Category Archives: PCB Design

Tweaking the 128×32 LEDDMD Verilog

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There was a few problems with the code for the 128×32 LEDDMD. Every so often there was flickering at random spots on the screen. This was because of the way the display memory was updated. I already fixed it by putting a dummy state at the end of the display memory update. Doing so actually increased the speed that data could be sent to the FPGA. There is no waiting between the Latch pulls.

The last problem is that there is some slight ghosting on the screen. Due to the way the screen updates it looks like the Column data is updating slightly before the rows are updated. Because of this you get a ghost effect on the opposite side of the screen that is up one row.

I think the reason why is because there is a slight delay in the rows caused by the decoders. The current plan of attack is to buffer the Column data a couple cycles before outputting.

Pinball Homebrew Platform: Tommy

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I have had lots of requests for people wanting the hardware and PCBs for Reset Vector. I will be designing a pinball homebrew platform named Tommy. Key goals will be keeping cost down and complexity of the circuit down so it will be easy to build on .1″ perf board. Will be all through hole parts. Support for the 128×32 Display built in. Goal is to get the PCBs down to $15 a piece.

New Product coming. The ROFL Shield.

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You may know of the LoL Shield. It is a 14×9 charlieplexed LED display shield for the Arduino. I have been wanting to start making and offering Arduino Shields and decided I would make a LED Matrix shield.

The ROFL Shield is a 16×32 fully matrixed LED display that uses shift registers to expand the I/O of the Arduino. It uses 1.9mm LED modules for a fine pitch display. This will enable the Arduino to easily control 512 LEDs. The matrixing is performed by the Arduino via interrupts.

All shields I will be making will also be 100% compatible with the Gadget Gangster Propeller Platform. The shields will be configurable so users will not be locked into a specific pinout.

Price for the unassembled kit will be $30. PCBs will be offered for $3-$4. The kit uses SMD parts so there will be a SMD soldered option for $10 more. If you can solder you will be able to solder the SMD parts. There will be online video instructions on soldering and using every shield I design.

Propeller Development Stick V1.1 Finished

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I added a power LED and changed the layout so that all the parts are on one side of the PCB. It is still a double sided PCB but having all the SMD parts on one side reduces the cost a bit. I changed the headers a bit so that they are the standard .1″ spacing so “shields” could be made for it.

The final size is 47mm x 27mm and would cost roughly $1 per board.

Late night PCB work.

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I have had this idea to make a very small development board for the Propeller for a while now. The idea is that you can have it on your keychain or something and just plug the entire unit into a USB port. The port powers the device and there are female headers that allow you to plug other things into it. I might add a ADC just to get some analog signal input.

So I give you /drumroll the Propeller Development Stick or PDS V1.0.

32×128 DMD Rat Lining Halfway Done

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Halfway done with the rat lining for the PCB. A rat line is basically a visible line while PCB drawing that indicates net lists. A net list is just a list of all the pins and connections that are connected together. After I rat line I can lay down the traces.

The FPGA sees the display as a 64×64. This is due to I/O limitations. The odd rows are on the left and the even rows are on the right. So row 1 and 2 really make up the physical row 1.