ethan hong / MODSERIAL

USBUART - IRQ

Dependents:   MPU9250AHRS_UBSUART-IRQ

Fork of MODSERIAL by Andy K

example1.cpp@12:8c7394e2ae7f, 2011-01-20 (annotated)

Committer:
AjK
Date:
Thu Jan 20 11:57:32 2011 +0000
Revision:
12:8c7394e2ae7f
Child:
18:21ef26402365
1.12 See ChangeLog

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AjK 12:8c7394e2ae7f 1 #ifdef COMPILE_EXAMPLE1_CODE_MODSERIAL
AjK 12:8c7394e2ae7f 2
AjK 12:8c7394e2ae7f 3 /*
AjK 12:8c7394e2ae7f 4 * To run this test program, link p9 to p10 so the Serial loops
AjK 12:8c7394e2ae7f 5 * back and receives characters it sends.
AjK 12:8c7394e2ae7f 6 */
AjK 12:8c7394e2ae7f 7
AjK 12:8c7394e2ae7f 8 #include "mbed.h"
AjK 12:8c7394e2ae7f 9 #include "MODSERIAL.h"
AjK 12:8c7394e2ae7f 10
AjK 12:8c7394e2ae7f 11 DigitalOut led1(LED1);
AjK 12:8c7394e2ae7f 12 DigitalOut led2(LED2);
AjK 12:8c7394e2ae7f 13 DigitalOut led3(LED3);
AjK 12:8c7394e2ae7f 14 DigitalOut led4(LED4);
AjK 12:8c7394e2ae7f 15
AjK 12:8c7394e2ae7f 16 MODSERIAL pc(USBTX, USBRX);
AjK 12:8c7394e2ae7f 17
AjK 12:8c7394e2ae7f 18 /*
AjK 12:8c7394e2ae7f 19 * As experiement, you can define MODSERIAL as show here and see what
AjK 12:8c7394e2ae7f 20 * effects it has on the LEDs.
AjK 12:8c7394e2ae7f 21 *
AjK 12:8c7394e2ae7f 22 * MODSERIAL uart(TX_PIN, RX_PIN, 512);
AjK 12:8c7394e2ae7f 23 * With this, the 512 characters sent can straight into the buffer
AjK 12:8c7394e2ae7f 24 * vary quickly. This means LED1 is only on briefly as the TX buffer
AjK 12:8c7394e2ae7f 25 * fills.
AjK 12:8c7394e2ae7f 26 *
AjK 12:8c7394e2ae7f 27 * MODSERIAL uart(TX_PIN, RX_PIN, 32);
AjK 12:8c7394e2ae7f 28 * With this, the buffer is smaller than the default 256 bytes and
AjK 12:8c7394e2ae7f 29 * therefore LED1 stays on much longer while the system waits for
AjK 12:8c7394e2ae7f 30 * room in the TX buffer.
AjK 12:8c7394e2ae7f 31 */
AjK 12:8c7394e2ae7f 32 MODSERIAL uart(TX_PIN, RX_PIN);
AjK 12:8c7394e2ae7f 33
AjK 12:8c7394e2ae7f 34 // This function is called when a character goes from the TX buffer
AjK 12:8c7394e2ae7f 35 // to the Uart THR FIFO register.
AjK 12:8c7394e2ae7f 36 void txCallback(void) {
AjK 12:8c7394e2ae7f 37 led2 = !led2;
AjK 12:8c7394e2ae7f 38 }
AjK 12:8c7394e2ae7f 39
AjK 12:8c7394e2ae7f 40 // This function is called when TX buffer goes empty
AjK 12:8c7394e2ae7f 41 void txEmpty(void) {
AjK 12:8c7394e2ae7f 42 led2 = 0;
AjK 12:8c7394e2ae7f 43 pc.puts(" Done. ");
AjK 12:8c7394e2ae7f 44 }
AjK 12:8c7394e2ae7f 45
AjK 12:8c7394e2ae7f 46 // This function is called when a character goes into the RX buffer.
AjK 12:8c7394e2ae7f 47 void rxCallback(void) {
AjK 12:8c7394e2ae7f 48 led3 = !led3;
AjK 12:8c7394e2ae7f 49 pc.putc(uart.getc());
AjK 12:8c7394e2ae7f 50 }
AjK 12:8c7394e2ae7f 51
AjK 12:8c7394e2ae7f 52 int main() {
AjK 12:8c7394e2ae7f 53 int c = 'A';
AjK 12:8c7394e2ae7f 54
AjK 12:8c7394e2ae7f 55 // Ensure the baud rate for the PC "USB" serial is much
AjK 12:8c7394e2ae7f 56 // higher than "uart" baud rate below.
AjK 12:8c7394e2ae7f 57 pc.baud(PC_BAUD);
AjK 12:8c7394e2ae7f 58
AjK 12:8c7394e2ae7f 59 // Use a deliberatly slow baud to fill up the TX buffer
AjK 12:8c7394e2ae7f 60 uart.baud(1200);
AjK 12:8c7394e2ae7f 61
AjK 12:8c7394e2ae7f 62 uart.attach(&txCallback, MODSERIAL::TxIrq);
AjK 12:8c7394e2ae7f 63 uart.attach(&rxCallback, MODSERIAL::RxIrq);
AjK 12:8c7394e2ae7f 64 uart.attach(&txEmpty, MODSERIAL::TxEmpty);
AjK 12:8c7394e2ae7f 65
AjK 12:8c7394e2ae7f 66 // Loop sending characters. We send 512
AjK 12:8c7394e2ae7f 67 // which is twice the default TX/RX buffer size.
AjK 12:8c7394e2ae7f 68
AjK 12:8c7394e2ae7f 69 led1 = 1; // Show start of sending with LED1.
AjK 12:8c7394e2ae7f 70
AjK 12:8c7394e2ae7f 71 for (int loop = 0; loop < 512; loop++) {
AjK 12:8c7394e2ae7f 72 uart.printf("%c", c);
AjK 12:8c7394e2ae7f 73 c++;
AjK 12:8c7394e2ae7f 74 if (c > 'Z') c = 'A';
AjK 12:8c7394e2ae7f 75 }
AjK 12:8c7394e2ae7f 76
AjK 12:8c7394e2ae7f 77 led1 = 0; // Show the end of sending by switching off LED1.
AjK 12:8c7394e2ae7f 78
AjK 12:8c7394e2ae7f 79 // End program. Flash LED4. Notice how LED 2 and 3 continue
AjK 12:8c7394e2ae7f 80 // to flash for a short period while the interrupt system
AjK 12:8c7394e2ae7f 81 // continues to send the characters left in the TX buffer.
AjK 12:8c7394e2ae7f 82
AjK 12:8c7394e2ae7f 83 while(1) {
AjK 12:8c7394e2ae7f 84 led4 = !led4;
AjK 12:8c7394e2ae7f 85 wait(0.25);
AjK 12:8c7394e2ae7f 86 }
AjK 12:8c7394e2ae7f 87 }
AjK 12:8c7394e2ae7f 88
AjK 12:8c7394e2ae7f 89 /*
AjK 12:8c7394e2ae7f 90 * Notes. Here is the sort of output you can expect on your PC/Mac/Linux host
AjK 12:8c7394e2ae7f 91 * machine that is connected to the "pc" USB serial port.
AjK 12:8c7394e2ae7f 92 *
AjK 12:8c7394e2ae7f 93 * ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUV
AjK 12:8c7394e2ae7f 94 * WXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQR
AjK 12:8c7394e2ae7f 95 * STUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMN
AjK 12:8c7394e2ae7f 96 * OPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJ
AjK 12:8c7394e2ae7f 97 * KLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEF
AjK 12:8c7394e2ae7f 98 * GHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB
AjK 12:8c7394e2ae7f 99 * CDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R
AjK 12:8c7394e2ae7f 100 *
AjK 12:8c7394e2ae7f 101 * Of interest is that last "R" character after the system has said "Done."
AjK 12:8c7394e2ae7f 102 * This comes from the fact that the TxEmpty callback is made when the TX buffer
AjK 12:8c7394e2ae7f 103 * becomes empty. MODSERIAL makes use of the fact that the Uarts built into the
AjK 12:8c7394e2ae7f 104 * LPC17xx device use a 16 byte FIFO on both RX and TX channels. This means that
AjK 12:8c7394e2ae7f 105 * when the TxEmpty callback is made, the TX buffer is empty, but that just means
AjK 12:8c7394e2ae7f 106 * the "last few characters" were written to the TX FIFO. So although the TX
AjK 12:8c7394e2ae7f 107 * buffer has gone empty, the Uart's transmit system is still sending any remaining
AjK 12:8c7394e2ae7f 108 * characters from it's TX FIFO. If you want to be truely sure all the characters
AjK 12:8c7394e2ae7f 109 * you have sent have left the Mbed then call txIsBusy(); This function will
AjK 12:8c7394e2ae7f 110 * return true if characters are still being sent. If it returns false after
AjK 12:8c7394e2ae7f 111 * the Tx buffer is empty then all your characters have been sent.
AjK 12:8c7394e2ae7f 112 *
AjK 12:8c7394e2ae7f 113 * In a similar way, when characters are received into the RX FIFO, the entire
AjK 12:8c7394e2ae7f 114 * FIFO contents is moved to the RX buffer, assuming there is room left in the
AjK 12:8c7394e2ae7f 115 * RX buffer. If there is not, any remaining characters are left in the RX FIFO
AjK 12:8c7394e2ae7f 116 * and will be moved to the RX buffer on the next interrupt or when the running
AjK 12:8c7394e2ae7f 117 * program removes a character(s) from the RX buffer with the getc() method.
AjK 12:8c7394e2ae7f 118 */
AjK 12:8c7394e2ae7f 119
AjK 12:8c7394e2ae7f 120 #endif