Marco Mayer / Mbed OS Queue

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mbed-os/targets/TARGET_NXP/TARGET_LPC13XX/serial_api.c@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 /* mbed Microcontroller Library
demayer 0:6bf0743ece18 2 * Copyright (c) 2006-2013 ARM Limited
demayer 0:6bf0743ece18 3 *
demayer 0:6bf0743ece18 4 * Licensed under the Apache License, Version 2.0 (the "License");
demayer 0:6bf0743ece18 5 * you may not use this file except in compliance with the License.
demayer 0:6bf0743ece18 6 * You may obtain a copy of the License at
demayer 0:6bf0743ece18 7 *
demayer 0:6bf0743ece18 8 * http://www.apache.org/licenses/LICENSE-2.0
demayer 0:6bf0743ece18 9 *
demayer 0:6bf0743ece18 10 * Unless required by applicable law or agreed to in writing, software
demayer 0:6bf0743ece18 11 * distributed under the License is distributed on an "AS IS" BASIS,
demayer 0:6bf0743ece18 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
demayer 0:6bf0743ece18 13 * See the License for the specific language governing permissions and
demayer 0:6bf0743ece18 14 * limitations under the License.
demayer 0:6bf0743ece18 15 */
demayer 0:6bf0743ece18 16 // math.h required for floating point operations for baud rate calculation
demayer 0:6bf0743ece18 17 #include "mbed_assert.h"
demayer 0:6bf0743ece18 18 #include <math.h>
demayer 0:6bf0743ece18 19 #include <string.h>
demayer 0:6bf0743ece18 20 #include <stdlib.h>
demayer 0:6bf0743ece18 21
demayer 0:6bf0743ece18 22 #include "serial_api.h"
demayer 0:6bf0743ece18 23 #include "cmsis.h"
demayer 0:6bf0743ece18 24 #include "pinmap.h"
demayer 0:6bf0743ece18 25
demayer 0:6bf0743ece18 26 /******************************************************************************
demayer 0:6bf0743ece18 27 * INITIALIZATION
demayer 0:6bf0743ece18 28 ******************************************************************************/
demayer 0:6bf0743ece18 29 #define UART_NUM 1
demayer 0:6bf0743ece18 30
demayer 0:6bf0743ece18 31 static const PinMap PinMap_UART_TX[] = {
demayer 0:6bf0743ece18 32 {P0_19, UART_0, 1},
demayer 0:6bf0743ece18 33 {P1_13, UART_0, 3},
demayer 0:6bf0743ece18 34 {P1_27, UART_0, 2},
demayer 0:6bf0743ece18 35 { NC , NC , 0}
demayer 0:6bf0743ece18 36 };
demayer 0:6bf0743ece18 37
demayer 0:6bf0743ece18 38 static const PinMap PinMap_UART_RX[] = {
demayer 0:6bf0743ece18 39 {P0_18, UART_0, 1},
demayer 0:6bf0743ece18 40 {P1_14, UART_0, 3},
demayer 0:6bf0743ece18 41 {P1_26, UART_0, 2},
demayer 0:6bf0743ece18 42 {NC , NC , 0}
demayer 0:6bf0743ece18 43 };
demayer 0:6bf0743ece18 44
demayer 0:6bf0743ece18 45 static uint32_t serial_irq_ids[UART_NUM] = {0};
demayer 0:6bf0743ece18 46 static uart_irq_handler irq_handler;
demayer 0:6bf0743ece18 47
demayer 0:6bf0743ece18 48 int stdio_uart_inited = 0;
demayer 0:6bf0743ece18 49 serial_t stdio_uart;
demayer 0:6bf0743ece18 50
demayer 0:6bf0743ece18 51 void serial_init(serial_t *obj, PinName tx, PinName rx) {
demayer 0:6bf0743ece18 52 int is_stdio_uart = 0;
demayer 0:6bf0743ece18 53
demayer 0:6bf0743ece18 54 // determine the UART to use
demayer 0:6bf0743ece18 55 UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
demayer 0:6bf0743ece18 56 UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
demayer 0:6bf0743ece18 57 UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
demayer 0:6bf0743ece18 58 MBED_ASSERT((int)uart != NC);
demayer 0:6bf0743ece18 59
demayer 0:6bf0743ece18 60 obj->uart = (LPC_USART_Type *)uart;
demayer 0:6bf0743ece18 61 LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
demayer 0:6bf0743ece18 62
demayer 0:6bf0743ece18 63 // [TODO] Consider more elegant approach
demayer 0:6bf0743ece18 64 // disconnect USBTX/RX mapping mux, for case when switching ports
demayer 0:6bf0743ece18 65 //pin_function(USBTX, 0);
demayer 0:6bf0743ece18 66 //pin_function(USBRX, 0);
demayer 0:6bf0743ece18 67
demayer 0:6bf0743ece18 68 // enable fifos and default rx trigger level
demayer 0:6bf0743ece18 69 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
demayer 0:6bf0743ece18 70 | 0 << 1 // Rx Fifo Reset
demayer 0:6bf0743ece18 71 | 0 << 2 // Tx Fifo Reset
demayer 0:6bf0743ece18 72 | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
demayer 0:6bf0743ece18 73
demayer 0:6bf0743ece18 74 // disable irqs
demayer 0:6bf0743ece18 75 obj->uart->IER = 0 << 0 // Rx Data available irq enable
demayer 0:6bf0743ece18 76 | 0 << 1 // Tx Fifo empty irq enable
demayer 0:6bf0743ece18 77 | 0 << 2; // Rx Line Status irq enable
demayer 0:6bf0743ece18 78
demayer 0:6bf0743ece18 79 // set default baud rate and format
demayer 0:6bf0743ece18 80 serial_baud (obj, 9600);
demayer 0:6bf0743ece18 81 serial_format(obj, 8, ParityNone, 1);
demayer 0:6bf0743ece18 82
demayer 0:6bf0743ece18 83 // pinout the chosen uart
demayer 0:6bf0743ece18 84 pinmap_pinout(tx, PinMap_UART_TX);
demayer 0:6bf0743ece18 85 pinmap_pinout(rx, PinMap_UART_RX);
demayer 0:6bf0743ece18 86
demayer 0:6bf0743ece18 87 // set rx/tx pins in PullUp mode
demayer 0:6bf0743ece18 88 if (tx != NC) {
demayer 0:6bf0743ece18 89 pin_mode(tx, PullUp);
demayer 0:6bf0743ece18 90 }
demayer 0:6bf0743ece18 91 if (rx != NC) {
demayer 0:6bf0743ece18 92 pin_mode(rx, PullUp);
demayer 0:6bf0743ece18 93 }
demayer 0:6bf0743ece18 94
demayer 0:6bf0743ece18 95 switch (uart) {
demayer 0:6bf0743ece18 96 case UART_0: obj->index = 0; break;
demayer 0:6bf0743ece18 97 }
demayer 0:6bf0743ece18 98
demayer 0:6bf0743ece18 99 is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
demayer 0:6bf0743ece18 100
demayer 0:6bf0743ece18 101 if (is_stdio_uart) {
demayer 0:6bf0743ece18 102 stdio_uart_inited = 1;
demayer 0:6bf0743ece18 103 memcpy(&stdio_uart, obj, sizeof(serial_t));
demayer 0:6bf0743ece18 104 }
demayer 0:6bf0743ece18 105 }
demayer 0:6bf0743ece18 106
demayer 0:6bf0743ece18 107 void serial_free(serial_t *obj) {
demayer 0:6bf0743ece18 108 serial_irq_ids[obj->index] = 0;
demayer 0:6bf0743ece18 109 }
demayer 0:6bf0743ece18 110
demayer 0:6bf0743ece18 111 // serial_baud
demayer 0:6bf0743ece18 112 // set the baud rate, taking in to account the current SystemFrequency
demayer 0:6bf0743ece18 113 void serial_baud(serial_t *obj, int baudrate) {
demayer 0:6bf0743ece18 114 LPC_SYSCON->UARTCLKDIV = 0x1;
demayer 0:6bf0743ece18 115 uint32_t PCLK = SystemCoreClock;
demayer 0:6bf0743ece18 116 // First we check to see if the basic divide with no DivAddVal/MulVal
demayer 0:6bf0743ece18 117 // ratio gives us an integer result. If it does, we set DivAddVal = 0,
demayer 0:6bf0743ece18 118 // MulVal = 1. Otherwise, we search the valid ratio value range to find
demayer 0:6bf0743ece18 119 // the closest match. This could be more elegant, using search methods
demayer 0:6bf0743ece18 120 // and/or lookup tables, but the brute force method is not that much
demayer 0:6bf0743ece18 121 // slower, and is more maintainable.
demayer 0:6bf0743ece18 122 uint16_t DL = PCLK / (16 * baudrate);
demayer 0:6bf0743ece18 123
demayer 0:6bf0743ece18 124 uint8_t DivAddVal = 0;
demayer 0:6bf0743ece18 125 uint8_t MulVal = 1;
demayer 0:6bf0743ece18 126 int hit = 0;
demayer 0:6bf0743ece18 127 uint16_t dlv;
demayer 0:6bf0743ece18 128 uint8_t mv, dav;
demayer 0:6bf0743ece18 129 if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
demayer 0:6bf0743ece18 130 int err_best = baudrate, b;
demayer 0:6bf0743ece18 131 for (mv = 1; mv < 16 && !hit; mv++)
demayer 0:6bf0743ece18 132 {
demayer 0:6bf0743ece18 133 for (dav = 0; dav < mv; dav++)
demayer 0:6bf0743ece18 134 {
demayer 0:6bf0743ece18 135 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
demayer 0:6bf0743ece18 136 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
demayer 0:6bf0743ece18 137 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
demayer 0:6bf0743ece18 138 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
demayer 0:6bf0743ece18 139 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
demayer 0:6bf0743ece18 140
demayer 0:6bf0743ece18 141 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
demayer 0:6bf0743ece18 142 dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
demayer 0:6bf0743ece18 143 else // 2 bits headroom, use more precision
demayer 0:6bf0743ece18 144 dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
demayer 0:6bf0743ece18 145
demayer 0:6bf0743ece18 146 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
demayer 0:6bf0743ece18 147 if (dlv == 0)
demayer 0:6bf0743ece18 148 dlv = 1;
demayer 0:6bf0743ece18 149
demayer 0:6bf0743ece18 150 // datasheet says if dav > 0 then DL must be >= 2
demayer 0:6bf0743ece18 151 if ((dav > 0) && (dlv < 2))
demayer 0:6bf0743ece18 152 dlv = 2;
demayer 0:6bf0743ece18 153
demayer 0:6bf0743ece18 154 // integer rearrangement of the baudrate equation (with rounding)
demayer 0:6bf0743ece18 155 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
demayer 0:6bf0743ece18 156
demayer 0:6bf0743ece18 157 // check to see how we went
demayer 0:6bf0743ece18 158 b = abs(b - baudrate);
demayer 0:6bf0743ece18 159 if (b < err_best)
demayer 0:6bf0743ece18 160 {
demayer 0:6bf0743ece18 161 err_best = b;
demayer 0:6bf0743ece18 162
demayer 0:6bf0743ece18 163 DL = dlv;
demayer 0:6bf0743ece18 164 MulVal = mv;
demayer 0:6bf0743ece18 165 DivAddVal = dav;
demayer 0:6bf0743ece18 166
demayer 0:6bf0743ece18 167 if (b == baudrate)
demayer 0:6bf0743ece18 168 {
demayer 0:6bf0743ece18 169 hit = 1;
demayer 0:6bf0743ece18 170 break;
demayer 0:6bf0743ece18 171 }
demayer 0:6bf0743ece18 172 }
demayer 0:6bf0743ece18 173 }
demayer 0:6bf0743ece18 174 }
demayer 0:6bf0743ece18 175 }
demayer 0:6bf0743ece18 176
demayer 0:6bf0743ece18 177 // set LCR[DLAB] to enable writing to divider registers
demayer 0:6bf0743ece18 178 obj->uart->LCR |= (1 << 7);
demayer 0:6bf0743ece18 179
demayer 0:6bf0743ece18 180 // set divider values
demayer 0:6bf0743ece18 181 obj->uart->DLM = (DL >> 8) & 0xFF;
demayer 0:6bf0743ece18 182 obj->uart->DLL = (DL >> 0) & 0xFF;
demayer 0:6bf0743ece18 183 obj->uart->FDR = (uint32_t) DivAddVal << 0
demayer 0:6bf0743ece18 184 | (uint32_t) MulVal << 4;
demayer 0:6bf0743ece18 185
demayer 0:6bf0743ece18 186 // clear LCR[DLAB]
demayer 0:6bf0743ece18 187 obj->uart->LCR &= ~(1 << 7);
demayer 0:6bf0743ece18 188 }
demayer 0:6bf0743ece18 189
demayer 0:6bf0743ece18 190 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
demayer 0:6bf0743ece18 191 MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
demayer 0:6bf0743ece18 192 MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
demayer 0:6bf0743ece18 193 MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
demayer 0:6bf0743ece18 194 (parity == ParityForced1) || (parity == ParityForced0));
demayer 0:6bf0743ece18 195
demayer 0:6bf0743ece18 196 stop_bits -= 1;
demayer 0:6bf0743ece18 197 data_bits -= 5;
demayer 0:6bf0743ece18 198
demayer 0:6bf0743ece18 199 int parity_enable, parity_select;
demayer 0:6bf0743ece18 200 switch (parity) {
demayer 0:6bf0743ece18 201 case ParityNone: parity_enable = 0; parity_select = 0; break;
demayer 0:6bf0743ece18 202 case ParityOdd : parity_enable = 1; parity_select = 0; break;
demayer 0:6bf0743ece18 203 case ParityEven: parity_enable = 1; parity_select = 1; break;
demayer 0:6bf0743ece18 204 case ParityForced1: parity_enable = 1; parity_select = 2; break;
demayer 0:6bf0743ece18 205 case ParityForced0: parity_enable = 1; parity_select = 3; break;
demayer 0:6bf0743ece18 206 default:
demayer 0:6bf0743ece18 207 break;
demayer 0:6bf0743ece18 208 }
demayer 0:6bf0743ece18 209
demayer 0:6bf0743ece18 210 obj->uart->LCR = data_bits << 0
demayer 0:6bf0743ece18 211 | stop_bits << 2
demayer 0:6bf0743ece18 212 | parity_enable << 3
demayer 0:6bf0743ece18 213 | parity_select << 4;
demayer 0:6bf0743ece18 214 }
demayer 0:6bf0743ece18 215
demayer 0:6bf0743ece18 216 /******************************************************************************
demayer 0:6bf0743ece18 217 * INTERRUPTS HANDLING
demayer 0:6bf0743ece18 218 ******************************************************************************/
demayer 0:6bf0743ece18 219 static inline void uart_irq(uint32_t iir, uint32_t index) {
demayer 0:6bf0743ece18 220 // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
demayer 0:6bf0743ece18 221 SerialIrq irq_type;
demayer 0:6bf0743ece18 222 switch (iir) {
demayer 0:6bf0743ece18 223 case 1: irq_type = TxIrq; break;
demayer 0:6bf0743ece18 224 case 2: irq_type = RxIrq; break;
demayer 0:6bf0743ece18 225 default: return;
demayer 0:6bf0743ece18 226 }
demayer 0:6bf0743ece18 227
demayer 0:6bf0743ece18 228 if (serial_irq_ids[index] != 0)
demayer 0:6bf0743ece18 229 irq_handler(serial_irq_ids[index], irq_type);
demayer 0:6bf0743ece18 230 }
demayer 0:6bf0743ece18 231
demayer 0:6bf0743ece18 232 void uart0_irq() {uart_irq((LPC_USART->IIR >> 1) & 0x7, 0);}
demayer 0:6bf0743ece18 233
demayer 0:6bf0743ece18 234 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
demayer 0:6bf0743ece18 235 irq_handler = handler;
demayer 0:6bf0743ece18 236 serial_irq_ids[obj->index] = id;
demayer 0:6bf0743ece18 237 }
demayer 0:6bf0743ece18 238
demayer 0:6bf0743ece18 239 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
demayer 0:6bf0743ece18 240 IRQn_Type irq_n = (IRQn_Type)0;
demayer 0:6bf0743ece18 241 uint32_t vector = 0;
demayer 0:6bf0743ece18 242 switch ((int)obj->uart) {
demayer 0:6bf0743ece18 243 case UART_0: irq_n=USART_IRQn ; vector = (uint32_t)&uart0_irq; break;
demayer 0:6bf0743ece18 244 }
demayer 0:6bf0743ece18 245
demayer 0:6bf0743ece18 246 if (enable) {
demayer 0:6bf0743ece18 247 obj->uart->IER |= 1 << irq;
demayer 0:6bf0743ece18 248 NVIC_SetVector(irq_n, vector);
demayer 0:6bf0743ece18 249 NVIC_EnableIRQ(irq_n);
demayer 0:6bf0743ece18 250 } else { // disable
demayer 0:6bf0743ece18 251 int all_disabled = 0;
demayer 0:6bf0743ece18 252 SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
demayer 0:6bf0743ece18 253
demayer 0:6bf0743ece18 254 obj->uart->IER &= ~(1 << irq);
demayer 0:6bf0743ece18 255 all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
demayer 0:6bf0743ece18 256
demayer 0:6bf0743ece18 257 if (all_disabled)
demayer 0:6bf0743ece18 258 NVIC_DisableIRQ(irq_n);
demayer 0:6bf0743ece18 259 }
demayer 0:6bf0743ece18 260 }
demayer 0:6bf0743ece18 261
demayer 0:6bf0743ece18 262 /******************************************************************************
demayer 0:6bf0743ece18 263 * READ/WRITE
demayer 0:6bf0743ece18 264 ******************************************************************************/
demayer 0:6bf0743ece18 265 int serial_getc(serial_t *obj) {
demayer 0:6bf0743ece18 266 while (!serial_readable(obj));
demayer 0:6bf0743ece18 267 return obj->uart->RBR;
demayer 0:6bf0743ece18 268 }
demayer 0:6bf0743ece18 269
demayer 0:6bf0743ece18 270 void serial_putc(serial_t *obj, int c) {
demayer 0:6bf0743ece18 271 while (!serial_writable(obj));
demayer 0:6bf0743ece18 272 obj->uart->THR = c;
demayer 0:6bf0743ece18 273 }
demayer 0:6bf0743ece18 274
demayer 0:6bf0743ece18 275 int serial_readable(serial_t *obj) {
demayer 0:6bf0743ece18 276 return obj->uart->LSR & 0x01;
demayer 0:6bf0743ece18 277 }
demayer 0:6bf0743ece18 278
demayer 0:6bf0743ece18 279 int serial_writable(serial_t *obj) {
demayer 0:6bf0743ece18 280 return obj->uart->LSR & 0x20;
demayer 0:6bf0743ece18 281 }
demayer 0:6bf0743ece18 282
demayer 0:6bf0743ece18 283 void serial_clear(serial_t *obj) {
demayer 0:6bf0743ece18 284 obj->uart->FCR = 1 << 1 // rx FIFO reset
demayer 0:6bf0743ece18 285 | 1 << 2 // tx FIFO reset
demayer 0:6bf0743ece18 286 | 0 << 6; // interrupt depth
demayer 0:6bf0743ece18 287 }
demayer 0:6bf0743ece18 288
demayer 0:6bf0743ece18 289 void serial_pinout_tx(PinName tx) {
demayer 0:6bf0743ece18 290 pinmap_pinout(tx, PinMap_UART_TX);
demayer 0:6bf0743ece18 291 }
demayer 0:6bf0743ece18 292
demayer 0:6bf0743ece18 293 void serial_break_set(serial_t *obj) {
demayer 0:6bf0743ece18 294 obj->uart->LCR |= (1 << 6);
demayer 0:6bf0743ece18 295 }
demayer 0:6bf0743ece18 296
demayer 0:6bf0743ece18 297 void serial_break_clear(serial_t *obj) {
demayer 0:6bf0743ece18 298 obj->uart->LCR &= ~(1 << 6);
demayer 0:6bf0743ece18 299 }
demayer 0:6bf0743ece18 300