Using the PIC18F2550 GLCD Text Test as a basis for further experimentation, I put together a simple and accurate graphical oscilloscope using a PIC18F2550 microcontroller and a AGM1264F graphical LCD. The oscilloscope measures the average voltage, the maximum voltage, the minimum voltage, the peak-to-peak voltage, and the zero-crossing frequency for a DC signal over 100 samples. The oscilloscope has a built in edge trigger function that can be set to capture on rise or fall (or disabled altogether). The time scale for the display is variable and can be easily redefined using the changeTimeDivision function. Likewise, the voltage range can be change to 0-5V, 0-2.5V, and 0-1.25V. The main limitations of this oscilloscope include relatively slow acquisition time and sampling rate (~60kHz) and the fact that the inputs are limited by the constraints of the internal ADC. However, it is a very nice display and I highly suggest you view the videos to see it in action. [Via]
The circuit is based on low-cost AtTiny2313 ATMEL microcontroller. It is able to read 125KHz RFID tags. Every tag is read then decoded, and its code is transmitted as ascii chars on the serial output. If the RFID code read is the same that is recorded in the micro non-volatile memory, then a relay pulses for 1,5 seconds, acting as electronic lock. The code stored in non-volatile memory is taken from the FIRST tag that is read from the circuit after burning the micro. The downloadable zip file contains the schematic diagram, the printed circuit board layout (single face, PDF 1:1 format) and the object file to burn in the micro. you can download document RFID 125KHz
AVR has two different programming modes called Parallel Programming Mode (Parallel Mode) and Serial Downloading Mode (ISP mode).
At the Parallel Mode, the device to be programmed is put on the programmer’s socket and +12 volts programming voltage is required to its RESET pin. Communicating between the programmer and the device is done in parallel programming commands, so that the programing speed is two times faster than ISP mode. This programming mode is used to pre-program many devices or/and ISP mode cannot use due to the board design. However, most programmers except STK500 seem not to support this programming mode. Using High voltage parallel programmer can recovery wrong fuse bit setting.
Schematics Download :
- Circuit Diagram for Parallel/HVS Programmer
- Socket Converters for Parallel Programmer
- Circuit Diagram for 8/14pin HVS Programmer
Software Download :