Class 1 lights up the first LED light

8.1 light LED

Hardware connection diagram,

 

According to the hardware diagram, when the output of the 175-pin gpio [0] is 0, the LED is on. When the output of gpio [0] is 1, the LED is off, the base address of the gpio register is 0x8000d000, which is the offset address of the used registers.

 

First, select the gpio pin,

* (Unsigned short *) (0x8000d000 + 0x00) = 0x5555;

* (Unsigned short *) (0x8000d000 + 0x04) = 0x5555;

Then, gpio [0] is used as the output, and other pins are set as input.

* (Unsigned short *) (0x8000d000 + 0x08) = 0 xfffe;

Read the current gpio status to avoid changing the gpio status in subsequent operations, leading to other problems,

Unsigned short val;

Val = * (unsigned short *) (0x8000d000 + 0x10 ));

Finally, in the output register, set gpio [0] to 0. Specifically, the gpio [0] is set to 0 by the current state of gpio and the 0xfffe phase, other pins remain unchanged. And write the changed value to the gpio output register.

* (Unsigned short *) (0x8000d000 + 0x0c) = (Val & 0 xfffe );

To turn off the LED, Replace the last sentence:

* (Unsigned short *) (0x8000d000 + 0x0c) = (Val | 0x0001 );

The complete program for LED lighting is as follows:

 

Compile a MAKEFILE file for the program. You can use the MAKEFILE file of the hello program in Lesson 2 to modify it,

 

Next, download to the Development Board and run it,

 

 

8.2 key control LED light off

The hardware diagram shows that when the key is pressed, The gpio [1] pin status is 1. when the key is released, the gpio [1] pin status is 0, by reading the status of the gpio [1] pin, you can know whether the key is pressed, and continuously check the status of the key through a while loop. If the button is pressed, the current led status is changed once. The specific procedure is as follows:

# Include <stdio. h>

 

Void gpio_init (void );

Void led_on (unsigned short Val );

Void led_off (unsigned short Val );

 

Void main ()

{

Unsigned short val;

Unsigned short flag = 0;

Gpio_init ();

While (1)

{

Val = * (unsigned short *) (0x8000d000 + 0x10 ));

If (Val & 0x02) = 0x02)

{

If (flag = 0)

{

Led_on (VAL );

Flag = 1;

}

Else

{

Led_off (VAL );

Flag = 0;

}

}

}

 

}

 

Void gpio_init (void)

{

* (Unsigned short *) (0x8000d000 + 0x00) = 0x5555;

* (Unsigned short *) (0x8000d000 + 0x04) = 0x5555;

* (Unsigned short *) (0x8000d000 + 0x08) = 0 xfffe;

}

 

Void led_on (unsigned short Val)

{

* (Unsigned short *) (0x8000d000 + 0x0c) = (Val & 0 xfffe );

}

 

Void led_off (unsigned short Val)

{

* (Unsigned short *) (0x8000d000 + 0x0c) = (Val | 0x0001 );

}

8.3 conclusion

This course is mainly about programming. The problem is not difficult. It is generally the first program of embedded entry-light emitting diode, I have a general understanding of the status of the operation register to control the pin. At the same time, we also learned some differences between the Embedded C language and the Standard C language.

Class 1 lights up the first LED light