Boards and parts arrived today from OSH Park and Mouser. Soldered them up after work.
Close up of the board. Not a ton of parts…all connectors. The handle idea worked out pretty well. The board can be pulled out of the dual 40pin headers with ease!
Expansion mounted in the DE0 DEV board. Gotta write up some verilog to test it out now.
Ordered the PCBs from OSH Park. Should be getting them in about two weeks.
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.
I had a couple spare PSOCs to test the part tray with and train the pick and place. The PSOCs fit very well with little wiggle. Will be training the machine on the placement of the parts on Friday.
Here is a short little video of the pick and place positioning the FCC connectors onto the PCB panel. I am using double sided stick tape to replicate the holding force of solder paste. The pick and place is running at 10% speed to prevent the connector from sliding off the nozzle.
This is the screen printer we are currently using at MacroFab. It is an old semi-automatic printer but it works well for its age. It has a vacuum table to hold down the pcb and suck the screen to the pcb. Put some coated stainless blades on it for smooth paste squeegee action.
The Pic-32 on the Pinheck Pinball System is a TQ-100 package which is .4mm pitch. We used a solder stencil and placed the part via the pick and place. Stencil was .1mm in thickness. Ran 25 boards and had no solder bridges.
At MacroFab, I have been working with a DP2006-2 Madell pick and place for the past 6 months doing low scale pcb manufacturing while we test our software on it. Some parts (like big MCUs and connectors) come on what is called a tray where the parts are laid out in a X-Y matrix. The pick and place machine knows the amount of parts and the offsets so it can pick up the parts in the tray.
For one of the jobs we are doing I needed two trays, one for the PSOC4 and another for the FFC connector for the LCD. The DP2006-2 is pretty limited in pick and place area so I decided to make a part tray that would hold both parts. First I measured out the metal tray area on the DP2006-2 and looked at the datasheets of the parts for the physical dimensions. Then used SketchUp to draw out the tray. I gave each part .15mm clearance around the maximium size of the part. This takes care of any tolerance issues. If the tolerance is to big then the part can become crooked in the tray and the machine might have difficulties in picking up the part.
The Sketchup file can be downloaded here and the STL output for a 3D printer can be found here. I sent the files over to my friend Chris Kraft who printed the model with his MakerGear M2.
Chris sent me the model along with some test squares so I can test the ESD spray paint adherent to the PLA material the part tray was made out of. It adhered just fine to the bare PLA material so I went ahead and sprayed the part tray.
So far I have tested it with the FFC Connector and it has worked great! The PSOC4 fit but I have not trained the machine on it yet. I will post a picture when I load them into the machine.