Tom Soulanille / RTOS-Serial

An RTOS-friendly Serial interface Its primary benefit is that it never hogs the CPU. An amusing alternative to the traditional ring-bufferd interrupt-serviced systems, it uses short mbed-rtos queues to buffer characters to and from the UART, and a thread to service the transmitter. Short interrupt service routines enqueue received characters and signal the transmit thread when the transmitter is available. WARNING: Do not create RTOS-Serial objects before the RTOS is running! Put them inside your main() block or another function, not in the global initialization.

Dependents:   Test_RDM880_rfid_reader

rtos_serial.cpp@4:c7113cd0ac4b, 2013-10-19 (annotated)

Committer:
altasoul
Date:
Sat Oct 19 05:40:43 2013 +0000
Revision:
4:c7113cd0ac4b
Parent:
3:5865277b7710
Child:
5:5d388d1d7987
queue-buffered getc()

Who changed what in which revision?

UserRevisionLine numberNew contents of line
altasoul 0:0547c8bf304f 1 /*
altasoul 0:0547c8bf304f 2 * Copyright (c) 2013 Tom Soulanille
altasoul 0:0547c8bf304f 3 *
altasoul 0:0547c8bf304f 4 * Permission is hereby granted, free of charge, to any person obtaining a copy
altasoul 0:0547c8bf304f 5 * of this software and associated documentation files (the "Software"), to deal
altasoul 0:0547c8bf304f 6 * in the Software without restriction, including without limitation the rights
altasoul 0:0547c8bf304f 7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
altasoul 0:0547c8bf304f 8 * copies of the Software, and to permit persons to whom the Software is
altasoul 0:0547c8bf304f 9 * furnished to do so, subject to the following conditions:
altasoul 0:0547c8bf304f 10 *
altasoul 0:0547c8bf304f 11 * The above copyright notice and this permission notice shall be included in
altasoul 0:0547c8bf304f 12 * all copies or substantial portions of the Software.
altasoul 0:0547c8bf304f 13 *
altasoul 0:0547c8bf304f 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
altasoul 0:0547c8bf304f 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
altasoul 0:0547c8bf304f 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
altasoul 0:0547c8bf304f 17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
altasoul 0:0547c8bf304f 18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
altasoul 0:0547c8bf304f 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
altasoul 0:0547c8bf304f 20 * SOFTWARE.
altasoul 0:0547c8bf304f 21 */
altasoul 0:0547c8bf304f 22
altasoul 0:0547c8bf304f 23 #include "rtos_serial.h"
altasoul 0:0547c8bf304f 24
altasoul 0:0547c8bf304f 25 RTOS_Serial::RTOS_Serial(PinName tx, PinName rx, const char *name)
altasoul 0:0547c8bf304f 26 : Serial(tx, rx, name)
altasoul 0:0547c8bf304f 27 {
altasoul 0:0547c8bf304f 28 const PinName leds[] = {LED1,LED2,LED3,LED4};
altasoul 0:0547c8bf304f 29 ledp = new DigitalOut(leds[get_index()]);
altasoul 4:c7113cd0ac4b 30 rtos_serial_pointers_by_index[get_index()] = this;
altasoul 0:0547c8bf304f 31 tx_emitter_threadp = new Thread(tx_emitter, (void *) this);
altasoul 1:5a66fddad7c4 32 tx_tp[get_index()] = tx_emitter_threadp;
altasoul 4:c7113cd0ac4b 33 attach(rx_isr[get_index()], RxIrq);
altasoul 4:c7113cd0ac4b 34 attach(tx_isr[get_index()], TxIrq);
altasoul 2:891773cc33fd 35 tx_emitter_threadp->signal_set(0x01); // "prime the pump" of the tx-ready signals
altasoul 1:5a66fddad7c4 36 }
altasoul 0:0547c8bf304f 37
altasoul 4:c7113cd0ac4b 38 RTOS_Serial* RTOS_Serial::rtos_serial_pointers_by_index[4] = { NULL, NULL, NULL, NULL };
altasoul 2:891773cc33fd 39
altasoul 1:5a66fddad7c4 40 serial_t RTOS_Serial::get_serial() { return _serial; }
altasoul 0:0547c8bf304f 41
altasoul 0:0547c8bf304f 42 int RTOS_Serial::get_index() { return _serial.index; }
altasoul 0:0547c8bf304f 43
altasoul 0:0547c8bf304f 44 int RTOS_Serial::putc(int c) {
altasoul 2:891773cc33fd 45 //return Serial::putc(c); //DEBUG
altasoul 0:0547c8bf304f 46 //if (tx_q.put((int *)c, osWaitForever) == osOK) return c; else return EOF;
altasoul 0:0547c8bf304f 47 int status;
altasoul 0:0547c8bf304f 48 if ( (status = tx_q.put((int *)c, osWaitForever)) == osOK) return c; else {
altasoul 0:0547c8bf304f 49 std::printf("tx_q.put() returned %d\r\n", status);
altasoul 0:0547c8bf304f 50 return EOF;
altasoul 0:0547c8bf304f 51 }
altasoul 0:0547c8bf304f 52 }
altasoul 0:0547c8bf304f 53
altasoul 2:891773cc33fd 54 int RTOS_Serial::puts(const char *s) {
altasoul 2:891773cc33fd 55 int rv = 0;
altasoul 2:891773cc33fd 56 while (*s) {
altasoul 2:891773cc33fd 57 if (putc(*s++) == EOF) {
altasoul 2:891773cc33fd 58 rv = EOF;
altasoul 2:891773cc33fd 59 break;
altasoul 2:891773cc33fd 60 } else {
altasoul 2:891773cc33fd 61 rv++;
altasoul 2:891773cc33fd 62 }
altasoul 2:891773cc33fd 63 }
altasoul 2:891773cc33fd 64 return rv;
altasoul 2:891773cc33fd 65 }
altasoul 2:891773cc33fd 66
altasoul 0:0547c8bf304f 67 int RTOS_Serial::parent_putc(int c) {
altasoul 0:0547c8bf304f 68 return Serial::putc(c);
altasoul 0:0547c8bf304f 69 }
altasoul 0:0547c8bf304f 70
altasoul 2:891773cc33fd 71 int RTOS_Serial::getc() {
altasoul 4:c7113cd0ac4b 72 int rv;
altasoul 4:c7113cd0ac4b 73 //return Serial::getc(); //FIXME: stand-in, which fails if we use our RX ISR
altasoul 4:c7113cd0ac4b 74 osEvent evt = rx_q.get();
altasoul 4:c7113cd0ac4b 75 if (evt.status == osEventMessage) {
altasoul 4:c7113cd0ac4b 76 rv = (int) evt.value.v;
altasoul 4:c7113cd0ac4b 77 } else { //FIXME: find appropriate error reporting if any
altasoul 4:c7113cd0ac4b 78 std::printf("rx_dequeuer() evt.status %d\n", evt.status);
altasoul 4:c7113cd0ac4b 79 rv = EOF;
altasoul 4:c7113cd0ac4b 80 }
altasoul 4:c7113cd0ac4b 81 return rv;
altasoul 2:891773cc33fd 82 }
altasoul 2:891773cc33fd 83
altasoul 2:891773cc33fd 84
altasoul 2:891773cc33fd 85 // ISR's for transmitter interrupts
altasoul 0:0547c8bf304f 86 // class method
altasoul 0:0547c8bf304f 87 void RTOS_Serial::UART0_TX_ISR(){
altasoul 2:891773cc33fd 88 //uint32_t IRR = LPC_UART0->IIR;
altasoul 0:0547c8bf304f 89 //tx_emitter_threadp->signal_set(0x1);
altasoul 0:0547c8bf304f 90 tx_tp[0]->signal_set(0x01);
altasoul 0:0547c8bf304f 91 }
altasoul 1:5a66fddad7c4 92 // class method
altasoul 1:5a66fddad7c4 93 void RTOS_Serial::UART1_TX_ISR(){
altasoul 2:891773cc33fd 94 //uint32_t IRR = LPC_UART1->IIR;
altasoul 1:5a66fddad7c4 95 //tx_emitter_threadp->signal_set(0x1);
altasoul 1:5a66fddad7c4 96 tx_tp[1]->signal_set(0x01);
altasoul 1:5a66fddad7c4 97 }
altasoul 1:5a66fddad7c4 98 // class method
altasoul 1:5a66fddad7c4 99 void RTOS_Serial::UART2_TX_ISR(){
altasoul 2:891773cc33fd 100 //uint32_t IRR = LPC_UART2->IIR;
altasoul 1:5a66fddad7c4 101 //tx_emitter_threadp->signal_set(0x1);
altasoul 1:5a66fddad7c4 102 tx_tp[2]->signal_set(0x01);
altasoul 1:5a66fddad7c4 103 }
altasoul 1:5a66fddad7c4 104 // class method
altasoul 1:5a66fddad7c4 105 void RTOS_Serial::UART3_TX_ISR(){
altasoul 2:891773cc33fd 106 //uint32_t IRR = LPC_UART3->IIR;
altasoul 1:5a66fddad7c4 107 //tx_emitter_threadp->signal_set(0x1);
altasoul 1:5a66fddad7c4 108 tx_tp[3]->signal_set(0x01);
altasoul 1:5a66fddad7c4 109 }
altasoul 1:5a66fddad7c4 110
altasoul 1:5a66fddad7c4 111 func RTOS_Serial::tx_isr[4] = {
altasoul 1:5a66fddad7c4 112 &RTOS_Serial::UART0_TX_ISR,
altasoul 1:5a66fddad7c4 113 &RTOS_Serial::UART1_TX_ISR,
altasoul 1:5a66fddad7c4 114 &RTOS_Serial::UART2_TX_ISR,
altasoul 1:5a66fddad7c4 115 &RTOS_Serial::UART3_TX_ISR,
altasoul 1:5a66fddad7c4 116 };
altasoul 1:5a66fddad7c4 117
altasoul 2:891773cc33fd 118 /// ISR's for receiver interrupts
altasoul 2:891773cc33fd 119 // class method
altasoul 2:891773cc33fd 120 void RTOS_Serial::UART0_RX_ISR(){
altasoul 4:c7113cd0ac4b 121 RTOS_Serial::rtos_serial_pointers_by_index[0]->rx_q.put((int *)LPC_UART0->RBR);
altasoul 2:891773cc33fd 122 }
altasoul 2:891773cc33fd 123 // class method
altasoul 2:891773cc33fd 124 void RTOS_Serial::UART1_RX_ISR(){
altasoul 4:c7113cd0ac4b 125 RTOS_Serial::rtos_serial_pointers_by_index[1]->rx_q.put((int *)LPC_UART1->RBR);
altasoul 2:891773cc33fd 126 }
altasoul 2:891773cc33fd 127 // class method
altasoul 2:891773cc33fd 128 void RTOS_Serial::UART2_RX_ISR(){
altasoul 4:c7113cd0ac4b 129 RTOS_Serial::rtos_serial_pointers_by_index[2]->rx_q.put((int *)LPC_UART2->RBR);
altasoul 2:891773cc33fd 130 }
altasoul 2:891773cc33fd 131 // class method
altasoul 2:891773cc33fd 132 void RTOS_Serial::UART3_RX_ISR(){
altasoul 4:c7113cd0ac4b 133 RTOS_Serial::rtos_serial_pointers_by_index[3]->rx_q.put((int *)LPC_UART3->RBR);
altasoul 2:891773cc33fd 134 }
altasoul 2:891773cc33fd 135
altasoul 2:891773cc33fd 136 func RTOS_Serial::rx_isr[4] = {
altasoul 2:891773cc33fd 137 &RTOS_Serial::UART0_RX_ISR,
altasoul 2:891773cc33fd 138 &RTOS_Serial::UART1_RX_ISR,
altasoul 2:891773cc33fd 139 &RTOS_Serial::UART2_RX_ISR,
altasoul 2:891773cc33fd 140 &RTOS_Serial::UART3_RX_ISR,
altasoul 2:891773cc33fd 141 };
altasoul 2:891773cc33fd 142
altasoul 1:5a66fddad7c4 143 Thread* RTOS_Serial::tx_tp[4] = { NULL, NULL, NULL, NULL };
altasoul 0:0547c8bf304f 144
altasoul 0:0547c8bf304f 145 // tx_emitter is a class method
altasoul 0:0547c8bf304f 146 void RTOS_Serial::tx_emitter(void const *argument){
altasoul 0:0547c8bf304f 147 RTOS_Serial *sp = (RTOS_Serial *) argument;
altasoul 0:0547c8bf304f 148 osEvent evt;
altasoul 2:891773cc33fd 149 //osStatus status;
altasoul 0:0547c8bf304f 150 while(true){
altasoul 0:0547c8bf304f 151 evt = sp->tx_q.get();
altasoul 0:0547c8bf304f 152 if (evt.status == osEventMessage) {
altasoul 2:891773cc33fd 153 // There is no TX interrupt until the first byte is sent out the port,
altasoul 2:891773cc33fd 154 // so we use a timeout on the signal from the interrupt service routine
altasoul 2:891773cc33fd 155 // and just proceed to transmit the character. This should happen only
altasoul 2:891773cc33fd 156 // once at most, to "prime the pump", but the timeout provides some
altasoul 2:891773cc33fd 157 // safety in case something goes wrong.
altasoul 2:891773cc33fd 158 // A first signal is sent by the RTOS_Serial constructor when the thread
altasoul 2:891773cc33fd 159 // is created, so normally this will not come into effect.
altasoul 2:891773cc33fd 160 // DEBUG: timeout omitted to search for instabilities
altasoul 2:891773cc33fd 161 Thread::signal_wait(0x1/*, 10*/); //FIXME: base the timeout on the baud rate
altasoul 0:0547c8bf304f 162 *(sp->ledp) = 1;
altasoul 0:0547c8bf304f 163 sp->parent_putc(evt.value.v);
altasoul 0:0547c8bf304f 164 *(sp->ledp) = 0;
altasoul 0:0547c8bf304f 165 } else {
altasoul 0:0547c8bf304f 166 std::printf("tx_emitter() evt.status %d\n", evt.status);
altasoul 0:0547c8bf304f 167 }
altasoul 0:0547c8bf304f 168 *(sp->ledp) = 0;
altasoul 0:0547c8bf304f 169 }
altasoul 3:5865277b7710 170 }