I have just finished designing a small SAMD20G18 and RFM95 based general purpose node suitable for solar power. The board is presently being fabricated at Seeed Studios. You can order a board here: SOLoRa at seeedStudioFusion
naturally, I have not tested it yet and I have more documentation to complete, but you can follow the project or go to see the PDF schematics, EagleCAD files for this initial version 1.0 here: SOLoRa - Github
More information will trickle in as it develops.
-Joe
Santa Rosa community TTN (#santarosa)
and 180Studios
The board is a result of wanting to have a common and flexible platform to base many example LoRa examples and future workshops for our local Makerspace (180studios.org) and is being driven by volunteers of both 180 Studios and our local TTN community.
Again, at this time I have not gotten the boards back from fab so the final features may vary from the original design goals.
Board Goals:
Low-cost components
Easy (ish) Assembly.
a. Uses QFP package processor and 0603 Rs and Cs
– Can be soldered by hand by most people using standard soldering iron. One exception is the accelerometer, which can be soldered using a reflow heat gun and a little training
Arduino compatible
a. Uses the same device as the Arduino Zero (use existing Arduino Zero bootloader? - TBD)
FeatherWing compatible
a. Can use with Adafruit’s featherwing expansion boards or use the header for a protoboard mezzanine
Multiple power options to targeting wider IoT applications, particular field applications
a. Solar
– Has a CR123 battery clip for a LiFePo4 battery used as a power reservoir. (400mAh)
– On-board regulator charges LiFePo4 to constant voltage. Solar cell size constrains max charge current.
b. Rechargeable Li-Po or external battery pack
– For standard indoor applications
– On-board USB micro connector and charger IC
c. Lithium (primary cell) i. Battery clip will also house a standard CR123 3V Lithium, which has ~1000mAH capacity
d. USB 5V for desktop development (or use with a USB battery bank?)
e. On- board adjustable regulator
– Change Resistor values to adjust VDD:
– to drop Li-Po, external battery pack output voltage and USB 5V to a safe level.
– determines LiFePo4 charge voltage.
Small size: 2.3 x 2 inches
a. Has mounting holes to match an inexpensive watertight enclosure
b. All components mount on one-size only. The bottom is component free to increase mounting versatility.
c. 2-layer board, cheaper to fabricate.
ARM Cortex M0 (SAMD20G18A)
a. Low power, high speed capable, 256K Flash
Optional on-board sensors, indicators
a. 3-Axis Accelerometer
b. Temperature
c. Programmable Red LED
Development Options
a. Arduino IDE (use as an Arduino Zero? TBD)
b. Atmel Studio
– Atmel Studio has Arduino templates to program like Arduino,
– Use standard C programming form
– Full debugging capability (breakpoints, watch variables)
– $20 JTAG debugger hardware required for this feature
Sorry, yes, TNN is my motivation for this board. Although, this is just hardware with a LoRaWAN compatible transceiver. It’s really in the software, and application that make it TTN or any other network. I plan to use the LMIC library on Arduino IDE for starters because many of the people in our group are new to microcontrollers.
TTN is the network I am promoting. I believe in its mission and future. I wanted to create a general purpose, low cost, flexable, maker space build-able LoRaWAN node board that our TTN local group can use in conjunction with our local maker space to motivate others.
The “RFM69” reference in the schematic applies to the library symbol I am using. Anything in the RFM9xx family will work (but not necessarily for TTN). I plan to use an RFM95W (915MHz) module.
it is now visibile, thx!
