Microcontroller AT89S51/52

Use AT 89S51 IC has several benefits and advantages, including high-level constraints, external components hardwere less, ease of programming. And cost-efficient. AT 89S51 IC has an internal program that is easy to remove and re-programmed over and over - again. In this plane AT 89S51 IC serves as the central control of all aircraft activity. Starting from the timer to control the length of the electrode work. In this plane AT 89S51 IC is also used as modifiers for the thermal sensor temperature is converted in units of mineral content that is displayed in the form of seven segment displays.

IC image AT89S51

Some functions of the pins on the IC legs AT89S51 microcontroller which is:

Port 0
Port 0 is the 8-bit open drain bi-directional port I / O. at the time as an output port, each pin can be passed to the input TTL-8. When the logic one is written to port 0, then these pins can be used as input high berimpendansi. Port 0 can be confirmed to demultiplex the data path / addres bus for reading the external program and data memory. In this mode P0 has internal Pullup. Port 0 also enerima code for programming Flash bytre. And issued a code of byte during program verification

Port 1
Port 1 is an 8 bit bi-directional port I / O with internal Pullup. 1 has the output port that can be connected with 4 TTL inputs. When logic '1 'is written to port 1, pin it on the pull Hight using internal pullup, and can be used as input. Port 1 also receives the addres dab Flash programming for verification.

Port 2
Port 2 is 8-bit bi directional port I / O with Pullup. Port 2 output buffers can spend four TTL inputs. When the logic one is written to port 2, then they dipull Hight with internal Pullup and can be used as input.

Port 3
Port 2 is 8-bit bi directional port I / O with Pullup. The output buffer of port 3 can be skipped four TTL inputs. When the logic one is written keport 3, then they will dipull Hight with internal pullup, and can be used as input. Port 3 also has a variety of functions / facilities. Port 3 also receives some control signals for Flash programming dab verification.

RST
Reset input. Hight logic on this pin will reset the machine cycle (IC).

ALE / Prog.
Addres output pulse is used to latch Enable lantching byte addres lower than during access to external memory. This pin is also the program pulse input during Flash programming. If desired, ALE operation can be disabled by setting bits to 0 of SFR at location 8EH. With Bit Set, ALE disabling, will not affect if the microcontroller in the external execution mode.

PSEN
Program Store Enable is the signal used to read external program memory. When the 8951 executes code from external program memory, PSEN is activated twice each machine cycle.

EA / VPP
External Access Enable, EZ must be positioned to GND to enable the device to feed the code of the program memory locations starting at 0000H up to FFFFh. EA should be positioned to VCC for internal program execution. This pin also receives 12-volt programming voltage (Vpp) during Flash programming.

XTAL1
Input for inverting oscillator amplifier and input to inte rnal clock to pengoperaian circuit.

XTAL2
Output from the inverting oscillator amplifier.