The STC89C52 is a microcontroller from the 51 and 52 series, similar to the AT89C52. There are only minor differences between them, and it can be directly used as a replacement. One of its key features is the built-in EEPROM, which allows for program downloading via the serial port. Additionally, its instruction execution speed is twice that of the standard 8051 architecture.
The STC89C52 is a low-voltage, high-performance CMOS 8-bit microprocessor that includes 8K bytes of Flash memory for program storage. It is manufactured using Atmel's advanced non-volatile memory technology and is fully compatible with the industry-standard MCS-51 instruction set and pinout 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 example, 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}; // Display patterns for 8 LEDs
uchar code wep[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}; // Row values for scanning
void delay(uint t) {
while (--t);
}
void main() {
uchar row, col, key;
while (1) {
P0 = 0xf0; // Set upper 4 bits high for scanning
row = P0; // Read P0 value
row &= 0xf0; // Mask lower 4 bits
if (row != 0xf0) { // Key pressed
delay(125 * 5); // Debounce delay
if (row != 0xf0) {
col = P0 & 0xf0; // Read column value
col |= 0x0f; // Set lower 4 bits to 1
P0 = col; // Write back to P0
row = P0; // Read again
row &= 0x0f; // Mask upper 4 bits
col &= 0xf0;
key = row + col;
}
}
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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