Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_NXP/TARGET_LPC11UXX/serial_api.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2013 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 // math.h required for floating point operations for baud rate calculation
elessair 0:f269e3021894 17 #include <math.h>
elessair 0:f269e3021894 18 #include <string.h>
elessair 0:f269e3021894 19 #include <stdlib.h>
elessair 0:f269e3021894 20
elessair 0:f269e3021894 21 #include "serial_api.h"
elessair 0:f269e3021894 22 #include "cmsis.h"
elessair 0:f269e3021894 23 #include "pinmap.h"
elessair 0:f269e3021894 24 #include "PeripheralPins.h" // For the Peripheral to Pin Definitions found in the individual Target's Platform
elessair 0:f269e3021894 25
elessair 0:f269e3021894 26 /******************************************************************************
elessair 0:f269e3021894 27 * INITIALIZATION
elessair 0:f269e3021894 28 ******************************************************************************/
elessair 0:f269e3021894 29 #define UART_NUM 1
elessair 0:f269e3021894 30
elessair 0:f269e3021894 31 static uint32_t serial_irq_ids[UART_NUM] = {0};
elessair 0:f269e3021894 32 static uart_irq_handler irq_handler;
elessair 0:f269e3021894 33
elessair 0:f269e3021894 34 int stdio_uart_inited = 0;
elessair 0:f269e3021894 35 serial_t stdio_uart;
elessair 0:f269e3021894 36
elessair 0:f269e3021894 37 void serial_init(serial_t *obj, PinName tx, PinName rx) {
elessair 0:f269e3021894 38 int is_stdio_uart = 0;
elessair 0:f269e3021894 39
elessair 0:f269e3021894 40 // determine the UART to use
elessair 0:f269e3021894 41 UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
elessair 0:f269e3021894 42 UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
elessair 0:f269e3021894 43 UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
elessair 0:f269e3021894 44 MBED_ASSERT((int)uart != NC);
elessair 0:f269e3021894 45
elessair 0:f269e3021894 46 obj->uart = (LPC_USART_Type *)uart;
elessair 0:f269e3021894 47 LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
elessair 0:f269e3021894 48
elessair 0:f269e3021894 49 // [TODO] Consider more elegant approach
elessair 0:f269e3021894 50 // disconnect USBTX/RX mapping mux, for case when switching ports
elessair 0:f269e3021894 51 #ifdef USBTX
elessair 0:f269e3021894 52 pin_function(USBTX, 0);
elessair 0:f269e3021894 53 pin_function(USBRX, 0);
elessair 0:f269e3021894 54 #endif
elessair 0:f269e3021894 55
elessair 0:f269e3021894 56 // enable fifos and default rx trigger level
elessair 0:f269e3021894 57 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
elessair 0:f269e3021894 58 | 0 << 1 // Rx Fifo Reset
elessair 0:f269e3021894 59 | 0 << 2 // Tx Fifo Reset
elessair 0:f269e3021894 60 | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
elessair 0:f269e3021894 61
elessair 0:f269e3021894 62 // disable irqs
elessair 0:f269e3021894 63 obj->uart->IER = 0 << 0 // Rx Data available irq enable
elessair 0:f269e3021894 64 | 0 << 1 // Tx Fifo empty irq enable
elessair 0:f269e3021894 65 | 0 << 2; // Rx Line Status irq enable
elessair 0:f269e3021894 66
elessair 0:f269e3021894 67 // set default baud rate and format
elessair 0:f269e3021894 68 serial_baud (obj, 9600);
elessair 0:f269e3021894 69 serial_format(obj, 8, ParityNone, 1);
elessair 0:f269e3021894 70
elessair 0:f269e3021894 71 // pinout the chosen uart
elessair 0:f269e3021894 72 pinmap_pinout(tx, PinMap_UART_TX);
elessair 0:f269e3021894 73 pinmap_pinout(rx, PinMap_UART_RX);
elessair 0:f269e3021894 74
elessair 0:f269e3021894 75 // set rx/tx pins in PullUp mode
elessair 0:f269e3021894 76 if (tx != NC) {
elessair 0:f269e3021894 77 pin_mode(tx, PullUp);
elessair 0:f269e3021894 78 }
elessair 0:f269e3021894 79 if (rx != NC) {
elessair 0:f269e3021894 80 pin_mode(rx, PullUp);
elessair 0:f269e3021894 81 }
elessair 0:f269e3021894 82
elessair 0:f269e3021894 83 switch (uart) {
elessair 0:f269e3021894 84 case UART_0: obj->index = 0; break;
elessair 0:f269e3021894 85 }
elessair 0:f269e3021894 86
elessair 0:f269e3021894 87 is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
elessair 0:f269e3021894 88
elessair 0:f269e3021894 89 if (is_stdio_uart) {
elessair 0:f269e3021894 90 stdio_uart_inited = 1;
elessair 0:f269e3021894 91 memcpy(&stdio_uart, obj, sizeof(serial_t));
elessair 0:f269e3021894 92 }
elessair 0:f269e3021894 93 }
elessair 0:f269e3021894 94
elessair 0:f269e3021894 95 void serial_free(serial_t *obj) {
elessair 0:f269e3021894 96 serial_irq_ids[obj->index] = 0;
elessair 0:f269e3021894 97 }
elessair 0:f269e3021894 98
elessair 0:f269e3021894 99 // serial_baud
elessair 0:f269e3021894 100 // set the baud rate, taking in to account the current SystemFrequency
elessair 0:f269e3021894 101 void serial_baud(serial_t *obj, int baudrate) {
elessair 0:f269e3021894 102 LPC_SYSCON->UARTCLKDIV = 0x1;
elessair 0:f269e3021894 103 uint32_t PCLK = SystemCoreClock;
elessair 0:f269e3021894 104 // First we check to see if the basic divide with no DivAddVal/MulVal
elessair 0:f269e3021894 105 // ratio gives us an integer result. If it does, we set DivAddVal = 0,
elessair 0:f269e3021894 106 // MulVal = 1. Otherwise, we search the valid ratio value range to find
elessair 0:f269e3021894 107 // the closest match. This could be more elegant, using search methods
elessair 0:f269e3021894 108 // and/or lookup tables, but the brute force method is not that much
elessair 0:f269e3021894 109 // slower, and is more maintainable.
elessair 0:f269e3021894 110 uint16_t DL = PCLK / (16 * baudrate);
elessair 0:f269e3021894 111
elessair 0:f269e3021894 112 uint8_t DivAddVal = 0;
elessair 0:f269e3021894 113 uint8_t MulVal = 1;
elessair 0:f269e3021894 114 int hit = 0;
elessair 0:f269e3021894 115 uint16_t dlv;
elessair 0:f269e3021894 116 uint8_t mv, dav;
elessair 0:f269e3021894 117 if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
elessair 0:f269e3021894 118 int err_best = baudrate, b;
elessair 0:f269e3021894 119 for (mv = 1; mv < 16 && !hit; mv++)
elessair 0:f269e3021894 120 {
elessair 0:f269e3021894 121 for (dav = 0; dav < mv; dav++)
elessair 0:f269e3021894 122 {
elessair 0:f269e3021894 123 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
elessair 0:f269e3021894 124 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
elessair 0:f269e3021894 125 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
elessair 0:f269e3021894 126 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
elessair 0:f269e3021894 127 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
elessair 0:f269e3021894 128
elessair 0:f269e3021894 129 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
elessair 0:f269e3021894 130 dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
elessair 0:f269e3021894 131 else // 2 bits headroom, use more precision
elessair 0:f269e3021894 132 dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
elessair 0:f269e3021894 133
elessair 0:f269e3021894 134 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
elessair 0:f269e3021894 135 if (dlv == 0)
elessair 0:f269e3021894 136 dlv = 1;
elessair 0:f269e3021894 137
elessair 0:f269e3021894 138 // datasheet says if dav > 0 then DL must be >= 2
elessair 0:f269e3021894 139 if ((dav > 0) && (dlv < 2))
elessair 0:f269e3021894 140 dlv = 2;
elessair 0:f269e3021894 141
elessair 0:f269e3021894 142 // integer rearrangement of the baudrate equation (with rounding)
elessair 0:f269e3021894 143 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
elessair 0:f269e3021894 144
elessair 0:f269e3021894 145 // check to see how we went
elessair 0:f269e3021894 146 b = abs(b - baudrate);
elessair 0:f269e3021894 147 if (b < err_best)
elessair 0:f269e3021894 148 {
elessair 0:f269e3021894 149 err_best = b;
elessair 0:f269e3021894 150
elessair 0:f269e3021894 151 DL = dlv;
elessair 0:f269e3021894 152 MulVal = mv;
elessair 0:f269e3021894 153 DivAddVal = dav;
elessair 0:f269e3021894 154
elessair 0:f269e3021894 155 if (b == baudrate)
elessair 0:f269e3021894 156 {
elessair 0:f269e3021894 157 hit = 1;
elessair 0:f269e3021894 158 break;
elessair 0:f269e3021894 159 }
elessair 0:f269e3021894 160 }
elessair 0:f269e3021894 161 }
elessair 0:f269e3021894 162 }
elessair 0:f269e3021894 163 }
elessair 0:f269e3021894 164
elessair 0:f269e3021894 165 // set LCR[DLAB] to enable writing to divider registers
elessair 0:f269e3021894 166 obj->uart->LCR |= (1 << 7);
elessair 0:f269e3021894 167
elessair 0:f269e3021894 168 // set divider values
elessair 0:f269e3021894 169 obj->uart->DLM = (DL >> 8) & 0xFF;
elessair 0:f269e3021894 170 obj->uart->DLL = (DL >> 0) & 0xFF;
elessair 0:f269e3021894 171 obj->uart->FDR = (uint32_t) DivAddVal << 0
elessair 0:f269e3021894 172 | (uint32_t) MulVal << 4;
elessair 0:f269e3021894 173
elessair 0:f269e3021894 174 // clear LCR[DLAB]
elessair 0:f269e3021894 175 obj->uart->LCR &= ~(1 << 7);
elessair 0:f269e3021894 176 }
elessair 0:f269e3021894 177
elessair 0:f269e3021894 178 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
elessair 0:f269e3021894 179 MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
elessair 0:f269e3021894 180 MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
elessair 0:f269e3021894 181 MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
elessair 0:f269e3021894 182 (parity == ParityForced1) || (parity == ParityForced0));
elessair 0:f269e3021894 183
elessair 0:f269e3021894 184 stop_bits -= 1;
elessair 0:f269e3021894 185 data_bits -= 5;
elessair 0:f269e3021894 186
elessair 0:f269e3021894 187 int parity_enable = 0, parity_select = 0;
elessair 0:f269e3021894 188 switch (parity) {
elessair 0:f269e3021894 189 case ParityNone: parity_enable = 0; parity_select = 0; break;
elessair 0:f269e3021894 190 case ParityOdd : parity_enable = 1; parity_select = 0; break;
elessair 0:f269e3021894 191 case ParityEven: parity_enable = 1; parity_select = 1; break;
elessair 0:f269e3021894 192 case ParityForced1: parity_enable = 1; parity_select = 2; break;
elessair 0:f269e3021894 193 case ParityForced0: parity_enable = 1; parity_select = 3; break;
elessair 0:f269e3021894 194 default:
elessair 0:f269e3021894 195 break;
elessair 0:f269e3021894 196 }
elessair 0:f269e3021894 197
elessair 0:f269e3021894 198 obj->uart->LCR = data_bits << 0
elessair 0:f269e3021894 199 | stop_bits << 2
elessair 0:f269e3021894 200 | parity_enable << 3
elessair 0:f269e3021894 201 | parity_select << 4;
elessair 0:f269e3021894 202 }
elessair 0:f269e3021894 203
elessair 0:f269e3021894 204 /******************************************************************************
elessair 0:f269e3021894 205 * INTERRUPTS HANDLING
elessair 0:f269e3021894 206 ******************************************************************************/
elessair 0:f269e3021894 207 static inline void uart_irq(uint32_t iir, uint32_t index) {
elessair 0:f269e3021894 208 // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
elessair 0:f269e3021894 209 SerialIrq irq_type;
elessair 0:f269e3021894 210 switch (iir) {
elessair 0:f269e3021894 211 case 1: irq_type = TxIrq; break;
elessair 0:f269e3021894 212 case 2: irq_type = RxIrq; break;
elessair 0:f269e3021894 213 default: return;
elessair 0:f269e3021894 214 }
elessair 0:f269e3021894 215
elessair 0:f269e3021894 216 if (serial_irq_ids[index] != 0)
elessair 0:f269e3021894 217 irq_handler(serial_irq_ids[index], irq_type);
elessair 0:f269e3021894 218 }
elessair 0:f269e3021894 219
elessair 0:f269e3021894 220 void uart0_irq() {uart_irq((LPC_USART->IIR >> 1) & 0x7, 0);}
elessair 0:f269e3021894 221
elessair 0:f269e3021894 222 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
elessair 0:f269e3021894 223 irq_handler = handler;
elessair 0:f269e3021894 224 serial_irq_ids[obj->index] = id;
elessair 0:f269e3021894 225 }
elessair 0:f269e3021894 226
elessair 0:f269e3021894 227 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
elessair 0:f269e3021894 228 IRQn_Type irq_n = (IRQn_Type)0;
elessair 0:f269e3021894 229 uint32_t vector = 0;
elessair 0:f269e3021894 230 switch ((int)obj->uart) {
elessair 0:f269e3021894 231 case UART_0: irq_n=UART_IRQn ; vector = (uint32_t)&uart0_irq; break;
elessair 0:f269e3021894 232 }
elessair 0:f269e3021894 233
elessair 0:f269e3021894 234 if (enable) {
elessair 0:f269e3021894 235 obj->uart->IER |= 1 << irq;
elessair 0:f269e3021894 236 NVIC_SetVector(irq_n, vector);
elessair 0:f269e3021894 237 NVIC_EnableIRQ(irq_n);
elessair 0:f269e3021894 238 } else { // disable
elessair 0:f269e3021894 239 int all_disabled = 0;
elessair 0:f269e3021894 240 SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
elessair 0:f269e3021894 241
elessair 0:f269e3021894 242 obj->uart->IER &= ~(1 << irq);
elessair 0:f269e3021894 243 all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
elessair 0:f269e3021894 244
elessair 0:f269e3021894 245 if (all_disabled)
elessair 0:f269e3021894 246 NVIC_DisableIRQ(irq_n);
elessair 0:f269e3021894 247 }
elessair 0:f269e3021894 248 }
elessair 0:f269e3021894 249
elessair 0:f269e3021894 250 /******************************************************************************
elessair 0:f269e3021894 251 * READ/WRITE
elessair 0:f269e3021894 252 ******************************************************************************/
elessair 0:f269e3021894 253 int serial_getc(serial_t *obj) {
elessair 0:f269e3021894 254 while (!serial_readable(obj));
elessair 0:f269e3021894 255 return obj->uart->RBR;
elessair 0:f269e3021894 256 }
elessair 0:f269e3021894 257
elessair 0:f269e3021894 258 void serial_putc(serial_t *obj, int c) {
elessair 0:f269e3021894 259 while (!serial_writable(obj));
elessair 0:f269e3021894 260 obj->uart->THR = c;
elessair 0:f269e3021894 261 }
elessair 0:f269e3021894 262
elessair 0:f269e3021894 263 int serial_readable(serial_t *obj) {
elessair 0:f269e3021894 264 return obj->uart->LSR & 0x01;
elessair 0:f269e3021894 265 }
elessair 0:f269e3021894 266
elessair 0:f269e3021894 267 int serial_writable(serial_t *obj) {
elessair 0:f269e3021894 268 return obj->uart->LSR & 0x20;
elessair 0:f269e3021894 269 }
elessair 0:f269e3021894 270
elessair 0:f269e3021894 271 void serial_clear(serial_t *obj) {
elessair 0:f269e3021894 272 obj->uart->FCR = 1 << 1 // rx FIFO reset
elessair 0:f269e3021894 273 | 1 << 2 // tx FIFO reset
elessair 0:f269e3021894 274 | 0 << 6; // interrupt depth
elessair 0:f269e3021894 275 }
elessair 0:f269e3021894 276
elessair 0:f269e3021894 277 void serial_pinout_tx(PinName tx) {
elessair 0:f269e3021894 278 pinmap_pinout(tx, PinMap_UART_TX);
elessair 0:f269e3021894 279 }
elessair 0:f269e3021894 280
elessair 0:f269e3021894 281 void serial_break_set(serial_t *obj) {
elessair 0:f269e3021894 282 obj->uart->LCR |= (1 << 6);
elessair 0:f269e3021894 283 }
elessair 0:f269e3021894 284
elessair 0:f269e3021894 285 void serial_break_clear(serial_t *obj) {
elessair 0:f269e3021894 286 obj->uart->LCR &= ~(1 << 6);
elessair 0:f269e3021894 287 }
elessair 0:f269e3021894 288