Because I want to participate in the electric competition, I came into contact with the STC89C52RC (A51) single-chip microcomputer
STC89C52RC pin function
1 power supply:
①VCC - chip power supply, connected to +5V;
②VSS - ground terminal;
2. Clock:
XTAL1, XTAL2 - crystal oscillator circuit inverting input and output.
3. Control line:
There are 4 control lines:
ALE/PROG: address latch permission/on-chip EPROM programming pulse
① ALE function: used to latch the lower 8-bit address sent by P0 port
② PROG function: on-chip EPROM Chip, during EPROM programming, this pin inputs programming pulses.
PSEN: External ROM read strobe signal .
RST/VPD: reset/standby power supply.
① RST (Reset) function: Reset signal input terminal.
② VPD function: In the case of Vcc power failure, connect to the backup power supply.
EA/Vpp: internal and external ROM selection/on-chip EPROM programming power supply.
① EA function: internal and external ROM selection terminal.
② Vpp function: For chips with EPROM on-chip, the programming power supply Vpp is applied during EPROM programming.
4. I/O port lines: P0, P1, P2, and P3 are four 8-bit ports.
Port P0 is a three-state bidirectional port, commonly known as a data bus port, because only this port can be directly used for read/write operations on external memory. Port 0 is also used to output the lower 8-bit map 1 address of the external memory. Since it is a time-sharing output, a latch should be added externally to latch the address data, the address is latched, and the signal uses ALE.
P1 port is an I/O port specially for users, and it is a quasi-two-way port.
The P2 port is used as the high 8-bit address line when the slave system is extended. When the external memory is not expanded, the P2 port can also be used as a user I/O port line, and the P2 port is also a quasi-bidirectional port.
Port P3 is a dual-function port, and each bit of this port can be independently defined as the first I/O function or the second I/O function. When used as the first function, the operation is the same as that of P1 port.
1. Marquee
Use the program to control the output level of P20-P27 (0,1) to realize the cycle lighting of the LED module D1-D8 light-emitting diodes, and complete the marquee effect.
/*定义LED引脚*/
#define LED P2
/*延迟函数*/
void Delay(unsigned int a)
{
while(a--);
}
//流水灯
void Running()
{
u8 i;
LED = 0xfe;
Delay(50000);//大约延时450ms
while(1)
{
for(i = 0;i<7;i++)
{
LED = _crol_(LED,1); //左移一位 0xfe(11111110)--->0xfd(11111101)
Delay(50000);
}
for(i = 0;i<7;i++)
{
LED = _cror_(LED,1); //右移一位 0x7f(01111111)--->0xbf(10111111)
Delay(50000);
}
}
}Define the LED as pin P2, P2 is assigned a value of 0xfe, binary is 11111110, a total of eight bits are respectively for P27-P20, when the P20 pin is 0-low voltage, the light is on, and 1-high voltage is off. Cycle left, right and wait for 450ms to turn on the next one
2. Independent button to control the buzzer
In the experimental version, there are 4 independent buttons k1-k4, respectively for the P30-33 pins of the STC80C51, when the button is pressed, the corresponding pin is grounded, that is, assigned a value of 0. Determine which of P30-P33 is 0 through the program, corresponding to the key press.
The BEEF of the buzzer is connected to the OUT5 pin of the wireless four-phase stepper motor ULN2003D, and the signal of this pin is affected by the P25 pin corresponding to IN5.
/*定义蜂鸣器*/
sbit BEEP = P2^5;
void C_buzzer()
{
while(1)
{
if(P31==0)//按下关闭
{
BEEP=1;
while(1)
{
if(P31==0)//当再次按下时，再次启动
{
break;
}
}
}
else
{
BEEP = ~BEEP;
Delay(50000);
}
}
}