There many devices which can be controlled trough relays, like light bulbs, pumps, motorized doors, and the list can go on. Most of the relay boards available on the web are based on the serial interface, this has some drawbacks: limited distance, about 15meter based on the RS232 standard, and the new generation of motherboards lack this port. The presented board has ethernet interface using the ENC28J60 and the PIC18F4680, it also has a Real Time Circuit with battery backup, the ethernet interface beside its speed has a major advantage, the RJ45 contains a coupling transformer which is used to galvanically isolate the local electronics ground from the bus, this doesn’t mean that it will support a 230 common mode voltage, but offers protection to a certain limit.
The ethernet interface shows its full potential when comes along with a webserver, fortunately the author thought this to, he developed a simple web server which runs on the PIC, this way you can control the relays trough your network or even the internet.
This project was probably inspired from the commercially available gadgets, I think there are great but don’t think they worth 100-200$. Now their are many alternatives, from old laptop displays to OLED screens, the presented project uses a small display similar to the Nokia display and a PIC micro controller, the authors made the entire project public including the schematic and pcb files in Eagle format.
The screen used is cheap since it is a copy of the Nokia display, they aquired it from Sparkfun, where you can find source code for different types of micro controllers, the pictures are stored in a microSD card, in the current firmware version are some limitations to the bitmap format and no subfolders are supported. The PIC device used has free C compiler support from Microchip, which is also a great thing if you want to improve the firmware.
The pcb is really compact but not overcrowded, it is possible to replicate with hobbyst equipment, it is a great middle-level project for you to thinker.
Why pay hundreds for a commercial Data Acquisition System when you can build the PIC DAS for less than $50.00? The PIC DAS is built around a Microchip PIC16C63A microcontroller and contains an 8 bit bidirectional Digital I/O port, 12 bit, 8 channel A/D converter and a 12 bit, 4 channel output D/A converter. It is perfect for quickly controlling any project on your workbench! Use the Digital I/O to sense switch closures with the help from the built-in weak pullups, control OPAMP’s, power supplies and the like with the built-in D/A converters.
Measure temperature or sense voltage or current with the built-in A/D converter. The real usefulness of this system is that it has a known simple to use interface that uses real ASCII commands over an RS232 link. This method of control saves programming time that would otherwise be wasted controlling the test setup, instead of actually doing the test.
The author, Olivier de Broqueville designed this circuit for hi’s son who was dreaming of a small tool able to write symbols or pictures on a screen. The solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds, and a 16F628 , the dream could become reality.
Olivier also made a VB application that you can use to design patterns and export them apropriately.
The LED cube runs using a PIC16F690. Along with the brief explanation of how to make it, the author has also included the .asm file for the PIC and a piece of software written in VB.NET that you can use to create your own LED patterns. These can be exported as .asm files and put into the main .asm code.
