main.cpp

00001 #include "mbed.h"
00002 #include "rtos.h"
00003 #include "SimpleDMA.h"
00004 
00005 DigitalOut led1(LED1);
00006 SimpleDMA dma(0);
00007 RawSerial pc(USBTX, USBRX);
00008 
00009 void callback(void) {
00010     pc.printf("Callback!\r\n");
00011     }
00012 
00013 void led_thread(void const *args) {
00014     
00015     while (true) {
00016         led1 = !led1;
00017         Thread::wait(300);
00018     }
00019 }
00020 
00021 
00022 int main() {
00023     printf("Start\r\n");
00024     
00025     printf("Use DMA to send 10 characters from buffer to buffer\r\n");
00026     printf("Then send them to UART0 (PC)\r\n");
00027     
00028     char characters[] = "abcdefgh\r\n";     //Characters we send
00029     char characters2[11];                   //Second buffer
00030     
00031     //Set source and destination, second argument is true since
00032     //we should run through both arrays
00033     dma.source(characters, true);
00034     dma.destination(characters2, true);
00035     //dma.attach(callback);
00036     //Start transfer of 10 characters
00037     dma.start(10);
00038     
00039     while(dma.isBusy());
00040     
00041     //Now to UART, enable DMA in UART, destination is now
00042     //a fixed address, so address pointer should not be incremented,
00043     //thus second argument is false. Also set trigger to UART0_RX.
00044     //This sends a new value to the UART as soon as it is possible
00045     #ifdef TARGET_LPC1768
00046     LPC_UART0->FCR |= 1<<3;
00047     dma.destination(&LPC_UART0->THR, false);
00048     #endif
00049     #ifdef TARGET_KL25Z
00050     UART0->C5 |= (1<<7) | (1<<5);
00051     dma.destination(&UART0->D, false);
00052     #endif
00053     dma.source(characters2, true);
00054     dma.trigger(Trigger_UART0_TX);
00055 
00056     dma.start(10);
00057     while(dma.isBusy());      
00058     
00059     printf("\r\n\nNow to show if it doesn't increment the address\r\n");
00060     printf("Also we attach a callback\r\n");
00061     dma.source(characters2, false);
00062     dma.attach(callback);
00063     dma.start(10);
00064     while(dma.isBusy());  
00065 
00066     
00067     printf("\r\n\nFinally we make it a loopback, and use RTOS\r\n");
00068     printf("The LED in another thread continues blinking while DMA send is busy\r\n");
00069     
00070     //Make a thread with low priority, to show main thread with DMA gives way to other thread while busy sending
00071     Thread thread(led_thread);
00072     thread.set_priority(osPriorityLow);
00073     
00074     #ifdef TARGET_LPC1768
00075     dma.source(&LPC_UART0->THR, false);
00076     #endif
00077     #ifdef TARGET_KL25Z
00078     dma.source(&UART0->D, false);
00079     #endif
00080     
00081     //Trigger is now the receiving on the UART
00082     dma.trigger(Trigger_UART0_RX);
00083     
00084     //dma.wait blocks the current Thread until finished while allowing other threads to run
00085     dma.wait(10);
00086     
00087     printf("\r\n\nFinished :-)\r\n");
00088     
00089     //Notice the LED doesn't blink now, since this thread uses all resources in while(1)
00090     while(1);
00091 }