Modserial
Fork of MODSERIAL by
example1.cpp
- Committer:
- AjK
- Date:
- 2011-04-21
- Revision:
- 18:21ef26402365
- Parent:
- 12:8c7394e2ae7f
- Child:
- 27:9c93ce7cb9d8
File content as of revision 18:21ef26402365:
#ifdef COMPILE_EXAMPLE1_CODE_MODSERIAL /* * To run this test program, link p9 to p10 so the Serial loops * back and receives characters it sends. */ #include "mbed.h" #include "MODSERIAL.h" 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); // This function is called when a character goes from the TX buffer // to the Uart THR FIFO register. void txCallback(MODSERIAL_IRQ_INFO *q) { led2 = !led2; } // This function is called when TX buffer goes empty void txEmpty(MODSERIAL_IRQ_INFO *q) { led2 = 0; pc.puts(" Done. "); } // This function is called when a character goes into the RX buffer. void rxCallback(MODSERIAL_IRQ_INFO *q) { led3 = !led3; pc.putc(uart.getc()); } int main() { int c = 'A'; // 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 = 1; // Show start of sending with LED1. 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. * * ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUV * WXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQR * STUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMN * OPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJ * KLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEF * GHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZAB * CDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQ Done. R * * 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