@badmannen Welcome back. The good news is that there's now a mysensors bootloader, which is even better because it allows over-the-air firmware updates for the atmega328p: https://www.mysensors.org/about/fota

@mfalkvidd Not just the NFC chips, but their billowy antennas also add to their size.

I wouldn't be surprised if a certain fully functioning nRF51 module has a smaller footprint:

@nca78 Good idea. Sice a laserprinter has even better dpi, maybe the barcode could be made even smaller.

@neverdie It appears that all the labelers that are able to print a "Data Matrix" barcode require the barcode to be created on a PC and then downloaded to the labeler.

I guess another criteria to consider is DPI. The higher the DPI, then, in principle, the smaller the Data Matrix barcode can be.

Then, because the goal is to keep the label small, it needs to be printed on a 1/4" wide tape, which seems to be the narrowest of all the tapes. Reportedly, some of the labels that can print 2D barcodes won't do it on a 1/4" wide tape. Go figure. Probably 300 dpi and/or 600 dpi should be possible, but not all labelers can print at that resolution.

Lastly to consider is the quality of the tape itself. From what I gather, the laminated tapes will last longer and hold up better than some of the cheaper tapes. As you might guess, not all of the labelers will print with that kind of tape.

Adding up all these constraints, it may be a $200+ labeler.... just to do something that I initially thought would be fairly easy. For comparison, a labeler than can do electrical cable and wiring labels costs just $29.

Maybe I should try attaching RFID/NFC chips instead? e.g.

https://www.ebay.com/itm/Lot-10PCS-Ntag213-NFC-Tags-Stickers-13-56-MHZ-ISO-14443A-RFID-Lable-Tags/143415648849?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D60710%26meid%3D58d2eb3272684262bef36841814ab2ef%26pid%3D100005%26rk%3D6%26rkt%3D12%26mehot%3Dco%26sd%3D323256457551%26itm%3D143415648849%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851

Alas, they are too large.

Lot 10PCS Ntag213 NFC Tags Stickers 13.56 MHZ ISO 14443A RFID Lable Tags

$1.28

27 available

Apparently the "data matrix" 2d barcodes are preferred because of their smaller size for labelling small electronic parts. The same format is used for "Direct Product Marking", where a laser etches the 2d barcode onto a part.

I'm looking for a labeller that can do this standalone and which can print small labels. It would be good for labeling small mysensors nodes that may not have much of a print area on them.

Or, in my case, I sometimes solder small SMT parts onto small, generic breakout PCB's to do a proof of concept circuit. Then, months or years later, I can't remember what the parts are on each of the boards. It would be great to have a little 2d label on it with that kind of information.

Anyone already doing this? Not sure which labeler to get.

@alowhum

"WRITE LINE
The minimum amount of data that can be written to the
panel is one line. The actual number of data bytes written depends on the horizontal resolution of the panel
itself. Therefore, a panel with a resolution of 400 × 240
will require a 400/8 = 50 bytes of data (plus overhead)"
https://www.sharpsma.com/documents/1468207/1485747/Memory+LCD+Theory%2C+Programming%2C+and+Interfaces

Remembering just 50 bytes for a 400 x 240 display doesn't sound particularly bad to me. I guess in the worst case, if you didn't want that burden in your MCU, you could dedicate a cheap, tiny slave MCU to mange it for you. For instance, maybe the main MCU just does println's, and the slave MCU handles the scrolling. I doubt it would be necessary, but one could fallback to that if push ever came to shove.

This appears to be new and it claims to have the benefit of e-ink type low-power but have a faster refresh: https://cdn-learn.adafruit.com/downloads/pdf/adafruit-sharp-memory-display-breakout.pdf

Indeed, looking at the sharp datasheet, it claims to be "super low power": https://cdn-learn.adafruit.com/downloads/pdf/adafruit-sharp-memory-display-breakout.pdf
Unfortunately, it doesn't state what the current or power actually is though. For that, it lists TBD. However, the printed unit of measurement is uW, so maybe it really will turn out to be low power.)

@zboblamont What is it that you recommend instead? Maybe (?) there are other issues, but my take is that, at the very least, his watchdog isn't working. So, why not start with that? At least then maybe he wouldn't be locked out of his system while he's on vacation.

But if you think he should put his effort elsewhere, then where exactly, and why?

@ykhokhlov There are a ton of not just POCs but also fully functioning mysensors nrf51/nrf52 nodes on openhardware.io Just click and have a look for yourself.