RFX 1284p dev/dep board w/ prototyping area and nRF24L01+ headers (Kit)
Meet “Skinny Bob”!
Positioned midway between the Uno-class RFX 328p dev/dep board and the Due-class RFX Teensy 3.x Carrier board, the RFX 1284p/nRF24L01+/proto dev board (aka “Skinny Bob”) is a Mega-class board based on the ATmega 1284p microcontroller, with 16kB SRAM, 128kB flash program memory, and 4kB EEPROM.
As with all other RFX kits, it uses only through-hole components (no SMT), so only basic soldering skill and equipment is required for fast and easy assembly.
Some key features:
- It has been developed as a lean (but not bare bones) dev board based on the recently refreshed Arduino “Mighty 1284p” core. It uses a pin mapping making it maximally compatible with the standard Uno R3 shield header layout.
- The additional pins (A6, A7, and digital pins D24-D31) are broken out onto a separate 10 pin header. Once the “Mighty 1284p” core files are added to the Arduino IDE (latest files can be downloaded here), it is programmed selecting the “Bobuino” 1284p variant from the boards menu (whence the “Skinny Bob” name.)
- At ~5x10cm, it is the same physical size as a Mega. The bigger board allows for some additional features not seen on the smaller form factor RFX boards, however – e.g., provision for *two* 800mA TO-220 voltage regulators, one supplying the 5V rail, the other a 3v3 rail (which gives much more 3v3 power capacity than on either an Uno or Mega). Configurable power options via a jumper setting allows you to select running the 1284p microcontroller off either the 5V rail or the 3v3 rail, or even directly from Vin if appropriate. Or leave the jumper disconnected if you have some other arrangement in mind.
- There is also a header specifically for connecting a USB-to-TTL converter cable (6-pin cable header using the FTDI “GRN” to “BLK” pattern adopted by many cables.) (Note that a neat CP2102-based USB-To-TTL mini board that can plugged into the header is also available as an optional kit add-on.)
- Socketed chip means you can replace the chip and not have to toss the whole board in case of a “magic smoke” event.
- And of course, like all RFX boards, it features an on-board prototyping area and built-in support for nRF24L01+ modules using either a hardware SPI or software SPI interface. It also supports a second grid-aligned set of headers that allow for easy expansion on to standard 0.1” pitch proto board and breadboards.
So it’s a lean design, still with lots of flexibility, but with enough creature comforts to move it one step up from the “bare bones” category — it’s a Skinny Bob! Squeezing in to occupy that middle ground, providing significantly more resources than a 328p, yet retaining the pleasing simplicity and robustness of a 5V AVR 8-bitter in a DIP package. :-)
Bill of materials (BOM) for kit below:
BOM for 1284p dev board ("Skinny Bob")
1 Atmel ATmega1284p-PU (40 pin DIL package)
1 DIL-40 (wide) socket
1 16MHz xtal
2 22pF ceramic caps
4 0.1 uF ceramic caps
2 10uF electrolytic caps C5, C7
1 10uH inductor L1
1 LD1117v33 voltage regulator (TO-220)
1 LD1117v50 voltage regulator (TO-220)
1 3mm LED (blue)
1 1/4W resistor 10K (reset pull-up) R1
1 1/4W resistor 1K (series LED) R2
1 diode (schottky) 1N5817 (or equiv) D1
1 diode 1N4007 (or equiv) (reset) D2
1 DC power jack 2.1mm barrel-type PCB mount
1 6x1 (for FTDI cable header, could substitute female 6x1 if preferred)
2 3x2 (ICSP header, and power configuraton jumper block)
2 pin jumpers
2 4x2 (nRF24 headers)
2 40x1 strips, cut as follows:
"Long" male pin gender changing headers
Schematic can be viewed here.
Full kit assembly instructions can be downloaded here.