This page contains the (relatively unchanging) information about v1.0 of the SARduino644 board.
This revision was created to address the errata from v0.1, as follows:
- The reference designators were corrected and gaps removed.
- We labeled as many passives as we could.
- We separated the breakout area from the microcontroller pins, for more flexibility in how to use the breakout area.
- We added additional breakout for the FTDI cable input, as well as a simple auto-reset circuit and selection jumper.
- We slipped in extra power and ground rails wherever there was space.
- We added breakout space for raw VIN, safe VIN, and VCC in.
- We repositioned the bypass caps, and added pads for optional 805 bypass caps as an alternative.
We are very happy with how the improved prototyping area turned out, and the auto-reset circuit has proved its worth already.
Because we had this round made as a 2-board panel on a 10cm x 10cm board from Seeed, we’ve included the panelized gerbers, along with the single-board gerbers we used to construct the panel. If you order a board, don’t be surprised to see the edge where the panel was separated, though it should be a clean cut.
|SARduino644 v1.0||everything (.zip)||.sch .png||.brd .png||single.zip panel.zip|
Bill of Materials
Here is a Mouser BOM of all the parts listed below, for easy ordering.
|S1||40-pin IC Socket||0.600″ wide, 0.1″ pitch|
|IC1||ATmega644P||Microcontroller (or ATmega1284P)|
|R1||10K ohm||Pullup resistor for RESET switch|
|Y1||16MHz Crystal||Oscillator (or 16MHz Ceramic Resonator, omit C1,C2)|
|C1,C2||18-30pF Cap||Capacitors for Crystal (match required value)|
|C3,C4||0.1uF Cap||Bypass capacitors for MCU, consider putting right at 5V/GND and A+/GND pins instead of labeled positions|
|FTDI||1×6 header||6-pin FTDI cable programming connection (optional)|
|SV1||Reset button||6mm x 6mm tactile momentary switch|
|PWR-SEL||1×3 header||3-pin power selector (external or USB)|
|ICSP||2×3 shrouded header||Standard AVR ICSP header|
|SW1||Reset button||6mm x 6mm tactile momentary switch|
|C7||0.1uF ceramic capactior||For auto-reset circuit|
|JMP1 / JMP2||0.1″ jumper||To enable / disable auto-reset, and for power selection.|
|EXTERNAL POWER SUPPLY OPTION:|
|D1||1N400X||Input protection diode (e.g., 1N4001 or 1N4004)|
|PWR-JACK||2.1mm jack||External Power Jack|
|VR||7805||5V Regulator (any IN-GND-OUT should work, or 3V3 if you want that)|
|C5,C6||10uF-100uF||Power Supply Filter Caps|
- The silkscreen, especially on the reverse side of the boards, is a bit smudged. Some of it is hard to read because it is so tiny, in other cases, I think it’s the smudging. That’s just how they came from Seeed, I’ll make an inquiry, but I don’t expect much to come from it. In the future, maybe cut down the line width, and increase the text size, where possible.
- Some of the labels for the bypass caps are hidden beneath the socket. I did this on purpose, but now I’m having second thoughts.
- The FTDI connector, the external power jack, and the voltage regulator need to be labeled on the silkscreen.
- An (optional) power LED circuit would be nice.
- The power supply filter caps and the voltage regulator, when placed, make accessing the SC-70 breakout very difficult. If you intend to use that breakout, please consider populating it before the power supply circuit.
- None of the vias are tented, we’ll have to see if there’s some way to do that. Maybe the vias were too large.