Erik - / Mbed 2 deprecated SimpleDMA_HelloWorld

HelloWorld program showing SimpleDMA with mainly UART stuff

Dependencies:   SimpleDMA mbed-rtos mbed

main.cpp@0:cf18a31facd6, 2013-12-26 (annotated)

Committer:
Sissors
Date:
Thu Dec 26 16:32:59 2013 +0000
Revision:
0:cf18a31facd6
Child:
1:418889681f13
v1.0

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Who changed what in which revision?

UserRevisionLine numberNew contents of line
Sissors 0:cf18a31facd6 1 #include "mbed.h"
Sissors 0:cf18a31facd6 2 #include "rtos.h"
Sissors 0:cf18a31facd6 3 #include "SimpleDMA.h"
Sissors 0:cf18a31facd6 4
Sissors 0:cf18a31facd6 5 DigitalOut led1(LED1);
Sissors 0:cf18a31facd6 6 SimpleDMA dma;
Sissors 0:cf18a31facd6 7 RawSerial pc(USBTX, USBRX);
Sissors 0:cf18a31facd6 8
Sissors 0:cf18a31facd6 9 void callback(void) {
Sissors 0:cf18a31facd6 10 pc.printf("Callback!\r\n");
Sissors 0:cf18a31facd6 11 }
Sissors 0:cf18a31facd6 12
Sissors 0:cf18a31facd6 13 void led_thread(void const *args) {
Sissors 0:cf18a31facd6 14
Sissors 0:cf18a31facd6 15 while (true) {
Sissors 0:cf18a31facd6 16 led1 = !led1;
Sissors 0:cf18a31facd6 17 Thread::wait(300);
Sissors 0:cf18a31facd6 18 }
Sissors 0:cf18a31facd6 19 }
Sissors 0:cf18a31facd6 20
Sissors 0:cf18a31facd6 21
Sissors 0:cf18a31facd6 22 int main() {
Sissors 0:cf18a31facd6 23 printf("Start\r\n");
Sissors 0:cf18a31facd6 24
Sissors 0:cf18a31facd6 25 printf("Use DMA to send 10 characters from buffer to buffer\r\n");
Sissors 0:cf18a31facd6 26 printf("Then send them to UART0 (PC)\r\n");
Sissors 0:cf18a31facd6 27
Sissors 0:cf18a31facd6 28 char characters[] = "abcdefgh\r\n"; //Characters we send
Sissors 0:cf18a31facd6 29 char characters2[11]; //Second buffer
Sissors 0:cf18a31facd6 30
Sissors 0:cf18a31facd6 31 //Set source and destination, second argument is true since
Sissors 0:cf18a31facd6 32 //we should run through both arrays
Sissors 0:cf18a31facd6 33 dma.source(characters, true);
Sissors 0:cf18a31facd6 34 dma.destination(characters2, true);
Sissors 0:cf18a31facd6 35 //dma.attach(callback);
Sissors 0:cf18a31facd6 36 //Start transfer of 10 characters
Sissors 0:cf18a31facd6 37 dma.start(10);
Sissors 0:cf18a31facd6 38
Sissors 0:cf18a31facd6 39 while(dma.isBusy());
Sissors 0:cf18a31facd6 40
Sissors 0:cf18a31facd6 41 //Now to UART, enable DMA in UART, destination is now
Sissors 0:cf18a31facd6 42 //a fixed address, so address pointer should not be incremented,
Sissors 0:cf18a31facd6 43 //thus second argument is false. Also set trigger to UART0_RX.
Sissors 0:cf18a31facd6 44 //This sends a new value to the UART as soon as it is possible
Sissors 0:cf18a31facd6 45 UART0->C5 |= (1<<7) | (1<<5);
Sissors 0:cf18a31facd6 46 dma.source(characters2, true);
Sissors 0:cf18a31facd6 47 dma.destination(&UART0->D, false);
Sissors 0:cf18a31facd6 48 dma.trigger(Trigger_UART0_TX);
Sissors 0:cf18a31facd6 49
Sissors 0:cf18a31facd6 50 dma.start(10);
Sissors 0:cf18a31facd6 51 while(dma.isBusy());
Sissors 0:cf18a31facd6 52
Sissors 0:cf18a31facd6 53 printf("\r\n\nNow to show if it doesn't increment the address\r\n");
Sissors 0:cf18a31facd6 54 printf("Also we attach a callback\r\n");
Sissors 0:cf18a31facd6 55 dma.source(characters2, false);
Sissors 0:cf18a31facd6 56 dma.attach(callback);
Sissors 0:cf18a31facd6 57 dma.start(10);
Sissors 0:cf18a31facd6 58 while(dma.isBusy());
Sissors 0:cf18a31facd6 59
Sissors 0:cf18a31facd6 60
Sissors 0:cf18a31facd6 61 printf("\r\n\nFinally we make it a loopback, and use RTOS\r\n");
Sissors 0:cf18a31facd6 62 printf("The LED in another thread continues blinking while DMA send is busy\r\n");
Sissors 0:cf18a31facd6 63
Sissors 0:cf18a31facd6 64 //Make a thread with low priority, to show main thread with DMA gives way to other thread while busy sending
Sissors 0:cf18a31facd6 65 Thread thread(led_thread);
Sissors 0:cf18a31facd6 66 thread.set_priority(osPriorityLow);
Sissors 0:cf18a31facd6 67
Sissors 0:cf18a31facd6 68 dma.source(&UART0->D, false);
Sissors 0:cf18a31facd6 69 //Trigger is now the receiving on the UART
Sissors 0:cf18a31facd6 70 dma.trigger(Trigger_UART0_RX);
Sissors 0:cf18a31facd6 71
Sissors 0:cf18a31facd6 72 //dma.wait blocks the current Thread until finished while allowing other threads to run
Sissors 0:cf18a31facd6 73 dma.wait(10);
Sissors 0:cf18a31facd6 74
Sissors 0:cf18a31facd6 75 printf("\r\n\nFinished :-)\r\n");
Sissors 0:cf18a31facd6 76
Sissors 0:cf18a31facd6 77 //Notice the LED doesn't blink now, since this thread uses all resources in while(1)
Sissors 0:cf18a31facd6 78 while(1);
Sissors 0:cf18a31facd6 79 }