Archives For 8051

Relay interface on I/O ports

February 23, 2011 — 1 Comment

When a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact.  The movement either makes or breaks a connection with a fixed contact.   When the current to the coil is switched off, the armature is returned by a force approximately half as strong as the magnetic force to its relaxed position.  Usually this is a spring, but the gravity is also used commonly in industrial motor starters. Continue Reading…

LED interface on I/O ports

February 7, 2011 — 1 Comment

Connect LED to I/O port with 220k resistor and 5V power supply. Connect cathode of LED to pin port and anode with resistor. You can still connect LED without resistor also but performance will not be good on those case becasue we are not limiting current to diode(LED). Continue Reading…

You can interface switch on input/output port of 8051 micro controller. Ports are TTL (Transistor Transistor Logic) pins. Its has 0V or 5V on pin depending upon ON or OFF.  Give 5V supply to input port and connect switch to ground with respect to that port. Continue Reading…

To use microcontroller in your project you need basic circuit to make use of all functions of 8051 microcontroller.

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Standard serial interfacing of microcontroller (TTL)  with  PC or any RS232C Standard device , requires TTL to RS232 Level converter . A MAX232 is used for this purpose. It provides 2-channel RS232C port and requires external 10uF capacitors.

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