Derek Fukumori / MODSERIAL

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Fork of MODSERIAL by Andy K

example1.cpp@23:1236d0b64e71, 2012-07-13 (annotated)

Committer:
dfukumori
Date:
Fri Jul 13 01:09:23 2012 +0000
Revision:
23:1236d0b64e71
Parent:
18:21ef26402365 
Required commit -- no changes

Who changed what in which revision?

UserRevisionLine numberNew contents of line
dfukumori 23:1236d0b64e71 1 #ifdef COMPILE_EXAMPLE1_CODE_MODSERIAL
dfukumori 23:1236d0b64e71 2
dfukumori 23:1236d0b64e71 3 /*
dfukumori 23:1236d0b64e71 4 * To run this test program, link p9 to p10 so the Serial loops
dfukumori 23:1236d0b64e71 5 * back and receives characters it sends.
dfukumori 23:1236d0b64e71 6 */
dfukumori 23:1236d0b64e71 7
dfukumori 23:1236d0b64e71 8 #include "mbed.h"
dfukumori 23:1236d0b64e71 9 #include "MODSERIAL.h"
dfukumori 23:1236d0b64e71 10
dfukumori 23:1236d0b64e71 11 DigitalOut led1(LED1);
dfukumori 23:1236d0b64e71 12 DigitalOut led2(LED2);
dfukumori 23:1236d0b64e71 13 DigitalOut led3(LED3);
dfukumori 23:1236d0b64e71 14 DigitalOut led4(LED4);
dfukumori 23:1236d0b64e71 15
dfukumori 23:1236d0b64e71 16 MODSERIAL pc(USBTX, USBRX);
dfukumori 23:1236d0b64e71 17
dfukumori 23:1236d0b64e71 18 /*
dfukumori 23:1236d0b64e71 19 * As experiement, you can define MODSERIAL as show here and see what
dfukumori 23:1236d0b64e71 20 * effects it has on the LEDs.
dfukumori 23:1236d0b64e71 21 *
dfukumori 23:1236d0b64e71 22 * MODSERIAL uart(TX_PIN, RX_PIN, 512);
dfukumori 23:1236d0b64e71 23 * With this, the 512 characters sent can straight into the buffer
dfukumori 23:1236d0b64e71 24 * vary quickly. This means LED1 is only on briefly as the TX buffer
dfukumori 23:1236d0b64e71 25 * fills.
dfukumori 23:1236d0b64e71 26 *
dfukumori 23:1236d0b64e71 27 * MODSERIAL uart(TX_PIN, RX_PIN, 32);
dfukumori 23:1236d0b64e71 28 * With this, the buffer is smaller than the default 256 bytes and
dfukumori 23:1236d0b64e71 29 * therefore LED1 stays on much longer while the system waits for
dfukumori 23:1236d0b64e71 30 * room in the TX buffer.
dfukumori 23:1236d0b64e71 31 */
dfukumori 23:1236d0b64e71 32 MODSERIAL uart(TX_PIN, RX_PIN);
dfukumori 23:1236d0b64e71 33
dfukumori 23:1236d0b64e71 34 // This function is called when a character goes from the TX buffer
dfukumori 23:1236d0b64e71 35 // to the Uart THR FIFO register.
dfukumori 23:1236d0b64e71 36 void txCallback(MODSERIAL_IRQ_INFO *q) {
dfukumori 23:1236d0b64e71 37 led2 = !led2;
dfukumori 23:1236d0b64e71 38 }
dfukumori 23:1236d0b64e71 39
dfukumori 23:1236d0b64e71 40 // This function is called when TX buffer goes empty
dfukumori 23:1236d0b64e71 41 void txEmpty(MODSERIAL_IRQ_INFO *q) {
dfukumori 23:1236d0b64e71 42 led2 = 0;
dfukumori 23:1236d0b64e71 43 pc.puts(" Done. ");
dfukumori 23:1236d0b64e71 44 }
dfukumori 23:1236d0b64e71 45
dfukumori 23:1236d0b64e71 46 // This function is called when a character goes into the RX buffer.
dfukumori 23:1236d0b64e71 47 void rxCallback(MODSERIAL_IRQ_INFO *q) {
dfukumori 23:1236d0b64e71 48 led3 = !led3;
dfukumori 23:1236d0b64e71 49 pc.putc(uart.getc());
dfukumori 23:1236d0b64e71 50 }
dfukumori 23:1236d0b64e71 51
dfukumori 23:1236d0b64e71 52 int main() {
dfukumori 23:1236d0b64e71 53 int c = 'A';
dfukumori 23:1236d0b64e71 54
dfukumori 23:1236d0b64e71 55 // Ensure the baud rate for the PC "USB" serial is much
dfukumori 23:1236d0b64e71 56 // higher than "uart" baud rate below.
dfukumori 23:1236d0b64e71 57 pc.baud(PC_BAUD);
dfukumori 23:1236d0b64e71 58
dfukumori 23:1236d0b64e71 59 // Use a deliberatly slow baud to fill up the TX buffer
dfukumori 23:1236d0b64e71 60 uart.baud(1200);
dfukumori 23:1236d0b64e71 61
dfukumori 23:1236d0b64e71 62 uart.attach(&txCallback, MODSERIAL::TxIrq);
dfukumori 23:1236d0b64e71 63 uart.attach(&rxCallback, MODSERIAL::RxIrq);
dfukumori 23:1236d0b64e71 64 uart.attach(&txEmpty, MODSERIAL::TxEmpty);
dfukumori 23:1236d0b64e71 65
dfukumori 23:1236d0b64e71 66 // Loop sending characters. We send 512
dfukumori 23:1236d0b64e71 67 // which is twice the default TX/RX buffer size.
dfukumori 23:1236d0b64e71 68
dfukumori 23:1236d0b64e71 69 led1 = 1; // Show start of sending with LED1.
dfukumori 23:1236d0b64e71 70
dfukumori 23:1236d0b64e71 71 for (int loop = 0; loop < 512; loop++) {
dfukumori 23:1236d0b64e71 72 uart.printf("%c", c);
dfukumori 23:1236d0b64e71 73 c++;
dfukumori 23:1236d0b64e71 74 if (c > 'Z') c = 'A';
dfukumori 23:1236d0b64e71 75 }
dfukumori 23:1236d0b64e71 76
dfukumori 23:1236d0b64e71 77 led1 = 0; // Show the end of sending by switching off LED1.
dfukumori 23:1236d0b64e71 78
dfukumori 23:1236d0b64e71 79 // End program. Flash LED4. Notice how LED 2 and 3 continue
dfukumori 23:1236d0b64e71 80 // to flash for a short period while the interrupt system
dfukumori 23:1236d0b64e71 81 // continues to send the characters left in the TX buffer.
dfukumori 23:1236d0b64e71 82
dfukumori 23:1236d0b64e71 83 while(1) {
dfukumori 23:1236d0b64e71 84 led4 = !led4;
dfukumori 23:1236d0b64e71 85 wait(0.25);
dfukumori 23:1236d0b64e71 86 }
dfukumori 23:1236d0b64e71 87 }
dfukumori 23:1236d0b64e71 88
dfukumori 23:1236d0b64e71 89 /*
dfukumori 23:1236d0b64e71 90 * Notes. Here is the sort of output you can expect on your PC/Mac/Linux host
dfukumori 23:1236d0b64e71 91 * machine that is connected to the "pc" USB serial port.
dfukumori 23:1236d0b64e71 92 *
dfukumori 23:1236d0b64e71 93 * ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUV
dfukumori 23:1236d0b64e71 94 * WXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQR
dfukumori 23:1236d0b64e71 95 * STUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMN
dfukumori 23:1236d0b64e71 96 * OPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJ
dfukumori 23:1236d0b64e71 97 * KLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEF
dfukumori 23:1236d0b64e71 98 * GHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB
dfukumori 23:1236d0b64e71 99 * CDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R
dfukumori 23:1236d0b64e71 100 *
dfukumori 23:1236d0b64e71 101 * Of interest is that last "R" character after the system has said "Done."
dfukumori 23:1236d0b64e71 102 * This comes from the fact that the TxEmpty callback is made when the TX buffer
dfukumori 23:1236d0b64e71 103 * becomes empty. MODSERIAL makes use of the fact that the Uarts built into the
dfukumori 23:1236d0b64e71 104 * LPC17xx device use a 16 byte FIFO on both RX and TX channels. This means that
dfukumori 23:1236d0b64e71 105 * when the TxEmpty callback is made, the TX buffer is empty, but that just means
dfukumori 23:1236d0b64e71 106 * the "last few characters" were written to the TX FIFO. So although the TX
dfukumori 23:1236d0b64e71 107 * buffer has gone empty, the Uart's transmit system is still sending any remaining
dfukumori 23:1236d0b64e71 108 * characters from it's TX FIFO. If you want to be truely sure all the characters
dfukumori 23:1236d0b64e71 109 * you have sent have left the Mbed then call txIsBusy(); This function will
dfukumori 23:1236d0b64e71 110 * return true if characters are still being sent. If it returns false after
dfukumori 23:1236d0b64e71 111 * the Tx buffer is empty then all your characters have been sent.
dfukumori 23:1236d0b64e71 112 *
dfukumori 23:1236d0b64e71 113 * In a similar way, when characters are received into the RX FIFO, the entire
dfukumori 23:1236d0b64e71 114 * FIFO contents is moved to the RX buffer, assuming there is room left in the
dfukumori 23:1236d0b64e71 115 * RX buffer. If there is not, any remaining characters are left in the RX FIFO
dfukumori 23:1236d0b64e71 116 * and will be moved to the RX buffer on the next interrupt or when the running
dfukumori 23:1236d0b64e71 117 * program removes a character(s) from the RX buffer with the getc() method.
dfukumori 23:1236d0b64e71 118 */
dfukumori 23:1236d0b64e71 119
dfukumori 23:1236d0b64e71 120 #endif