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Showing posts from October, 2009

Experiment No. 6: Read/Write Internal EEPROM Memory

An EEPROM (Electrically-Erasable Programmable ROM) data memory is one of the important features of flash-based PIC microcontrollers. It is called non-volatile to indicate that it retains the data even when the power is down. Practically speaking, if you want to design a digital lock system, then the password to unlock the system can be saved into the EEPROM, so that when the power is down, the password will still be saved. And other good thing is that the data can be easily modified or overwritten with software control. In this experiment, I am going to show you how to read and write in to the internal EEPROM memory of PIC16F628A using mikroC EEPROM library functions. Here is what we are going to do:

We will write 0s to 10 EEPROM locations. We will read them first, then write 0-9 to these locations, and turn the power off. We will turn the power on, and read the data in those locations and see. I have created a simple menu on LCD with Read, Write and Delete functions.

Experimental Set…

Experiment No. 5: Multiplexed Seven Segment Displays

In this experiment, we are going to learn how to interface more than one 7-segment LED display to a PIC Port using multiplexing technique. We are going to interface a 4-digit common cathode seven segment display to our PIC board. The multiplexing circuit is already built up in the board using 4 transistors and few resistors (Read Make Your Own PIC Development Board). The basic idea of multiplexing is that all seven segment displays are connected to the microcontroller in parallel and the microcontroller alternately prints ones, tens, hundreds, and thousands digits, selecting one at a time. The switching among the digits is so fast that it gives an impression of simultaneous light emission.

Experimental Setup:

1. Connect RA0 through RA3 to 7-Segment Digit Select headers DG1, DG2, DG3, and DG4 using jumper wires.
2. Insert 7FR5641AS 4-Digit Seven Segment module in to its place on the board.