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Andy Kirkham / MODSERIAL Featured
Last commit 08 Jan 2013 tag buffer, Buffered, rs232, RS485, Serial

Description: Bug fix release

example_dma.cpp@12:8c7394e2ae7f, 20 Jan 2011 (annotated)

Committer:
user Andy Kirkham
Date:
Thu Jan 20 11:57:32 2011 +0000
Revision:
12:8c7394e2ae7f
Parent:
11:a93a62eeeb9d
1.12 See ChangeLog

Who changed what in which revision?

UserRevisionLine numberNew contents of line
user Andy Kirkham12:8c7394e2ae7f 1#ifdef COMPILE_EXAMPLE_CODE_MODSERIAL_MODDMA
user Andy Kirkham12:8c7394e2ae7f 2
user Andy Kirkham12:8c7394e2ae7f 3/*
user Andy Kirkham12:8c7394e2ae7f 4 * To run this test program, link p9 to p10 so the Serial loops
user Andy Kirkham12:8c7394e2ae7f 5 * back and receives characters it sends.
user Andy Kirkham12:8c7394e2ae7f 6 */
user Andy Kirkham12:8c7394e2ae7f 7
user Andy Kirkham12:8c7394e2ae7f 8#include "mbed.h"
user Andy Kirkham12:8c7394e2ae7f 9
user Andy Kirkham12:8c7394e2ae7f 10/* Note, this example requires that you also import into the Mbed
user Andy Kirkham12:8c7394e2ae7f 11 compiler the MODDMA project as well as MODSERIAL
user Andy Kirkham12:8c7394e2ae7f 12 http://mbed.org/users/AjK/libraries/MODDMA/latest
user Andy Kirkham12:8c7394e2ae7f 13 MODDMA.h MUST come before MODSERIAL.h */
user Andy Kirkham12:8c7394e2ae7f 14#include "MODDMA.h" // <--- Declare first
user Andy Kirkham12:8c7394e2ae7f 15#include "MODSERIAL.h" // Flollowed by MODSERIAL
user Andy Kirkham12:8c7394e2ae7f 16
user Andy Kirkham12:8c7394e2ae7f 17DigitalOut led1(LED1);
user Andy Kirkham12:8c7394e2ae7f 18DigitalOut led2(LED2);
user Andy Kirkham12:8c7394e2ae7f 19DigitalOut led3(LED3);
user Andy Kirkham12:8c7394e2ae7f 20DigitalOut led4(LED4);
user Andy Kirkham12:8c7394e2ae7f 21
user Andy Kirkham12:8c7394e2ae7f 22MODSERIAL pc(USBTX, USBRX);
user Andy Kirkham12:8c7394e2ae7f 23
user Andy Kirkham12:8c7394e2ae7f 24/*
user Andy Kirkham12:8c7394e2ae7f 25 * As experiement, you can define MODSERIAL as show here and see what
user Andy Kirkham12:8c7394e2ae7f 26 * effects it has on the LEDs.
user Andy Kirkham12:8c7394e2ae7f 27 *
user Andy Kirkham12:8c7394e2ae7f 28 * MODSERIAL uart(TX_PIN, RX_PIN, 512);
user Andy Kirkham12:8c7394e2ae7f 29 * With this, the 512 characters sent can straight into the buffer
user Andy Kirkham12:8c7394e2ae7f 30 * vary quickly. This means LED1 is only on briefly as the TX buffer
user Andy Kirkham12:8c7394e2ae7f 31 * fills.
user Andy Kirkham12:8c7394e2ae7f 32 *
user Andy Kirkham12:8c7394e2ae7f 33 * MODSERIAL uart(TX_PIN, RX_PIN, 32);
user Andy Kirkham12:8c7394e2ae7f 34 * With this, the buffer is smaller than the default 256 bytes and
user Andy Kirkham12:8c7394e2ae7f 35 * therefore LED1 stays on much longer while the system waits for
user Andy Kirkham12:8c7394e2ae7f 36 * room in the TX buffer.
user Andy Kirkham12:8c7394e2ae7f 37 */
user Andy Kirkham12:8c7394e2ae7f 38MODSERIAL uart(TX_PIN, RX_PIN);
user Andy Kirkham12:8c7394e2ae7f 39
user Andy Kirkham12:8c7394e2ae7f 40MODDMA dma;
user Andy Kirkham12:8c7394e2ae7f 41
user Andy Kirkham12:8c7394e2ae7f 42// This function is called when a character goes from the TX buffer
user Andy Kirkham12:8c7394e2ae7f 43// to the Uart THR FIFO register.
user Andy Kirkham12:8c7394e2ae7f 44void txCallback(void) {
user Andy Kirkham12:8c7394e2ae7f 45 led2 = !led2;
user Andy Kirkham12:8c7394e2ae7f 46}
user Andy Kirkham12:8c7394e2ae7f 47
user Andy Kirkham12:8c7394e2ae7f 48// This function is called when TX buffer goes empty
user Andy Kirkham12:8c7394e2ae7f 49void txEmpty(void) {
user Andy Kirkham12:8c7394e2ae7f 50 led2 = 0;
user Andy Kirkham12:8c7394e2ae7f 51 pc.puts(" Done. ");
user Andy Kirkham12:8c7394e2ae7f 52}
user Andy Kirkham12:8c7394e2ae7f 53
user Andy Kirkham12:8c7394e2ae7f 54void dmaComplete(void) {
user Andy Kirkham12:8c7394e2ae7f 55 led1 = 1;
user Andy Kirkham12:8c7394e2ae7f 56}
user Andy Kirkham12:8c7394e2ae7f 57
user Andy Kirkham12:8c7394e2ae7f 58// This function is called when a character goes into the RX buffer.
user Andy Kirkham12:8c7394e2ae7f 59void rxCallback(void) {
user Andy Kirkham12:8c7394e2ae7f 60 led3 = !led3;
user Andy Kirkham12:8c7394e2ae7f 61 pc.putc(uart.getc());
user Andy Kirkham12:8c7394e2ae7f 62}
user Andy Kirkham12:8c7394e2ae7f 63
user Andy Kirkham12:8c7394e2ae7f 64int main() {
user Andy Kirkham12:8c7394e2ae7f 65 char s1[] = " *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* ";
user Andy Kirkham12:8c7394e2ae7f 66 int c = 'A';
user Andy Kirkham12:8c7394e2ae7f 67
user Andy Kirkham12:8c7394e2ae7f 68 // Tell MODSERIAL where the MODDMA controller is.
user Andy Kirkham12:8c7394e2ae7f 69 pc.MODDMA( &dma );
user Andy Kirkham12:8c7394e2ae7f 70
user Andy Kirkham12:8c7394e2ae7f 71 // Ensure the baud rate for the PC "USB" serial is much
user Andy Kirkham12:8c7394e2ae7f 72 // higher than "uart" baud rate below.
user Andy Kirkham12:8c7394e2ae7f 73 pc.baud( PC_BAUD );
user Andy Kirkham12:8c7394e2ae7f 74
user Andy Kirkham12:8c7394e2ae7f 75 // Use a deliberatly slow baud to fill up the TX buffer
user Andy Kirkham12:8c7394e2ae7f 76 uart.baud(1200);
user Andy Kirkham12:8c7394e2ae7f 77
user Andy Kirkham12:8c7394e2ae7f 78 uart.attach( &txCallback, MODSERIAL::TxIrq );
user Andy Kirkham12:8c7394e2ae7f 79 uart.attach( &rxCallback, MODSERIAL::RxIrq );
user Andy Kirkham12:8c7394e2ae7f 80 uart.attach( &txEmpty, MODSERIAL::TxEmpty );
user Andy Kirkham12:8c7394e2ae7f 81
user Andy Kirkham12:8c7394e2ae7f 82 // Loop sending characters. We send 512
user Andy Kirkham12:8c7394e2ae7f 83 // which is twice the default TX/RX buffer size.
user Andy Kirkham12:8c7394e2ae7f 84
user Andy Kirkham12:8c7394e2ae7f 85 led1 = 0;
user Andy Kirkham12:8c7394e2ae7f 86
user Andy Kirkham12:8c7394e2ae7f 87 // Send the buffer s using DMA channel 7
user Andy Kirkham12:8c7394e2ae7f 88 pc.attach_dmaSendComplete( &dmaComplete );
user Andy Kirkham12:8c7394e2ae7f 89 pc.dmaSend( s1, sizeof(s1), MODDMA::Channel_7 );
user Andy Kirkham12:8c7394e2ae7f 90
user Andy Kirkham12:8c7394e2ae7f 91 for (int loop = 0; loop < 512; loop++) {
user Andy Kirkham12:8c7394e2ae7f 92 uart.printf("%c", c);
user Andy Kirkham12:8c7394e2ae7f 93 c++;
user Andy Kirkham12:8c7394e2ae7f 94 if (c > 'Z') c = 'A';
user Andy Kirkham12:8c7394e2ae7f 95 }
user Andy Kirkham12:8c7394e2ae7f 96
user Andy Kirkham12:8c7394e2ae7f 97 led1 = 0; // Show the end of sending by switching off LED1.
user Andy Kirkham12:8c7394e2ae7f 98
user Andy Kirkham12:8c7394e2ae7f 99 // End program. Flash LED4. Notice how LED 2 and 3 continue
user Andy Kirkham12:8c7394e2ae7f 100 // to flash for a short period while the interrupt system
user Andy Kirkham12:8c7394e2ae7f 101 // continues to send the characters left in the TX buffer.
user Andy Kirkham12:8c7394e2ae7f 102
user Andy Kirkham12:8c7394e2ae7f 103 while(1) {
user Andy Kirkham12:8c7394e2ae7f 104 led4 = !led4;
user Andy Kirkham12:8c7394e2ae7f 105 wait(0.25);
user Andy Kirkham12:8c7394e2ae7f 106 }
user Andy Kirkham12:8c7394e2ae7f 107}
user Andy Kirkham12:8c7394e2ae7f 108
user Andy Kirkham12:8c7394e2ae7f 109/*
user Andy Kirkham12:8c7394e2ae7f 110 * Notes. Here is the sort of output you can expect on your PC/Mac/Linux host
user Andy Kirkham12:8c7394e2ae7f 111 * machine that is connected to the "pc" USB serial port.
user Andy Kirkham12:8c7394e2ae7f 112 *
user Andy Kirkham12:8c7394e2ae7f 113 * *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* *DMA* ABCDEFGHIJKLMNOPQRSTUVWXYZABCDE
user Andy Kirkham12:8c7394e2ae7f 114 * FGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZA
user Andy Kirkham12:8c7394e2ae7f 115 * BCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVW
user Andy Kirkham12:8c7394e2ae7f 116 * XYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRS
user Andy Kirkham12:8c7394e2ae7f 117 * TUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNO
user Andy Kirkham12:8c7394e2ae7f 118 * PQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJK
user Andy Kirkham12:8c7394e2ae7f 119 * LMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFG
user Andy Kirkham12:8c7394e2ae7f 120 * HIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R
user Andy Kirkham12:8c7394e2ae7f 121 *
user Andy Kirkham12:8c7394e2ae7f 122 * Note how the DMA blocks the TX buffer sending under standard interrupt control.
user Andy Kirkham12:8c7394e2ae7f 123 * Not until the DMA transfer is complete will "normal" buffered TX sending resume.
user Andy Kirkham12:8c7394e2ae7f 124 *
user Andy Kirkham12:8c7394e2ae7f 125 * Of interest is that last "R" character after the system has said "Done."
user Andy Kirkham12:8c7394e2ae7f 126 * This comes from the fact that the TxEmpty callback is made when the TX buffer
user Andy Kirkham12:8c7394e2ae7f 127 * becomes empty. MODSERIAL makes use of the fact that the Uarts built into the
user Andy Kirkham12:8c7394e2ae7f 128 * LPC17xx device use a 16 byte FIFO on both RX and TX channels. This means that
user Andy Kirkham12:8c7394e2ae7f 129 * when the TxEmpty callback is made, the TX buffer is empty, but that just means
user Andy Kirkham12:8c7394e2ae7f 130 * the "last few characters" were written to the TX FIFO. So although the TX
user Andy Kirkham12:8c7394e2ae7f 131 * buffer has gone empty, the Uart's transmit system is still sending any remaining
user Andy Kirkham12:8c7394e2ae7f 132 * characters from it's TX FIFO. If you want to be truely sure all the characters
user Andy Kirkham12:8c7394e2ae7f 133 * you have sent have left the Mbed then call txIsBusy(); This function will
user Andy Kirkham12:8c7394e2ae7f 134 * return true if characters are still being sent. If it returns false after
user Andy Kirkham12:8c7394e2ae7f 135 * the Tx buffer is empty then all your characters have been sent.
user Andy Kirkham12:8c7394e2ae7f 136 *
user Andy Kirkham12:8c7394e2ae7f 137 * In a similar way, when characters are received into the RX FIFO, the entire
user Andy Kirkham12:8c7394e2ae7f 138 * FIFO contents is moved to the RX buffer, assuming there is room left in the
user Andy Kirkham12:8c7394e2ae7f 139 * RX buffer. If there is not, any remaining characters are left in the RX FIFO
user Andy Kirkham12:8c7394e2ae7f 140 * and will be moved to the RX buffer on the next interrupt or when the running
user Andy Kirkham12:8c7394e2ae7f 141 * program removes a character(s) from the RX buffer with the getc() method.
user Andy Kirkham12:8c7394e2ae7f 142 */
user Andy Kirkham12:8c7394e2ae7f 143
user Andy Kirkham12:8c7394e2ae7f 144#endif