Diff: example_dma.cpp

Revision:

30:b04ce87dc424

Parent:

29:9a41078f0488

Child:

31:b90b20f78f04

diff -r 9a41078f0488 -r b04ce87dc424 example_dma.cpp
--- a/example_dma.cpp	Fri Jul 12 15:56:20 2013 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,144 +0,0 @@
-#ifdef COMPILE_EXAMPLE_CODE_MODSERIAL_MODDMA
-
-/*
- * To run this test program, link p9 to p10 so the Serial loops
- * back and receives characters it sends.
- */
- 
-#include "mbed.h"
-
-/* Note, this example requires that you also import into the Mbed
-   compiler the MODDMA project as well as MODSERIAL
-   http://mbed.org/users/AjK/libraries/MODDMA/latest 
-   MODDMA.h MUST come before MODSERIAL.h */
-#include "MODDMA.h"     // <--- Declare first
-#include "MODSERIAL.h"  // Flollowed by MODSERIAL
-
-DigitalOut led1(LED1);
-DigitalOut led2(LED2);
-DigitalOut led3(LED3);
-DigitalOut led4(LED4);
-
-MODSERIAL pc(USBTX, USBRX);
-
-/*
- * As experiement, you can define MODSERIAL as show here and see what
- * effects it has on the LEDs.
- *
- * MODSERIAL uart(TX_PIN, RX_PIN, 512);
- *   With this, the 512 characters sent can straight into the buffer
- *   vary quickly. This means LED1 is only on briefly as the TX buffer
- *   fills.
- *
- * MODSERIAL uart(TX_PIN, RX_PIN, 32);
- *   With this, the buffer is smaller than the default 256 bytes and
- *   therefore LED1 stays on much longer while the system waits for
- *   room in the TX buffer.
- */
-MODSERIAL uart(TX_PIN, RX_PIN);
-
-MODDMA dma;
-
-// This function is called when a character goes from the TX buffer
-// to the Uart THR FIFO register.
-void txCallback(void) {
-    led2 = !led2;
-}
-
-// This function is called when TX buffer goes empty
-void txEmpty(void) {
-    led2 = 0;
-    pc.puts(" Done. ");
-}
-
-void dmaComplete(void) {
-    led1 = 1;
-}
-
-// This function is called when a character goes into the RX buffer.
-void rxCallback(void) {
-    led3 = !led3;
-    pc.putc(uart.getc());
-}
-
-int main() {
-    char s1[] = " *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* ";
-    int c = 'A';
-    
-    // Tell MODSERIAL where the MODDMA controller is.
-    pc.MODDMA( &dma );
-    
-    // Ensure the baud rate for the PC "USB" serial is much
-    // higher than "uart" baud rate below.
-    pc.baud( PC_BAUD );
-    
-    // Use a deliberatly slow baud to fill up the TX buffer
-    uart.baud(1200);
-    
-    uart.attach( &txCallback, MODSERIAL::TxIrq );
-    uart.attach( &rxCallback, MODSERIAL::RxIrq );
-    uart.attach( &txEmpty,    MODSERIAL::TxEmpty );
-    
-    // Loop sending characters. We send 512
-    // which is twice the default TX/RX buffer size.
-    
-    led1 = 0;
-    
-    // Send the buffer s using DMA channel 7
-    pc.attach_dmaSendComplete( &dmaComplete );
-    pc.dmaSend( s1, sizeof(s1), MODDMA::Channel_7 );
-    
-    for (int loop = 0; loop < 512; loop++) {
-        uart.printf("%c", c);        
-        c++;
-        if (c > 'Z') c = 'A';
-    }
-    
-    led1 = 0; // Show the end of sending by switching off LED1.
-    
-    // End program. Flash LED4. Notice how LED 2 and 3 continue
-    // to flash for a short period while the interrupt system 
-    // continues to send the characters left in the TX buffer.
-    
-    while(1) {
-        led4 = !led4;
-        wait(0.25);
-    }
-}
-
-/*
- * Notes. Here is the sort of output you can expect on your PC/Mac/Linux host
- * machine that is connected to the "pc" USB serial port.
- *
- *  *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* ABCDEFGHIJKLMNOPQRSTUVWXYZABCDE
- * FGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZA
- * BCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVW
- * XYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRS
- * TUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNO
- * PQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJK
- * LMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFG
- * HIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R
- *
- * Note how the DMA blocks the TX buffer sending under standard interrupt control.
- * Not until the DMA transfer is complete will "normal" buffered TX sending resume.
- *
- * Of interest is that last "R" character after the system has said "Done."
- * This comes from the fact that the TxEmpty callback is made when the TX buffer
- * becomes empty. MODSERIAL makes use of the fact that the Uarts built into the 
- * LPC17xx device use a 16 byte FIFO on both RX and TX channels. This means that
- * when the TxEmpty callback is made, the TX buffer is empty, but that just means
- * the "last few characters" were written to the TX FIFO. So although the TX
- * buffer has gone empty, the Uart's transmit system is still sending any remaining
- * characters from it's TX FIFO. If you want to be truely sure all the characters
- * you have sent have left the Mbed then call txIsBusy(); This function will
- * return true if characters are still being sent. If it returns false after
- * the Tx buffer is empty then all your characters have been sent.
- *
- * In a similar way, when characters are received into the RX FIFO, the entire
- * FIFO contents is moved to the RX buffer, assuming there is room left in the
- * RX buffer. If there is not, any remaining characters are left in the RX FIFO
- * and will be moved to the RX buffer on the next interrupt or when the running 
- * program removes a character(s) from the RX buffer with the getc() method.
- */
- 
-#endif