Pulled RESET VECTOR’s 96×16 DMD out of the parts bin and managed to find the old code to get it working again. Going to turn it into a Twitter Feed/Clock/Weather wall thing.
Design ended up having only 10 LVDS signals broken out as that required less unique parts. The connectors are expensive (1-282834-0) running ~$5.70 in singles. I will be looking into alternatives to see if I can get the cost down. I found some on AliExpress but I will need to order them and test them to see if they are any good.
I also included a 4 position auxiliary power connector to power up external circuits. No power safety though (fuses/TVS) so use at your own risk!
Started work on a expansion board for the DE0 FPGA development board. Planning on having 4 8-bit bi-directional level shifters giving 32 I/O and breaking out 12 LVDS signals to screw terminals. Basically a simple digital acquisition add on. Using the expansion template I made for the DE0 a couple days ago.
LVDS will be buffered to protect the FPGA. Have not picked the buffer chip yet. The bi-directional level shifter is the SN74LVC8T245PWR by Ti. Handles 1.65V to 5.5V on both sides and has basic ESD protection. I am debating putting over voltage protection on the I/O of the level shifters. A 50ohm resistor in series with the I/O plus a 5.6V TVS Diode should do the trick and not add to much cost to the board.
Uploaded the template that I use for making hardware expansions for the DE0 FPGA Dev board. It fits on the 2 40Pin GPIO Headers on the right side of the board. Files are for Eagle V6.0+
Parts, PCBs, and Stencils arrived earlier this week so I put together the three prototypes for REV4. Above is pre reflow.
Directly after reflow.
Magnified picture of the board. Turned out great. FTDI chip flashes and Propeller programs over USB. The new MAX11613 ADC works as well. I will be posting the driver code for that shortly.
Some changes from REV 3 to REV 4.
Render of the PCB from OSHPark.
Top stencil pattern. The through hole pads on the micro USB connector are going to be soldered with the “Paste In Hole” method. I have not tried this yet but if it works I will be able to cut out an entire operation during production of the boards.
Finished the next revision of the Propeller Development Stick REDUX. The power switching has been changed to fix the flakiness of the past revision. I switched the TPS2115 to a TPS2113. This seems to have fixed the weird power switching issues. The layout has change completely. SD card slot is on the top side of the board and the power circuity and ADC are on the bottom now.
Finished drawing the case last night for 3D printing. Used SketchUp to draw it as its free. Still searching for that perfect 3D modeling program. SketchUp is an ok piece of software. Compared to AutoDesk 123D V9 it lacks some features but the newer 123D Design (they changed the name slightly) its pretty lame.
X-RAY view for giggles.