Marco Mayer / Mbed OS Queue

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mbed-os/features/unsupported/tests/mbed/modserial/main.cpp@0:6bf0743ece18, 2020-03-28 (annotated)

Committer:
demayer
Date:
Sat Mar 28 15:28:19 2020 +0000
Revision:
0:6bf0743ece18
IMU Thread with an event-queue running parallel to handle tasks like a 5 times blinking LED. Button with interrupt detected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
demayer 0:6bf0743ece18 1 /*
demayer 0:6bf0743ece18 2 * To run this test program, link p9 to p10 so the Serial loops
demayer 0:6bf0743ece18 3 * back and receives characters it sends.
demayer 0:6bf0743ece18 4 */
demayer 0:6bf0743ece18 5 #include "mbed.h"
demayer 0:6bf0743ece18 6 #include "MODSERIAL.h"
demayer 0:6bf0743ece18 7
demayer 0:6bf0743ece18 8 DigitalOut led1(LED1);
demayer 0:6bf0743ece18 9 DigitalOut led2(LED2);
demayer 0:6bf0743ece18 10 DigitalOut led3(LED3);
demayer 0:6bf0743ece18 11 DigitalOut led4(LED4);
demayer 0:6bf0743ece18 12
demayer 0:6bf0743ece18 13 MODSERIAL pc(USBTX, USBRX);
demayer 0:6bf0743ece18 14
demayer 0:6bf0743ece18 15 /*
demayer 0:6bf0743ece18 16 * As experiement, you can define MODSERIAL as show here and see what
demayer 0:6bf0743ece18 17 * effects it has on the LEDs.
demayer 0:6bf0743ece18 18 *
demayer 0:6bf0743ece18 19 * MODSERIAL uart(TX_PIN, RX_PIN, 512);
demayer 0:6bf0743ece18 20 * With this, the 512 characters sent can straight into the buffer
demayer 0:6bf0743ece18 21 * vary quickly. This means LED1 is only on briefly as the TX buffer
demayer 0:6bf0743ece18 22 * fills.
demayer 0:6bf0743ece18 23 *
demayer 0:6bf0743ece18 24 * MODSERIAL uart(TX_PIN, RX_PIN, 32);
demayer 0:6bf0743ece18 25 * With this, the buffer is smaller than the default 256 bytes and
demayer 0:6bf0743ece18 26 * therefore LED1 stays on much longer while the system waits for
demayer 0:6bf0743ece18 27 * room in the TX buffer.
demayer 0:6bf0743ece18 28 */
demayer 0:6bf0743ece18 29 MODSERIAL uart(p9, p10);
demayer 0:6bf0743ece18 30
demayer 0:6bf0743ece18 31 // This function is called when a character goes from the TX buffer
demayer 0:6bf0743ece18 32 // to the Uart THR FIFO register.
demayer 0:6bf0743ece18 33 void txCallback(MODSERIAL_IRQ_INFO *q) {
demayer 0:6bf0743ece18 34 led2 = !led2;
demayer 0:6bf0743ece18 35 }
demayer 0:6bf0743ece18 36
demayer 0:6bf0743ece18 37 // This function is called when TX buffer goes empty
demayer 0:6bf0743ece18 38 void txEmpty(MODSERIAL_IRQ_INFO *q) {
demayer 0:6bf0743ece18 39 led2 = 0;
demayer 0:6bf0743ece18 40 pc.puts(" Done. ");
demayer 0:6bf0743ece18 41 }
demayer 0:6bf0743ece18 42
demayer 0:6bf0743ece18 43 // This function is called when a character goes into the RX buffer.
demayer 0:6bf0743ece18 44 void rxCallback(MODSERIAL_IRQ_INFO *q) {
demayer 0:6bf0743ece18 45 led3 = !led3;
demayer 0:6bf0743ece18 46 pc.putc(uart.getc());
demayer 0:6bf0743ece18 47 }
demayer 0:6bf0743ece18 48
demayer 0:6bf0743ece18 49 int main() {
demayer 0:6bf0743ece18 50 int c = 'A';
demayer 0:6bf0743ece18 51
demayer 0:6bf0743ece18 52 // Ensure the baud rate for the PC "USB" serial is much
demayer 0:6bf0743ece18 53 // higher than "uart" baud rate below. (default: 9600)
demayer 0:6bf0743ece18 54 // pc.baud(9600);
demayer 0:6bf0743ece18 55
demayer 0:6bf0743ece18 56 // Use a deliberatly slow baud to fill up the TX buffer
demayer 0:6bf0743ece18 57 uart.baud(1200);
demayer 0:6bf0743ece18 58
demayer 0:6bf0743ece18 59 uart.attach(&txCallback, MODSERIAL::ModTxIrq);
demayer 0:6bf0743ece18 60 uart.attach(&rxCallback, MODSERIAL::ModRxIrq);
demayer 0:6bf0743ece18 61 uart.attach(&txEmpty, MODSERIAL::ModTxEmpty);
demayer 0:6bf0743ece18 62
demayer 0:6bf0743ece18 63 // Loop sending characters. We send 512
demayer 0:6bf0743ece18 64 // which is twice the default TX/RX buffer size.
demayer 0:6bf0743ece18 65
demayer 0:6bf0743ece18 66 led1 = 1; // Show start of sending with LED1.
demayer 0:6bf0743ece18 67
demayer 0:6bf0743ece18 68 for (int loop = 0; loop < 512; loop++) {
demayer 0:6bf0743ece18 69 uart.printf("%c", c);
demayer 0:6bf0743ece18 70 c++;
demayer 0:6bf0743ece18 71 if (c > 'Z') c = 'A';
demayer 0:6bf0743ece18 72 }
demayer 0:6bf0743ece18 73
demayer 0:6bf0743ece18 74 led1 = 0; // Show the end of sending by switching off LED1.
demayer 0:6bf0743ece18 75
demayer 0:6bf0743ece18 76 // End program. Flash LED4. Notice how LED 2 and 3 continue
demayer 0:6bf0743ece18 77 // to flash for a short period while the interrupt system
demayer 0:6bf0743ece18 78 // continues to send the characters left in the TX buffer.
demayer 0:6bf0743ece18 79
demayer 0:6bf0743ece18 80 while(1) {
demayer 0:6bf0743ece18 81 led4 = !led4;
demayer 0:6bf0743ece18 82 wait(0.25);
demayer 0:6bf0743ece18 83 }
demayer 0:6bf0743ece18 84 }
demayer 0:6bf0743ece18 85
demayer 0:6bf0743ece18 86 /*
demayer 0:6bf0743ece18 87 * Notes. Here is the sort of output you can expect on your PC/Mac/Linux host
demayer 0:6bf0743ece18 88 * machine that is connected to the "pc" USB serial port.
demayer 0:6bf0743ece18 89 *
demayer 0:6bf0743ece18 90 * ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUV
demayer 0:6bf0743ece18 91 * WXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQR
demayer 0:6bf0743ece18 92 * STUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMN
demayer 0:6bf0743ece18 93 * OPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJ
demayer 0:6bf0743ece18 94 * KLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEF
demayer 0:6bf0743ece18 95 * GHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB
demayer 0:6bf0743ece18 96 * CDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R
demayer 0:6bf0743ece18 97 *
demayer 0:6bf0743ece18 98 * Of interest is that last "R" character after the system has said "Done."
demayer 0:6bf0743ece18 99 * This comes from the fact that the TxEmpty callback is made when the TX buffer
demayer 0:6bf0743ece18 100 * becomes empty. MODSERIAL makes use of the fact that the Uarts built into the
demayer 0:6bf0743ece18 101 * LPC17xx device use a 16 byte FIFO on both RX and TX channels. This means that
demayer 0:6bf0743ece18 102 * when the TxEmpty callback is made, the TX buffer is empty, but that just means
demayer 0:6bf0743ece18 103 * the "last few characters" were written to the TX FIFO. So although the TX
demayer 0:6bf0743ece18 104 * buffer has gone empty, the Uart's transmit system is still sending any remaining
demayer 0:6bf0743ece18 105 * characters from it's TX FIFO. If you want to be truely sure all the characters
demayer 0:6bf0743ece18 106 * you have sent have left the Mbed then call txIsBusy(); This function will
demayer 0:6bf0743ece18 107 * return true if characters are still being sent. If it returns false after
demayer 0:6bf0743ece18 108 * the Tx buffer is empty then all your characters have been sent.
demayer 0:6bf0743ece18 109 *
demayer 0:6bf0743ece18 110 * In a similar way, when characters are received into the RX FIFO, the entire
demayer 0:6bf0743ece18 111 * FIFO contents is moved to the RX buffer, assuming there is room left in the
demayer 0:6bf0743ece18 112 * RX buffer. If there is not, any remaining characters are left in the RX FIFO
demayer 0:6bf0743ece18 113 * and will be moved to the RX buffer on the next interrupt or when the running
demayer 0:6bf0743ece18 114 * program removes a character(s) from the RX buffer with the getc() method.
demayer 0:6bf0743ece18 115 */