hello_radio_016 assembled by Shelby Doyle

Board fabrication by milling

This board requires a ground plane underneath the circuitry to define the impedance of the microstripline traces coming out of the MRF49XA.  The preferred route is to mill the board out of a double-sided PCB blank.  Alternatively, the top traces could be milled from a single-sided PCB blank with a strip of adhesive copper foil on the back to define the ground plane.  In either case, at least one connection should be made between the top and bottom ground planes, preferably at the left edge of the board.
For the top traces, use an 1/64" end mill with a diameter setting of 0.38 mm to ensure the toolpath is generated for all cutouts and isolations
$ png_path hello_radio_016-top.png hello-radio_016-top.path 1 0.38 4 0.5 0.5 # in out error diameter contours offset-overlap intensity

hello_radio_016-top.png @ 2400 dpi

For the via drils and board cutout, use a 1/32" end mill with a diameter setting of 0.79 mm
$ png_path hello_radio_016-top.png hello-radio_016-top.path 1 0.79 4 0.5 0.5 # in out error diameter contours offset-overlap intensity

hello_radio_016-cutout.png @ 2400 dpi

Board artwork for milling

hello_radio_016-top.png (Top layer image)
hello_radio_016-cutout.png (Cutout image)

Schematics, board layout, assembly diagram, BOM

hello_radio_016-sch.pdf (Schematic)
hello_radio_016-brd.pdf (Board layout)
hello_radio_016-assembly.pdf (Assembly diagram)
hello_radio_016-bom.txt (Bill of Materials)

Object code, source code, boot loader, makefile


Eagle design files


Antenna options

Instead of an SMA connector and antenna, a length of wire can be soldered directly to the center pad of the SMA connector footprint.  The wavelength of an 868 MHz carrier is about 34.5 cm, so use at least 1/4 of this wavelength (8.6 cm).

Serial interface and protocol

[to be added]

Fuse settings

avrdude -U lfuse:w:0xf6:m -U hfuse:w:0xdd:m -U efuse:w:0x01:m -U flash:w:hello_radio_20MHz.hex -p m168 -P /dev/ttyACM0 -c stk500v2

Brian Mayton, David Cranor, Rehmi Post