8Bit or 32Bit processors

[NeverDie]

Took a closer look at the Sparkfun SAMD21 PCB. It's actually a four layer PCB, not the more ordinary two layer PCB. On the other hand, the Adafruit SAMD21 is a two layer PCB. The four layers explains why the Chinese knock-ffs look different from the Sparkfun version: https://www.aliexpress.com/item/SAMD21-M0-Mini-32-bit-ARM-Cortex-M0-core-Pins-soldered-Compatible-with-Arduino-Zero-Arduino/32779698644.html?spm=2114.01010208.3.10.0u636X&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10130_10068_5010013_10136_10137_10060_10138_10155_10062_437_10154_10056_10055_10054_10059_303_100031_10099_10103_10102_10096_10052_10053_10107_10050_10142_10051_5030014_10084_10083_10119_10080_10082_10081_10178_10110_519_10111_10112_10113_10114_10182_10185_10078_10079_10073_10123_10120_10189_142-10050,searchweb201603_9,ppcSwitch_4&btsid=36be8280-4e44-474b-b3e4-2c9eef009d58&algo_expid=09284286-c141-4a88-bce8-2d8bb9d233d6-1&algo_pvid=09284286-c141-4a88-bce8-2d8bb9d233d6

[NeverDie]

I think it will be important to see how big a minimalist SAMD21 board needs to be while still remaining 2-layer. I'm guessing about half the size of the Adafruit board, since a lot of that board real estate is just prototyping area plus pinouts from the SAMD21.

Anyhow, I'm looking forward to not worrying about how many libraries I can load before running out of memory! Even that alone--at least during development--is worth spending some extra money. :)

[NeverDie]

What kind of hardware have people here had success in using for burning a bootloader and changing fuses on a SAMD21? For instance, will I need Atmel's ICE, or do these work just as well:
https://www.aliexpress.com/item/1PCS-AVR-JTAG-USB-Emulator-Debugger-download-AVR-JTAG-ICE-Download-Programmer-Atmega/32789255835.html?spm=2114.01010208.3.26.iO9ONh&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10130_10068_5010014_10136_10137_10060_10138_10155_10062_437_10154_10056_10055_10054_10059_303_100031_10099_10103_10102_10096_10052_10053_10107_10050_10142_10051_5030014_10084_10083_10119_10080_10082_10081_10178_10110_519_10111_10112_10113_10114_10182_10185_10078_10079_10073_10123_10120_10189_142-10052_10152_10113_10120,searchweb201603_16,ppcSwitch_4&btsid=f5ac2ded-aae9-478c-a52d-08f2e72cc936&algo_expid=44d9bdb3-4da4-4810-a84b-23ba1337c57b-3&algo_pvid=44d9bdb3-4da4-4810-a84b-23ba1337c57b

or https://www.amazon.com/Microcontroller-circuit-Debugger-Programmer-Emulator/dp/B00C7W4IWA/ref=sr_1_2?ie=UTF8&qid=1496575267&sr=8-2&keywords=swd+jtag

[scalz]

@NeverDie you need SWD interface for burning a bootloader to them.
ST-link v2 should be ok and you can find cheaper clone, no idea for your other link.
Otherwise, like i said above, i'm using a Segger Jlink OB like this one http://www.ebay.com/itm/New-J-Link-OB-ARM-Debugger-Programmer-Downloader-replace-v8-SWD/141854905580?_trksid=p2047675.c100623.m-1&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41375%26meid%3D188c2e52c5484de68b250d6f7dfb4d72%26pid%3D100623%26rk%3D2%26rkt%3D6%26sd%3D400943523132
Again you can find them cheaper at aliexpress, on my side i keep the insulating plastic cover in place

[NeverDie]

A bit off topic, but I like what this guy did with putting an OLED onto his SAMD21 board. Not sure where to get them, but they must be cheap, because his whole board costs $15 on Tindie.

https://www.tindie.com/products/microwavemont/ultra-zero-a-successor-of-sduino-zero/?pt=full_prod_search

[gohan]

@NeverDie don't they have something similar on adafruit?

[mfalkvidd]

http://www.ebay.com/itm/0-96-I2C-IIC-SPI-Serial-128X64-White-OLED-LCD-LED-Display-Module-fr-Arduino-NEW-/232314247092

https://www.aliexpress.com/item/Hot-Selling-0-96-inch-128X64-Blue-OLED-Display-128-64-LCD-Screen-Board-30pin-SSD1306/32806209969.html

[NeverDie]

@gohan

This is the most "similar" one I've found on Adafruit:

https://www.adafruit.com/product/2900
That and the one that mfalkvidd just posted look a lot bigger to me.

[gohan]

well it is similar :D
maybe I confused another one that has a different processor, I remember they had one with a small LCD and processor together

[mfalkvidd]

The Adafruit one is 128x32. From the picture, it looks to be about twice the width of the one on the tindie board. So maybe it is 64x32? Like this one
https://www.aliexpress.com/item/White-0-49-inch-OLED-Display-Module-64x32-0-49-Screen-IIC-for-Arduino-AVR-STM32/32779893498.html

[NeverDie]

@mfalkvidd Looks like you nailed it. :)

[NeverDie]

So, back to the main topic: does SWD completely replace JTAG and everything else as a kind of all-in-one interface to the SAMD21? Is there even any point to using USB at all anymore? Can everything be done just through SWD?

[tbowmo]

@NeverDie

SWD is the "jtag" interface for ARM Cortex processors.. Consider it as the atmel programmers for the atmega processors.. Only thing is that the SWD interface is common between all cortex processors, regardless of the vendor (STM, Atmel, Intel etc)

For the average john doe, that is used to Arduino (the IDE), USB is making things a lot easier, as you do not need to connect an external programmer to your device..

[NeverDie]

I have an AVR Dragon, which also uses a 10-pin j-tag connection, but I see from this: http://www.atmel.com/webdoc/atmelice/atmelice.using_ocd_physical_swd.html
that it's not going to be pin compatible with the 10-pin j-tag connection used for SAMD21. Instead, it needs to be:

The cabling that comes with the el cheapo SWD programmers doesn't seem right. It should be 10 pin (really 2x5 pin) to match the recommended. The Sparkfun SAMD21 board appears as though it is made to dock with such a cable.

Even the Segger doesn't appear to come with quite the right cable for an SAMD21.

It should be using one of these cables instead: https://www.adafruit.com/product/1675

Right?

[scalz]

SWD is using only two signals for programming data and clock. then vcc for ref, and gnd. that's all.

[NeverDie]

@scalz
That would be just the top four pins in:

I guess one simply hand wires the connections every time one connects?

[scalz]

yep exactly

[alexsh1]

@lafleur I have tried a few of those boards you listed. Moteino Mega and RocketScream Ultra Pro V2 are the two I would always use for >32kb sketches. Moteino Mega is still my favourite - I have three of these. One is working as MySensors rfm69 GW. Another one is deployed for LMAC LoraWAN stack with TTN GW.
RocketScream has more powerful processor and a battery charger. I used it for GPS tracking. Excellent board.
Adafruit Feather - I looked briefly, but I did not like it does not have the on-board eeprom (why? It is not cheap) and comes with an amplified version of rfm69 only - not good for a battery powered sensor.

[alexsh1]

@tbowmo said in 8Bit or 32Bit processors:

I have created the sensebender micro mk2, which still needs verification.. (For my part, activity have been low due to other work related projects..)

I saw it on the github. When are you planning to release it proving all goes well?

[alexsh1]

@scalz said in 8Bit or 32Bit processors:

using d21e, so i burn a bootloader like i said above with a Segger OB j-link, clone i guess. Then you just need usb

Is this one any good ?
Ebay link