RTOS example - inter-task communication by using a message queue. One task provides numbers and sends them to a second task which displays them on a 4-digit 7-segment LED tube driven by two 74HC595 shift registers. Hardware: NUCLEO_F446RE board with Arduino Multifunction Shield. The ShiftOut Library by Ollie Milton …
Dependencies: mbed mbed-rtos ShiftOut
main.cpp
- Committer:
- cspista
- Date:
- 2022-02-24
- Revision:
- 0:fb9706dc4816
File content as of revision 0:fb9706dc4816:
#include "mbed.h" #include "rtos.h" #include "ShiftOut.h" // Ollie Milton, https://os.mbed.com/users/ollie8/code/ShiftOut/ DigitalOut buzzer(D3); Serial pc(USBTX,USBRX); //UART via ST-Link typedef uint32_t message_t; Queue <message_t, 4> queue; void display_thread(void const *argument) { ShiftOut display(D7, D8, D4); // clk=D7, data=D8, latch=D4, 16) uint8_t segment_data[4] = {0xFF, 0xFF, 0xFF, 0xFF}; // A frissítendő szegmenskép /* Számjegyek (0 – 9) szegmensképe, negatív logikával */ const uint8_t SEGMENT_MAP[]= {0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90}; /* Számjegy (1 - 4) kiválasztó jelek */ const uint8_t SEGMENT_SELECT[] = {0x01, 0x02, 0x04, 0x08}; uint8_t i, idx = 0; while (true) { osEvent evt = queue.get(0); // Check for a message without waiting switch(evt.status) { case osEventMessage: printf("osEventMessage = %#05x\n",evt.value.v); //message arrived int n = evt.value.v; segment_data[0] = SEGMENT_MAP[(n/1000) %10]; segment_data[1] = SEGMENT_MAP[(n/100) % 10]; segment_data[2] = SEGMENT_MAP[(n/10) % 10]; segment_data[3] = SEGMENT_MAP[n % 10]; break; case osOK: //--- pc.printf("osOK\n"); //no error, no message arrived i = idx++ & 0x03; display.write(segment_data[i]); display.write(SEGMENT_SELECT[i]); break; case osEventTimeout: pc.printf("osEventTimeout\n"); //timeout occurred break; case osErrorParameter: pc.printf("osErrorParameter\n"); break; //invalid parameter or is out of range. default: pc.printf("Unknown error flag: %#08x\n",(uint32_t)evt.status); break; }; Thread::wait(2); } } int main (void) { uint16_t raw; Thread thread2(display_thread); pc.baud(115200); buzzer = true; while (true) { Thread::wait(1000); raw++; queue.put((message_t*)raw); } }