SAMD21 mini breakout board questions

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PaulRB
Posts: 8
Joined: Wed Feb 19, 2014 2:41 am
Location: West Yorkshire, UK

SAMD21 mini breakout board questions

Post by PaulRB » Wed Dec 27, 2017 10:23 am

Hi all,

I have some questions about the SAMD21 mini breakout board, please:
  1. I notice that the i2c and spi pins are not in breadboard-friendly positions for prototyping. But I also read that through some feature of the chip called SERCOM, it is possible to re-map these functions to other pins on the main 0.1" headers. Is this true, and where can I find out the details of how to achieve it?
  2. What is the typical current consumption in "normal" mode? What low power modes does the board/chip have, and are any of them supported by available Arduino libraries? Without removing any components, what's the minimum current I am likely to be able to achieve if (a) I just need the chip to wake after a fixed period (e.g. 15 mins) or (b) if I need it to respond to changes on certain pins (assuming that "responding" means something as simple as incrementing a count held in a variable in RAM, or perhaps reading an ADC and updating a total with the result).
  3. An obvious rival product would be PJRC's Teensy LC. Different chip manufacturer, but also based on ARM Cortex M0. The Teensy is priced considerably lower than the Sparkfun board. What would you say are the advantages of the Sparkfun board that would help me justify the extra?
The project(s) I have in mind for the board would be as LoRa sensor nodes. The board would need to connect an RFM95W radio module via SPI and to various i2c sensors (temp, humidity, that sort of thing). The nodes would ideally last months on AAA-size Li-ion 3.7V batteries, transmitting readings to The Things Network every 15 or 30 mins.

I am currently building my first prototype node using an atmega328, but the various Arduino libraries required to use the radio module, sensors, LoRa protocols etc. mean that 90% of the atmega's flash would be used on the simplest of nodes with a single sensor.

Sparkfun SAMD21 mini:
Image
Teensy LC:
Image

I look forward to any advice or pointers to useful documents!

Thanks,

Paul

PaulRB
Posts: 8
Joined: Wed Feb 19, 2014 2:41 am
Location: West Yorkshire, UK

Re: SAMD21 mini breakout board questions

Post by PaulRB » Sat Dec 30, 2017 4:24 pm

After more research, I realise the MCU on the Sparkfun board should not be compared to the Teensy LC. It's equivalent in the Teensy range, in terms of ram & flash (although not in terms of speed) is the Teensy 3.2. They are pretty much the exact same price. So I withdraw question 3.

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