ArmfulKST / Mbed 2 deprecated microbit_blink_low_level

IoT 2018

Dependencies:   mbed

Fork of microbit_blinky by BBC

main.cpp@1:0b38b848a5f0, 2018-09-20 (annotated)

Committer:
f3d
Date:
Thu Sep 20 09:17:38 2018 +0000
Revision:
1:0b38b848a5f0
Parent:
0:025387782f3e
Child:
2:83f7d8e01b11
Low level button and blink example for BBC Microbit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
JonnyA 0:025387782f3e 1 #include "mbed.h"
f3d 1:0b38b848a5f0 2
f3d 1:0b38b848a5f0 3 // Button A is on P0 bit 17
f3d 1:0b38b848a5f0 4 // Pin labelled "0" on edge connector is in fact connected to P0_3
f3d 1:0b38b848a5f0 5 volatile uint32_t * P0OUT = (uint32_t *)0x50000504;
f3d 1:0b38b848a5f0 6 volatile uint32_t * P0DIR = (uint32_t *)0x50000514;
f3d 1:0b38b848a5f0 7 volatile uint32_t * P0IN = (uint32_t *)0x50000510;
f3d 1:0b38b848a5f0 8 volatile uint32_t * P0CONF = (uint32_t *)(0x50000700);
JonnyA 0:025387782f3e 9
f3d 1:0b38b848a5f0 10 void dly(volatile uint32_t len)
f3d 1:0b38b848a5f0 11 {
f3d 1:0b38b848a5f0 12 // "volatile" modifier is necessary here
f3d 1:0b38b848a5f0 13 // to prevent the compiler from optimizing
f3d 1:0b38b848a5f0 14 // this software delay to nothing
f3d 1:0b38b848a5f0 15 while(len--);
f3d 1:0b38b848a5f0 16 }
f3d 1:0b38b848a5f0 17 int ButtonAPressed()
f3d 1:0b38b848a5f0 18 {
f3d 1:0b38b848a5f0 19 // Button A pulls down so bit is zero when pressed.
f3d 1:0b38b848a5f0 20 if ((*P0IN & (1 << 17))==0)
f3d 1:0b38b848a5f0 21 return 1;
f3d 1:0b38b848a5f0 22 else
f3d 1:0b38b848a5f0 23 return 0;
f3d 1:0b38b848a5f0 24 }
JonnyA 0:025387782f3e 25 int main() {
f3d 1:0b38b848a5f0 26
f3d 1:0b38b848a5f0 27 *P0DIR = (1 << 3);
f3d 1:0b38b848a5f0 28 P0CONF[17] = 0; // On power up, input buffer is not connected so must do this
f3d 1:0b38b848a5f0 29 while(1) {
f3d 1:0b38b848a5f0 30 if (ButtonAPressed())
f3d 1:0b38b848a5f0 31 *P0OUT = (1 << 3);
f3d 1:0b38b848a5f0 32 else
f3d 1:0b38b848a5f0 33 *P0OUT = 0;
JonnyA 0:025387782f3e 34 }
JonnyA 0:025387782f3e 35 }