In the November 2010 issue of Nuts and Volts, we built a wireless device to alert us when the garage door was left open. Since then, I’ve had several readers suggest other uses for the ”Wireless Garage Door Transmitter”. The transmitter unit has the capability of inputting three signals on the terminals provided. The unit works such that any type of switch that connects to ground and to a terminal that is closed will cause a green light to display. When opened it will display a red light and if the alarm button is armed it will cause the alarm to sound. Here are three hacks to allow you to use the transmitter for other purposes.
How would you like to generate your own bitmaps to display on the 128x64 graphics kit that was introduced in the April 2010 issue of Nuts & Volts? Or even go the next step and produce animation with the same basic techniques? We’ll show you how easy it is to add this capability to your 16-bit Micro Experimenter using a cool tool from http://www.pavius.net
In part 1 of this feature, we discussed how to use the MCP23S08 device to add digital I/O to the Experimenter. Now, we’ll discuss the associated software to make this work. The demo software is written in PIC24F C Compiler and is available here as a software downloadable project. The demo uses the MCP23S08 device to emulate an eight bit output port. All of the outputs are configured to drive their own individual LEDs through an external current limiting 100 ohm resistor. The microcontroller turns each LED on and off, one at a time, in sequence. In addition, the LCD on the Experimenter announces the demo.
Let’s jump right in with an overview of the software.
If you’ve been following the 16-Bit Micro Experimenter series in Nuts & Volts, you are already familiar with its solderless breadboard environment and the fully programmable 10 line I/O expansion bus that comes with the kit. The 10 lines can be assigned to be digital, analog or even connected to any of the PIC24F Microcontroller’s internal extensive peripheral set (i.e. dual UART, five CCP modules, ADC, Real time Clock Calendar, dual SPI, and dual I2C).
But, if you find this 10 line I/O capability constraining, there’s a really cool enhancement to add even more I/O to your kit…
This project details how to build a Smart/SIM card reader/writer for experimentation and investigation of SIM & Smart cards.Once the reader design is built, the open source software can be used to read from and write to the card. Together they can be used to backup/restore stored SIM card data, recover deleted SMS’s and phone contacts, examine the last phone numbers dialed, etc.
If you are a beginning musician, it is often desirable to have a metronome to help keep cadence while playing. This circuit describes a variable rate metronome constructed with easy to find components.
Sometimes it is necessary to locate a pesky short circuit on a printed circuit board or other wiring assembly. The short could be caused by a solder bridge or a fried component. For example, if a circuit has the supply voltage shorted to ground, the audible milliohmmeter can be used to find the location of the short. It produces a tone that is proportional to the resistance between the test probes (100 milliohms or less). When the resistance decreases, the output frequency also decreases. If you can perceive small changes in frequency, resistance changes on the order of a few milliohms can be determined. Figure 1 is the schematic of the audible milliohmmeter.