I wish you Merry Christmas and a Happy New Year. Let the coming year be prosperous joyful for all of us.

If your celebrating with family or friends or both may your turkey be tasty . Happy Thanksgiving!

“Because the dominant portion of the SparkFun mark, namely, SPARK, is phonetically identical and nearly visually identical to SI’s SPARC mark, and because it is used in connection with identical goods, we believe confusion is likely to occur among the relevant purchasing group.”

SparkFun will sure get allot of support from the community and I hope they’ll get pass this without too much trouble.

A counter is a very useful tool, i for one could use one when I’m winding coils. These days a counter project caught my attention, because it can be configured for many applications. Basically it’s a 4 digit decimal counter that can go from 0 to 9999 in either direction, can stop when it hits the maximum counting value or can be left in free run.

The maximum counting number can be set by the operator to a desired value, which is stored in the EEPROM of the PIC16F88. This is very helpful, looking at my coil winding example i can set this way the number of windings. You can also set it to count up or down and has an overflow output which can be used to control an external device once the counter reached the preset number, in my case to turn off the winding motor.

The clock input is port B0 of the PIC and can be set to count either rising or falling clock fronts with or without zero suppression. Schematics show a debounce circuit to be used with mechanical contact switches at the clock’s input, which will accept 5V logic only.

The counting is displayed on four 7-segment LEDs and operation mode is shown on other four LEDs. D7 will indicate overflow, D8 Count Hold and D9 and10 will indicate it’s counting up or down. The whole display is multiplexed, more information about that you can find here. There are five push buttons you can use to configure the counter.

Schematics, source code and hex file for PIC as well as detailed explanation of operation can be found in the link.

4 Digit PIC Counter: [Link] – [Via]

At first glance, the chip looks perfectly normal, but when you look on it’s back you can see four inductance windings:

These days most pharmacies use LED pharmacy crosses posted at their entrance to let people know there is a pharmacy there. The reasons are obvious, they look cool&hi-tech, they can be seen from distance and they can be customized really easy (well, easy customizing pretty much depends on how the manufacturer approaches things).

If you try to search the web about schematics or example codes for this kind of circuit you wont find any, and again i think the reason is obvious, the crosses are quite expensive and so is the profit for the manufacturer. So nobody is gonna post schematics for such a project, unless you’re a hobbyist and you’re having fun with electronics.

The project consists of one ATmega64, three ULN2003 and five 5×7 LED matrix from Kingbright(TA20-11EWA). I had the idea to build something like this but so far i haven’t had the time nor the knowledge to get it done. So i asked Morgoth if he would like to participate in the project. I sent him the LED’s, the drivers and the PCB and he started working. As you can see not many parts are involved , but the secret lies in the microcontroller, it’s the programming that does the job.

In the next pictures you can see the microcontroller board with the ULN2003 darlington arrays:

The circuit was designed to receive messages trough serial interface from a computer and than display them. Morgoth also designed a custom terminal for windows which provides easy access to the display.

In this test phase a serial interface by wire was used to transmit data between the terminal and the ATmega64, but a wireless or bluetooth module could be integrated with no problem.

Also as a note, the LED’s don’t light up really bright, for that to happen you need to use drivers on the positive rail. This also applies if you’re planning to take the project to another level and use bigger LED’s

And now, watch some videos with the LED Pharmacy Cross beeing controlled from the computer:

• LED Pharmacy Cross ATmega source code
• LED Pharmacy Cross terminal source code

In this project there are actually 3 chargers combined in a single PCB, each charger having an output voltage of 4.2V. You can cascade them to become charger fit for 2 or 3 cels Lipo pack. The transformer used is 3 x 8 VAC. As more and more devices are powered with LiPo batteries such a charger could come handy some day.

DIY LiPo Charger: [Link]