PCB & schematic (Kicad format)

Schematic PDF

Pin diagram


Arduino integration



The board is based on the ATMEGA1284P and has (when fully populated)...

Ethernet. A Wiz820 module (uses the W5200 chip)
micro-SD card (module from PJRC)
2 x logic level serial port (or 1x logic level, serial0, and 1 x RS485, serial1)
battery backed RTC (DS1307 or 1338)
Radio connector for the commonly available nRF24L01 2.4Ghz radio
power LED, user LED
reset button

All of these features have been tested in the Arduino environment using readily available libraries (the reset button was easy).

Some flexible powering options are possible (see the schematic). There are two power rails on the board which can be split (5V & 3.3V) or combined for 3.3V only (or even 5V only). This allows for low power running at just 3.3V. If high micro clock speeds are required (I have run it at 22.1184Mhz), then the rails can be split to run the micro (& RTC + RS485) at 5V. The 3.3V is for the Ethernet, SD card and radio. Depending on what you fit, you can juggle the powering to suit. Just be sure not to feed 5V to any of the 3.3V-only stuff or the magic smoke will escape and your board will be dead.

The Wiznet module has the RST (reset) and PD (power-down) pins connected so low power Ethernet is available by wake-up-and-do-something type programming, and the ethernet interface can be fully reset without resetting the board.

Programming can be by the standard AVR 6-pin programming header, or if an Arduino bootloader is installed, by using a FTDI-basic serial programmer (but a wiring harness is required as the pins don’t line up). Serial programming was an afterthought as I use the 6-pin header.

The links on the left point to the Kicad PCB & Schematic files plus whatever else I think may be relevant.

The zipped board file also contains another zipfile which is the artwork I sent to Seedstudio. If you just want some PCB's as-is then its easy, just email the artwork file to the PCB service and in about 3 weeks your 10 shiny PCB's will arrive. Happy soldering :).

When I get my act together a bit more, I'll add links to other relevant support information and files to add to the Arduino environment to make it all work.

I dont think I would have ever got this far if the Goldilocks board was not evolving at the same time. I was able to use its board profile and eventually I managed to slightly tweak the bootloader (from Phillip Stevens work) which saved me a great deal of pain. Another invaluable source of information is maniacbug's site. As well as lots of helpful info on the 1284, his nRF library made testing the radio system easy.

I'm very much a learner in C. My adventures into the Arduino world are to help me along this path. I've always been a bit of a die-hard assembly language programmer but the vast amount of resources available with Arduino and the oh such nice toys! It was just too much of a temptation so here I am.

Pin layout of board

The interfaceable (if there is such a word) pins are laid out as below. All of them are on a 0.1” matrix, including the two regulator pinouts (but not the 4 corner PCB mounting points) so this lends itself to easy expansion by plugging onto stripboard.

There are 3 PWM pins available (D5/6/7) so enough to run RGB LEDs, or something else....

The dimensions shown below are the furthest distances between the pins, not the PCB size, which is slightly larger.