploads/files/1496604221362-rfm69cw-v1.1.pdf) 

[tbowmo]

@lafleur

RFM69CW and RFM69HCW are not pin compatible.. One downside with hoperf, that they can't stick with a standard footprint layout..

[lafleur]

Well, that news to me. I've always use the HCW variant and did NOT noticed the pin change. My error for not looking at the detail... (This was not the case with the RFM69W and HW radios, both shared the same pin-out)

but again, using the HCW allow one to also use the RFM95 radios, and if you keep power below +13, power consumption is about the same... also the new RFM69 radio driver in 2.2b use adaptive power control as an option, this keep power use to a minimum saving power.

I just re-checked the data sheets, RFM95 and RFM69HCW do share the same pin-out.

[mfalkvidd]

@tbowmo from what I understand, they are pin compatible.

C and "non-C" are not pin compatible, but H and "non-H" are.

Older discussion on a similar topic: https://forum.mysensors.org/post/60304

[tbowmo]

@mfalkvidd

Check the datasheets, RFM69HCW has 16 pins, while RFM69CW only has 14 pins.

At least when I looked at the datasheets a couple of hours ago

[tbowmo]

@lafleur

Seems that you are right about the power consumption.. According to the datasheets, they use the same in receive mode, and when transmitting 13dBm.. So in theory it shouldn't do any harm on battery life..

Well I'll see if I can incorporate it in the second prototype..

[mfalkvidd]

@tbowmo said in Sensebender Micro mk2:

@mfalkvidd

Check the datasheets, RFM69HCW has 16 pins, while RFM69CW only has 14 pins.

At least when I looked at the datasheets a couple of hours ago

Yes you are right. Sorry for the confusion.

[bjornhallberg]

Could we do what Moteino has done and drop support for HW/W radios and opt for HCW/CW/RFM95/96/RFM12 using double sets of pads?
https://lowpowerlab.com/shop/product/99
Would be great if the community could settle on just one radio or a common way of doing things.

[tbowmo]

@bjornhallberg it is on the todo list.. First pcb are using the RFM69(H)W footprint.. As I already have samples of that pcb.. (still need to assemble though)

[evs]

Hi Thomas,

I like this design! Can you please tell the status and your future plans for this design?

Thanks,
EVS

[tbowmo]

@evs

Currently I have the first prototype pcbs without components, so need to make an order at mouser/digikey. This has been on my task list for the last couple of months though, as wife / kids have a lot of other projects for me during the summer time

[evs]

@tbowmo
Thanks for the update. But without the time frame. what needs to be done to finish. Is there software for the SAMD processor?

[tbowmo]

MySensors is already ported to samd21 so I expect things to be minor in order to get it up and running on samd20.

I will probably change footprint for the rfm69 module to use one that is compatible with rfm95 as well. And some other minor changes as well

[tbowmo]

A small update on this project, which I admit is taking longer than it should be (A lot of other projects has higher priority according to the wife)

I finally got the first prototype assembled saturday evening, I can upload firmware (via jtag/swd), and I have a semi hacked arduino core, that can build. But when programming the samd20e with this core, and a simple sketch toggling an output pin, nothing happens.

It seems that arduino halts in its initialization routine, waiting for some hardware to become ready after a reset, however I have not identified which part of the hardware yet.

[alexsh1]

@tbowmo

Hi, any update on this please?

[tbowmo]

Sorry, I got caught up in a couple of other projects, so still haven't got the first prototype up and run nok

[alexsh1]

@tbowmo said in Sensebender Micro mk2:

so still haven't got the first prototype up and run nok

Any luck with that at all? I really like they way the node is very small and with SAMD21

[tbowmo]

@alexsh1 bugger, I knew there where something that I had to do. The wife says that I have to finish the chicken coop automation first (opening / closing gates etc.).

[alexsh1]

@tbowmo ha ha ha - at least you are still married