Minimal design thoughts

[tbowmo]

@sharath-krishna

We are getting closer to a launch. A production partner has been found. All on-board hardware have been verified as OK! And I'm verifying the last bits (Want to have a complete node running, before giving a GO..) Also finishing the software that should be preloaded on the atmega.

Depending on how things are going, we should be able to make the first trial batch within the next couple of weeks (I hope!) which we then need to verify before starting the big machine.

Going to be an exiting spring this year :)

[doblanch]

To where will you be able to ship the nodes ? I live in France. I don't know where you are located...

[hek]

@doblanch

It will be shipped directly from the producer to any location.

[doblanch]

@hek Thank you for your reply. I'm going to deploy may be like 5/6 nodes. Another question, By any chance, did you think about a case which accept module+battery ?

[hek]

A case already was on my short-list and we could very well provide it.

Depending on demand it could be 3d-printed or for larger quantities done with mold injection by our partner.

But I would really need some help from a (talented) 3d modeller for this. Do we have anyone here that can help out?

The box must have a battery compartment for 2XAA. A big question is if it also should have space for an extra sensor?
Would be great if we could provide a couple of cover-options for things like motion (HC-SR501) and another for light/uv/ir sensor. Hope we can get creative together here.

[tbowmo]

A small update from the workbench here :)

The first rev.2 node is transmitting like it has never done anything else right now.

Next up is programming the bootloader, I am having some troubles in that area.. It seems that it is programmed, but I can't get it to accept any downloads from the arduino IDE.

Anyone got any hints for me to follow?

[Anticimex]

@tbowmo have you checked that the fuse configuration matches the HW with respect to frequencies and such?

[tbowmo]

@Anticimex

I have checked, and double checked fuses :) I'm using avrdude to program the bootloader directly, and it seems that it is starting up (the LED is lighting up as it is supposed to). Also when I program a sketch via ISP (using jtagice3) serial is working fine, so it seems that fuse settings is right for oscillator (at least)

But I might have missed something with the fuse settings.

I get these fuses
AVRDUDE -U lfuse:w:0xE2:m -U hfuse:w:0xDA:m -U efuse:w:0xFE:m -U lock:w:0xFF:m

from http://eleccelerator.com/fusecalc/fusecalc.php?chip=atmega328p&LOW=E2&HIGH=DA&EXTENDED=FE&LOCKBIT=FF

[Anticimex]

@tbowmo I am just taking wild guesses and the one thing that came to my mind if you seem to have bootloader running but cannot download is that the serial line is out of sync for some reason. But I have not dissected the arduino bootloader or the protocol so I am in deep murky waters making assumptions now :)

[tbowmo]

@Anticimex

Yeah, but it's hard to debug things in the bootloader.

[Anticimex]

@tbowmo Tell me about it. It's what I do for a living :)
You don't have means to pick up the serial line after the FTDI adapter by any chance? It perhaps reveals garbage or signs of non-matching BAUD rates.

[tekka]

@tbowmo

The fuse settings say 8Mhz internal, 2kb bootloader. Which bootloader are you using and did you adjust the baud settings in the boards.txt for the IDE (i.e. upload.speed=57600)? Also, do you get serial output at the set baud rate when uploading a simple serial output sketch via isp? Alternatively, I recommend recompiling the bootloader at 8Mhz for correct baud settings.

[tbowmo]

@tekka

It's DualOptiboot that I'm using, compiled for 8Mhz (internal RC oscillator).

[doblanch]

@hek Hello, I have a friend who is working with 3D modeling. i can study it. I do not guaranty for the moment, as it doesn't rely on me directly. however I can do the best, and try to move forward.
If I understand correctly, we need the place for the sensor+antenna+AA battery...
On the PCB, is there some hole to place some screws ?
How should we close the case ? by putting some screw or just putting a cover ? make sense ?

[hek]

@doblanch

The board has humidity/temperature build in. So we only need space for maybe one extra sensor (question is how large volume this would need?).
Punch out holes for wires to external things like permanent power, buttons or reed-switches.

Click on cover would be nice but requires more accuracy in the making. A screw wouldn't be a big problem.

Many variables... ;)

[tbowmo]

@tekka @Anticimex

Bootloader is working now.. I tried to compile for another target, atmega328_pro8, which worked.. (used "pro8" the other day, which also compiles for atmega328.. Hmm.. go figure)

[doblanch]

@hek I know , yes for the T/H sensor. As we put 2 AA battery, we have to know if we want to stack sensor/battery or not...otherwise, battery and sensor will be on the same plan.
I think that we can start without extra sensor, and add it in function of request, I'm going to buy a 3D printer, It will be my first tests.

[tbowmo]

Today the production files have been sent off to China, for the first batch of 5 prototypes build by them. We then need to verify them, and if they are found OK, we start a larger production run.

Feeling like Christmas is comming up :)

[markusand]

I'm too late for my suggestion, but maybe it can be implemented in future versions if considered. Just in order to simplify connectivity with sensors, spare pins could be accessible via grove connectors. However the board looks amazingly small!

[Ivan Z]

Why do not use CR123A accumulator?
It is smaller and can be charged.
And not nide regulator

I use box with charger. With CR123A accumulator.
http://www.ebay.com/itm/2600Mah-USB-Portable-External-Battery-Charger-Power-Bank-for-Cell-Mobile-Phone-/301514424642?pt=LH_DefaultDomain_0&var=&hash=item4633a90142

Very cheap