A device which contains the microprocessor with integrated peripherals like memory, serial ports, parallel ports, timer/counter, interrupt controller, data acquisition interfaces like ADC, DAC is called micro controller.
List the features of 8051 micro controllers ?
Single supply +5v operation using HMOS technology.
4096 bytes program memory on-chip.
128 data memory on chip.
4 register banks
2 multiple modes, 16 bit timer/counter
Extensive Boolean processing capabilities.
64KB external RAM size.
32 bi-directional I/O lines.
Explain the operating mode 0 of 8051 serial port ?
In this mode serial data enters and exists through RXD, TXD outputs the shift clock. 8-bits are transmitted or received:8-data bits(LSB first). The baud rate is fixed at 1/12 the oscillator frequency.
Explain the operating mode 2 of 8051 serial port ?
In this mode 11 bits are transmitted (through TXD) or received (through (RXD): a start bit(0), 8 data bits( LSB first), a programmable 9th data bit and a stop bit(1). On transmit, the 9th data bit can be assigned thevalue 0 or 1. On receive, the9th data bit go into the RB8 in special function register SCON, while the stop bit is ignored. The baud rate is programmable to either 1/32 or 1/64 the oscillator frequency.
Explain the mode 3 of 8051 serial port ?
In this mode, 11 bits are transmitted (through TXD) or (received (through RXD): a start bit(0), 8 data bits(LSB first), a programmable 9th data bit and a stop bit(1).It is same as mode 2 except the baud rate. The baud rate in mode 3 is variable.
Explain the interrupts of 8051 micro controller ?
External interrupt 0 (IE0)
Timer interrupt 0 (TF0)
External interrupt 1 (IE1)
Timer interrupt 1 (TF1)
Serial port Interrupt
Receive interrupt (RI) - lowest priority
Transmit interrupt (TI)
How many bytes of internal RAM and ROM supported by 8051 micro controller ?
128 bytes of internal RAM and 4 bytes of ROM.
Define machine cycle of 8051 ?
8051 machine cycle consists of 6 states, S1 through S7. One state is made up of 2 clock pulses. Thus 12 clock period constitute one machine cycle. Two clock periods in a state is termed as phase 1 and phase 2.
What are the special function of port 0 of 8051 ?
Port 0 is used as a multiplexed low order address/data bus during the external memory access. When ALE is enabled, the address on port 0 pins are latched and bus is ready to act asa data bus when ALE is low.
What are the alternative function of port 3 of 8051 ?
Serial data input (P3.0), serial data output (P3.1), external interrupt 0 (P3.2), external interrupt 1 (P3.3), external input for timer 0(P3.4), external input for timer 1 (P3.5), external memory write pulse (P3.6), external memory read (P3.7) are the alternative functions of port 3.