ARM7 lpc2148 GPIO key input test

Introduction: In this experiment, after pressing a key, the relevant signal is transmitted to 74HC165 in parallel, and then transmitted to the processor in serial mode. The processor controls the buzzer by controlling the P0.22 port (MAT0.0).

In this experiment, after pressing a key, the relevant signal is transmitted to 74HC165 in parallel, and then transmitted to the processor in serial mode. The processor controls the buzzer by controlling the P0.22 port (MAT0.0).

#include

//Macro definition

#define SCLK 0x01<<24

#define SCK0 0x01<<4

#define MISO 0x01<<5

#define MOSI 0x01<<6

#define RCK 0x01<<7

void HC595_Init(void);

void WriteByte(unsigned char data);

void Write595(void);

void HC165_CS(char flag);

unsigned char Read165(void);

void Delayn(unsigned long n);

//595 extended interface data display cache

unsigned int HC595_DATA = 0xFFFFFFFF;

//Initialize 595 interface

void HC595_Init(void)

{

IO0DIR |= MOSI|RCK|SCK0;

IO1DIR |= SCLK;

IO1CLR |= SCLK;

IO0DIR |= RCK;

HC595_DATA = 0xFFFFFFFF; Write595();

}

//Write bytes

void WriteByte(unsigned char data)

{

unsigned char i;

//IO0CLR = RCK;

for(i=0;i<8;i++)

{

if(data&0x01) IO0SET=MOSI;

else IO0CLR=MOSI;

IO1SET=SCLK;

data>>=1;

IO1CLR=SCLK;

}

//IO0SET = RCK;

}

//Refresh 595 data

void Write595(void)

{

IO0CLR = RCK;

WriteByte(HC595_DATA&0xff);

WriteByte((HC595_DATA&0xff00)>>8);

WriteByte((HC595_DATA&0xff0000)>>16);

WriteByte((HC595_DATA&0xff000000)>>24);

IO0SET = RCK;

}

//165 chip select

void HC165_CS(char flag)

{

if(flag) ////CLK INH writes high level,

HC595_DATA &= ~(1<<1);

else

HC595_DATA |= (1<<1);

Write595();

}

//Read the data of 165

unsigned char Read165(void)

{

unsigned char RD=0,i;

HC165_CS(1); //

IO1CLR_bit.P1_25 = 1; //Write 1 to make the corresponding pin output low level, even if S/L (pin 1) gets low level, before the arm board receives data, the pin must be pulled low, the purpose is to load the data on the parallel data A--H into the internal register, which reflects the LOAD function

Delayn(10);

IO1SET_bit.P1_25 = 1; //Write 1 to make the corresponding pin output high level. Then, in the process of receiving data, the pin must be pulled high to enable the data in the register to be moved, so as to move the data from QH or QN' into the microcontroller. This reflects the SHIFT function.

for(i=0;i<8;i++)

{

RD <<= 1; //Shift left one bit

if(IO0PIN&MISO) //MISO0 is the serial data output by 74HC165. Check whether 74HC165 receives the data. If MISO0 is not 0, it means that the data is received.

RD |= 1; //Accept high position first

IO0SET=SCK0; //The clock is high, and the next data is shifted out on the rising edge (CE is allowed to change from low to high only when CP is high)

Delayn(10);

IO0CLR=SCK0; //Clock low level (We only need to pull down or raise a port of the arm processor, so that the data can be received step by step. Please remember that the rising edge is valid.)

}

HC165_CS(0);

return RD;

}

main()

{

PINSEL0=0x000000;

PINSEL1=0x000000; //All pins are connected to GPIO

unsigned char HC165_DATA;

IO1DIR_bit.P1_25 = 1;

IO1SET_bit.P1_25 = 1;

PINSEL0_bit.P0_5 = 0;

//IO0DIR_bit.P0_5 = 0; //HC165 input pin

IO0DIR=1<<22; //Buzzer control port is set to output, the rest are input

HC595_Init();

while(1)

{

HC165_DATA = Read165();

if((HC165_DATA&(1<<4))==0) IO0SET=1<<22; //When KEY2 is pressed, the buzzer sounds (see below for explanation)

else IO0CLR=1<<22; //Release KEY2, the buzzer stops beeping

}

}

//Delay cycle number

void Delayn(unsigned long n)

{

while(n--);

}

Final Notes:

Explanation of if((HC165_DATA&(1<<4))==0) IO0SET=1<<22 in the main function, 1<<4 makes the 4th bit become 1, there is a functional diagram in the 74HC165 data sheet:

 It can be seen that the peripheral pin corresponding to the 4th bit is 3. From the connection diagram of the 74HC165 in the first figure above, it can be found that it is connected to KEY INT2, so the corresponding key is KEY2.

The data transmission method of 74HC165 in the program needs to be studied. The reason why 74HC595 is used is that the board of Litian Electronics connects the chip select (165 CS) of 74HC165 to 595 during design, so 595 must be operated accordingly.