Anthony Barison / Mbed 2 deprecated GPIO_Hello_World

An example of how to initialize p20 as GPIO.

Dependencies:   mbed

main.cpp@0:4652951bde46, 2012-08-30 (annotated)

Committer:
a_baris
Date:
Thu Aug 30 12:02:40 2012 +0000
Revision:
0:4652951bde46
Child:
1:f0b14fe7874e
GPIO hello world.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
a_baris 0:4652951bde46 1 /*
a_baris 0:4652951bde46 2 This simple program is written has an example to show how pins of
a_baris 0:4652951bde46 3 mbed board can be programmed without the high-level abstraction of the
a_baris 0:4652951bde46 4 class DigitalOut.
a_baris 0:4652951bde46 5
a_baris 0:4652951bde46 6 References:
a_baris 0:4652951bde46 7 http://www.nxp.com/documents/user_manual/UM10360.pdf
a_baris 0:4652951bde46 8
a_baris 0:4652951bde46 9 Author: Anthony Barison
a_baris 0:4652951bde46 10 First release on: 30/08/2012
a_baris 0:4652951bde46 11 Last release on: 30/08/2012
a_baris 0:4652951bde46 12 */
a_baris 0:4652951bde46 13
a_baris 0:4652951bde46 14 #include <stdio.h>
a_baris 0:4652951bde46 15
a_baris 0:4652951bde46 16 /* pin 20 on the mbed board is memory mapped to port P1.31 of LPC1768
a_baris 0:4652951bde46 17 which I have defined as preprocessor directive. The value can be used as a mask to
a_baris 0:4652951bde46 18 read and write the status of "p20" */
a_baris 0:4652951bde46 19
a_baris 0:4652951bde46 20 #define PIN_20 0x80000000 /* this is the mask to be used in referring to p20 on the mbed board */
a_baris 0:4652951bde46 21
a_baris 0:4652951bde46 22 #define FIO1DIR (*((volatile unsigned int *) 0x2009C020)) /* output enable register */
a_baris 0:4652951bde46 23 #define FIO1CLR (*((volatile unsigned int *) 0x2009C03C)) /* clear output data register */
a_baris 0:4652951bde46 24 #define FIO1SET (*((volatile unsigned int *) 0x2009C038)) /* set output data register */
a_baris 0:4652951bde46 25
a_baris 0:4652951bde46 26 //volatile unsigned int *ClearOutputDataReg = (unsigned int *)0xfffff434;
a_baris 0:4652951bde46 27
a_baris 0:4652951bde46 28 int main()
a_baris 0:4652951bde46 29 {
a_baris 0:4652951bde46 30 int state = 0; /* state variable used as store of user input */
a_baris 0:4652951bde46 31
a_baris 0:4652951bde46 32 /* p20 initialization */
a_baris 0:4652951bde46 33 FIO1DIR = PIN_20; /* enable p20 as an output pin */
a_baris 0:4652951bde46 34 FIO1CLR = PIN_20; /* set 0 to p20 as a default value */
a_baris 0:4652951bde46 35
a_baris 0:4652951bde46 36 printf( "\r\nGPIO\r\nPossible inputs\r\n" );
a_baris 0:4652951bde46 37 printf( "0\tset p20 to 0\r\n" );
a_baris 0:4652951bde46 38 printf( "1\tset p20 to 0\r\n" );
a_baris 0:4652951bde46 39 printf( "-1\tterminate program\r\n\r\n" );
a_baris 0:4652951bde46 40
a_baris 0:4652951bde46 41
a_baris 0:4652951bde46 42 while(1) {
a_baris 0:4652951bde46 43
a_baris 0:4652951bde46 44
a_baris 0:4652951bde46 45 /* read user input from terminal */
a_baris 0:4652951bde46 46 printf( "State = ");
a_baris 0:4652951bde46 47 scanf( "%i", &state );
a_baris 0:4652951bde46 48 printf( "%i\r\n", state);
a_baris 0:4652951bde46 49
a_baris 0:4652951bde46 50
a_baris 0:4652951bde46 51 /* */
a_baris 0:4652951bde46 52 if( state == 0 )
a_baris 0:4652951bde46 53 FIO1CLR = PIN_20; /* p20 = 2 */
a_baris 0:4652951bde46 54 else if (state == 1)
a_baris 0:4652951bde46 55 FIO1SET = PIN_20; /* p20 = 1 */
a_baris 0:4652951bde46 56 else if (state == -1)
a_baris 0:4652951bde46 57 return 0; /* terminate program */
a_baris 0:4652951bde46 58 else
a_baris 0:4652951bde46 59 continue;
a_baris 0:4652951bde46 60 }
a_baris 0:4652951bde46 61 }