8051 and 8052

The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 ohm resistor while the buffer output is at +1.5 volts.

This simple circuit will be helpful to those electronic enthusiasts who are interested in receiving audio signals of TV in all frequency bands, and also for those who want to inject TV signals using separate VIF and SIF units for repairing television sets. Persons having knowledge of electronic tuner of TV set would be aware that an electronic tuner requires 33-volt supply for its tuning.

A 555 timer can be used to generate a squarewave to produce a negative voltage relative to the negative battery terminal. When the timer output at pin 3 goes positive, the series 22 uF capacitor charges through the diode (D1) to about 8 volts. When the output switches to ground, the 22 uF cap discharges through the second diode (D2) and charges the 100 uF capacitor to a negative voltage. The negative voltage can rise over several cycles to about -7 volts but is limited by the 5.1 volt zener diode which serves as a regulator.

A simple calculator takes input from a keypad and displays the answer on a seven-segment LED. To build a simple calculator that adds and subtracts, four stages are needed. The first stage takes the serial input of a number from a keyboard, converts the number into hex, and stores it into memory. The second stage also takes serial input from the keypad only this time it is an operation key. The operation data informs the calculator what operation to be performed on the next number after the equal sign key is pressed.

This is the complete schematic for the development board. Address and Data bus wires are drawn separately (not in a bus), so that it's easy to color over them on a printout, if you choose to manually connect the wires. It really is easier to buy a bare circuit board, though.

8051 Based TV Display: In the course of a recent 8052.com thread , using '51 variants as audio/video co-processors came up. In response, i spent last Sunday implementing a micro only solution for a modest 256 x 190 pixel monochrome video generator for an equally modest 5" monochrome TV.

New version 8051SBC Microprocessor Learning Board, PCB and schematic available now. Cool circuit for experimenting the Nokia 3310 with 8051SBC, making the tiny scope! This new design includes brown-out protection and 20x4 or 16x2 LCD bus interface. Click here for Hardware and Software descriptions of the original version 8051SBC.

I decided to rename C52EVB to be 8051SBC. Since the cpu can be any 8051 compatible chips with 40-pin DIP package. The old day chips, say 8031, 8751, 8032 or the new chips, 89C51, 89C52, 89C51RD2 can be used without any problem. Some may think that your old chips were useless, now you can use it for many projects. The monitor program of new 8051SBC was placed at external 32kB EPROM. With this space, you can customize your own monitor code or even add the application program and have the DIP switch to boot it when power up.

I decided to rename C52EVB to be 8051SBC. Since the cpu can be any 8051 compatible chips with 40-pin DIP package. The old day chips, say 8031, 8751, 8032 or the new chips, 89C51, 89C52, 89C51RD2 can be used without any problem. Some may think that your old chips were useless, now you can use it for many projects. The monitor program of new 8051SBC was placed at external 32kB EPROM. With this space, you can customize your own monitor code or even add the application program and have the DIP switch to boot it when power up.

The 8052.com SBC is a single-board computer designed to be both useful and instructive in illustrating certain concepts commonly encountered in 8052-based development.