University of Plymouth - Stages 1, 2 and 3
Lab version
Fork of
Task328
by 
Nicholas Outram
main.cpp@3:25b67e69f6fc, 2019-09-12 (annotated)
- Committer:
- noutram
- Date:
- Thu Sep 12 15:12:04 2019 +0000
- Revision:
- 3:25b67e69f6fc
- Parent:
- 2:52faa20a51b4
2019
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| noutram | 0:c6ec99d3da16 | 1 | #include "mbed.h" |
| noutram | 0:c6ec99d3da16 | 2 | #define N 100000 |
| noutram | 2:52faa20a51b4 | 3 | #define RELEASED 0 |
| noutram | 2:52faa20a51b4 | 4 | #define PRESSED 1 |
| noutram | 3:25b67e69f6fc | 5 | |
| noutram | 3:25b67e69f6fc | 6 | #ifdef TARGET_NUCLEO_F429ZI |
| noutram | 3:25b67e69f6fc | 7 | //#define ONBOARD |
| noutram | 3:25b67e69f6fc | 8 | #endif |
| noutram | 3:25b67e69f6fc | 9 | |
| noutram | 3:25b67e69f6fc | 10 | #ifdef ONBOARD |
| noutram | 3:25b67e69f6fc | 11 | DigitalOut red_led(LED3); //CountUp is in its critical section |
| noutram | 3:25b67e69f6fc | 12 | DigitalOut yellow_led(LED2); //CountDown is in its critical section |
| noutram | 3:25b67e69f6fc | 13 | DigitalOut green_led(LED1); //counter != 0 |
| noutram | 3:25b67e69f6fc | 14 | #else |
| noutram | 0:c6ec99d3da16 | 15 | DigitalOut red_led(D7); //CountUp is in its critical section |
| noutram | 0:c6ec99d3da16 | 16 | DigitalOut yellow_led(D6); //CountDown is in its critical section |
| noutram | 0:c6ec99d3da16 | 17 | DigitalOut green_led(D5); //counter != 0 |
| noutram | 3:25b67e69f6fc | 18 | #endif |
| noutram | 0:c6ec99d3da16 | 19 | DigitalIn button(USER_BUTTON); |
| noutram | 0:c6ec99d3da16 | 20 | |
| noutram | 0:c6ec99d3da16 | 21 | //Shared mutable state |
| noutram | 0:c6ec99d3da16 | 22 | volatile long long counter = 0; //Volatile means it must be stored in memory |
| noutram | 0:c6ec99d3da16 | 23 | |
| noutram | 0:c6ec99d3da16 | 24 | //Increment the shared variable |
| noutram | 0:c6ec99d3da16 | 25 | void countUp() |
| noutram | 0:c6ec99d3da16 | 26 | { |
| noutram | 0:c6ec99d3da16 | 27 | //RED MEANS THE COUNT UP FUNCTION IS IN ITS CRITICAL SECTION |
| noutram | 0:c6ec99d3da16 | 28 | red_led = 1; |
| noutram | 0:c6ec99d3da16 | 29 | for (int n=0; n<N; n++) { |
| noutram | 0:c6ec99d3da16 | 30 | counter++; |
| noutram | 0:c6ec99d3da16 | 31 | counter++; |
| noutram | 0:c6ec99d3da16 | 32 | counter++; |
| noutram | 0:c6ec99d3da16 | 33 | counter++; |
| noutram | 0:c6ec99d3da16 | 34 | counter++; |
| noutram | 0:c6ec99d3da16 | 35 | counter++; |
| noutram | 0:c6ec99d3da16 | 36 | counter++; |
| noutram | 0:c6ec99d3da16 | 37 | counter++; |
| noutram | 0:c6ec99d3da16 | 38 | counter++; |
| noutram | 0:c6ec99d3da16 | 39 | counter++; |
| noutram | 0:c6ec99d3da16 | 40 | } |
| noutram | 0:c6ec99d3da16 | 41 | red_led = 0; |
| noutram | 0:c6ec99d3da16 | 42 | |
| noutram | 0:c6ec99d3da16 | 43 | //Last to finish turnes out the green light |
| noutram | 0:c6ec99d3da16 | 44 | if (counter == 0) { |
| noutram | 0:c6ec99d3da16 | 45 | green_led = 0; |
| noutram | 0:c6ec99d3da16 | 46 | } |
| noutram | 0:c6ec99d3da16 | 47 | } |
| noutram | 0:c6ec99d3da16 | 48 | |
| noutram | 0:c6ec99d3da16 | 49 | //Decrement the shared variable |
| noutram | 0:c6ec99d3da16 | 50 | void countDown() |
| noutram | 0:c6ec99d3da16 | 51 | { |
| noutram | 0:c6ec99d3da16 | 52 | //YELLOW MEANS THE COUNT DOWN FUNCTION IS IN ITS CRITICAL SECTION |
| noutram | 0:c6ec99d3da16 | 53 | yellow_led = 1; |
| noutram | 0:c6ec99d3da16 | 54 | for (int n=0; n<N; n++) { |
| noutram | 0:c6ec99d3da16 | 55 | counter--; |
| noutram | 0:c6ec99d3da16 | 56 | counter--; |
| noutram | 0:c6ec99d3da16 | 57 | counter--; |
| noutram | 0:c6ec99d3da16 | 58 | counter--; |
| noutram | 0:c6ec99d3da16 | 59 | counter--; |
| noutram | 0:c6ec99d3da16 | 60 | counter--; |
| noutram | 0:c6ec99d3da16 | 61 | counter--; |
| noutram | 0:c6ec99d3da16 | 62 | counter--; |
| noutram | 0:c6ec99d3da16 | 63 | counter--; |
| noutram | 0:c6ec99d3da16 | 64 | counter--; |
| noutram | 0:c6ec99d3da16 | 65 | } |
| noutram | 0:c6ec99d3da16 | 66 | yellow_led = 0; |
| noutram | 0:c6ec99d3da16 | 67 | |
| noutram | 0:c6ec99d3da16 | 68 | //Last to finish turns out the green light |
| noutram | 0:c6ec99d3da16 | 69 | if (counter == 0) { |
| noutram | 0:c6ec99d3da16 | 70 | green_led = 0; |
| noutram | 0:c6ec99d3da16 | 71 | } |
| noutram | 0:c6ec99d3da16 | 72 | } |
| noutram | 0:c6ec99d3da16 | 73 | int main() { |
| noutram | 0:c6ec99d3da16 | 74 | |
| noutram | 0:c6ec99d3da16 | 75 | green_led = 1; |
| noutram | 3:25b67e69f6fc | 76 | wait(2); |
| noutram | 0:c6ec99d3da16 | 77 | Timeout t1; |
| noutram | 0:c6ec99d3da16 | 78 | |
| noutram | 0:c6ec99d3da16 | 79 | // TRY EACH OF THESE LINES IN TURN. |
| noutram | 0:c6ec99d3da16 | 80 | // ALL IT DOES IS CHANGE THE TIMING OF THE ISR, NOT THE FUNCTION |
| noutram | 0:c6ec99d3da16 | 81 | |
| noutram | 0:c6ec99d3da16 | 82 | if (button == PRESSED) { |
| noutram | 0:c6ec99d3da16 | 83 | //VERSION 2: short delay allowing main to be preempted - you might want to tweak this value |
| noutram | 0:c6ec99d3da16 | 84 | t1.attach_us(&countDown, 15); |
| noutram | 0:c6ec99d3da16 | 85 | } else { |
| noutram | 0:c6ec99d3da16 | 86 | //VERSION 1: 2s - ENOUGH TIME FOR COUNTUP TO FINISH |
| noutram | 0:c6ec99d3da16 | 87 | t1.attach(&countDown, 2); |
| noutram | 0:c6ec99d3da16 | 88 | } |
| noutram | 0:c6ec99d3da16 | 89 | |
| noutram | 0:c6ec99d3da16 | 90 | //Run count up on the main thread |
| noutram | 0:c6ec99d3da16 | 91 | countUp(); |
| noutram | 0:c6ec99d3da16 | 92 | |
| noutram | 0:c6ec99d3da16 | 93 | //Now spin-lock for ever |
| noutram | 0:c6ec99d3da16 | 94 | while(1) { |
| noutram | 0:c6ec99d3da16 | 95 | asm("nop"); |
| noutram | 0:c6ec99d3da16 | 96 | }; |
| noutram | 0:c6ec99d3da16 | 97 | } |
| noutram | 0:c6ec99d3da16 | 98 |