Category Archives: Thoughts

Thermistors…Linear? How to make them so.

In my last video I showed off Lab 7 for EE445L which was the digital thermometer. To measure the temperature I used a thermistor which is a resistor that changes resistance based on the temperature.

These are non linear devices which make it a pain to get accurate readings directly.

More information on Thermistors:

8×8 LED Matrix Modules in 1.9mm size

So for the new 128×32 DMD I am using a smaller dot pitch LED Matrix with a size of 1.9mm. This means they are the same size as standard DMDs used on production machines. I secured a supplier and I can provide any color LED for the DMDs. Red, Orange, Amber, Blue, Green, ect. These are currently not compatible with production machines but are intended for Home Brew Pinball machines. They are very easy to work with.

Instead of the wacky voltages of a standard DMD mine only needs a +5V supply. Standard DMDs also are hard to drive with microcontrollers because you have to fill each “level” individually and you have to do it fast enough to keep up with the refresh rate. My DMD runs off a FPGA which means you don’t have to worry about how fast you send the data to the display. The FPGA takes care of all the matrixing and color levels. All you have to do is send the data in 1byte wide chunks which is perfect for Microcontroller use. If you are doing animations you can stream data off an SD card by doing byte writes and then pushing that data directly to the DMD.

Prices will be $250 for quantities 1-9 and $240 for anything over 10. They come with the SMD parts soldered on and the FPGA pre-programmed. You will need to solder the LED modules on. The LED modules will be tested to ensure that they are in full working order.