The STC89C52 is a member of the 51 and 52 series microcontrollers, similar to the AT89C52. There are only minor differences between them, making it possible to directly replace the AT89C52 with the STC89C52. One key advantage of the STC89C52 is its internal EEPROM, which allows for program downloading via the serial port. Additionally, the instruction execution speed is double that of standard 8051-based MCUs.
The STC89C52 is a low-voltage, high-performance CMOS 8-bit microcontroller with 8KB of Flash memory, which is programmable and erasable. It is manufactured using ATMEL's advanced non-volatile memory technology and is fully compatible with the industry-standard MCS-51 instruction set and output pin configuration. This makes it ideal for a wide range of embedded applications where reliability and performance are essential.
Below is an example of a matrix keyboard program implemented on the STC89C52 microcontroller. In this setup, the keyboard is connected to the P0 port, and the output is displayed on the P2 port.
#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit key1 = P3^2;
sbit key2 = P3^3;
uchar code tab[] = {0x3f, 0x06, 0x5b, 0x4f, 0x66, 0x6d, 0x7d, 0x07, 0x7f, 0x6f, 0x77, 0x7c, 0x39, 0x5e, 0x79, 0x71, 0x00}; // Define the LED display values
uchar code wep[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
void delay(uint t)
{
while(--t);
}
void main()
{
uchar row, col, key;
while(1)
{
P0 = 0xf0; // Set P0 to 11110000 to scan the rows
row = P0; // Read the current value of P0
row = row & 0xf0; // Mask the lower nibble
if(row != 0xf0) // If no key is pressed, continue
{
delay(125 * 5); // Debounce delay
if(row != 0xf0)
{
col = P0 & 0xf0; // Read column data
col = col | 0x0f; // Set the lower nibble to 1s
P0 = col; // Write back to P0
row = P0; // Scan again
row = row & 0x0f; // Mask the upper nibble
col = col & 0xf0; // Mask the lower nibble
key = row + col; // Combine row and column values
}
}
switch(key)
{
case 0xee: P2 = tab[0]; break;
case 0xde: P2 = tab[1]; break;
case 0xbe: P2 = tab[2]; break;
case 0x7e: P2 = tab[3]; break;
case 0xed: P2 = tab[4]; break;
case 0xdd: P2 = tab[5]; break;
case 0xbd: P2 = tab[6]; break;
case 0x7d: P2 = tab[7]; break;
case 0xeb: P2 = tab[8]; break;
case 0xdb: P2 = tab[9]; break;
case 0xbb: P2 = tab[10]; break;
case 0x7b: P2 = tab[11]; break;
case 0xe7: P2 = tab[12]; break;
case 0xd7: P2 = tab[13]; break;
case 0xb7: P2 = tab[14]; break;
case 0x77: P2 = tab[15]; break;
}
}
}
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