tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/TARGET_LPC4088_DM/serial_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 // math.h required for floating point operations for baud rate calculation
  17 #include <math.h>
  18 #include <string.h>
  19 #include <stdlib.h>
  20
  21 #include "serial_api.h"
  22 #include "cmsis.h"
  23 #include "pinmap.h"
  24 #include "mbed_error.h"
  25
  26 /******************************************************************************
  27  * INITIALIZATION
  28  ******************************************************************************/
  29 static const PinMap PinMap_UART_TX[] = {
  30     {P0_0,  UART_3, 2},
  31     {P0_2,  UART_0, 1},
  32     {P0_25, UART_3, 3},
  33     {P4_22, UART_2, 2},
  34     {P5_4,  UART_4, 4},
  35     {NC   , NC    , 0}
  36 };
  37
  38 static const PinMap PinMap_UART_RX[] = {
  39     {P0_1 , UART_3, 2},
  40     {P0_3 , UART_0, 1},
  41     {P0_26, UART_3, 3},
  42     {P4_23, UART_2, 2},
  43     {P5_3,  UART_4, 4},
  44     {NC   , NC    , 0}
  45 };
  46
  47 #define UART_NUM    5
  48
  49 static uint32_t serial_irq_ids[UART_NUM] = {0};
  50 static uart_irq_handler irq_handler;
  51
  52 int stdio_uart_inited = 0;
  53 serial_t stdio_uart;
  54
  55 void serial_init(serial_t *obj, PinName tx, PinName rx) {
  56     int is_stdio_uart = 0;
  57
  58     // determine the UART to use
  59     UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
  60     UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
  61     UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
  62     MBED_ASSERT((int)uart != NC);
  63
  64     obj->uart = (LPC_UART_TypeDef *)uart;
  65     // enable power
  66     switch (uart) {
  67         case UART_0: LPC_SC->PCONP |= 1 <<  3; break;
  68         case UART_1: LPC_SC->PCONP |= 1 <<  4; break;
  69         case UART_2: LPC_SC->PCONP |= 1 << 24; break;
  70         case UART_3: LPC_SC->PCONP |= 1 << 25; break;
  71         case UART_4: LPC_SC->PCONP |= 1 <<  8; break;
  72     }
  73
  74     // enable fifos and default rx trigger level
  75     obj->uart->FCR = 1 << 0  // FIFO Enable - 0 = Disables, 1 = Enabled
  76                    | 0 << 1  // Rx Fifo Reset
  77                    | 0 << 2  // Tx Fifo Reset
  78                    | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
  79
  80     // disable irqs
  81     obj->uart->IER = 0 << 0  // Rx Data available irq enable
  82                    | 0 << 1  // Tx Fifo empty irq enable
  83                    | 0 << 2; // Rx Line Status irq enable
  84
  85     // set default baud rate and format
  86     serial_baud  (obj, 9600);
  87     serial_format(obj, 8, ParityNone, 1);
  88
  89     // pinout the chosen uart
  90     pinmap_pinout(tx, PinMap_UART_TX);
  91     pinmap_pinout(rx, PinMap_UART_RX);
  92
  93     // set rx/tx pins in PullUp mode
  94     if (tx != NC) {
  95         pin_mode(tx, PullUp);
  96     }
  97     if (rx != NC) {
  98         pin_mode(rx, PullUp);
  99     }
 100
 101     switch (uart) {
 102         case UART_0: obj->index = 0; break;
 103         case UART_1: obj->index = 1; break;
 104         case UART_2: obj->index = 2; break;
 105         case UART_3: obj->index = 3; break;
 106         case UART_4: obj->index = 4; break;
 107     }
 108
 109     is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
 110
 111     if (is_stdio_uart) {
 112         stdio_uart_inited = 1;
 113         memcpy(&stdio_uart, obj, sizeof(serial_t));
 114     }
 115 }
 116
 117 void serial_free(serial_t *obj) {
 118     serial_irq_ids[obj->index] = 0;
 119 }
 120
 121 // serial_baud
 122 // set the baud rate, taking in to account the current SystemFrequency
 123 void serial_baud(serial_t *obj, int baudrate) {
 124     uint32_t PCLK = PeripheralClock;
 125
 126     // First we check to see if the basic divide with no DivAddVal/MulVal
 127     // ratio gives us an integer result. If it does, we set DivAddVal = 0,
 128     // MulVal = 1. Otherwise, we search the valid ratio value range to find
 129     // the closest match. This could be more elegant, using search methods
 130     // and/or lookup tables, but the brute force method is not that much
 131     // slower, and is more maintainable.
 132     uint16_t DL = PCLK / (16 * baudrate);
 133
 134     uint8_t DivAddVal = 0;
 135     uint8_t MulVal = 1;
 136     int hit = 0;
 137     uint16_t dlv;
 138     uint8_t mv, dav;
 139     if ((PCLK % (16 * baudrate)) != 0) {     // Checking for zero remainder
 140         int err_best = baudrate, b;
 141         for (mv = 1; mv < 16 && !hit; mv++)
 142         {
 143             for (dav = 0; dav < mv; dav++)
 144             {
 145                 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
 146                 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
 147                 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
 148                 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
 149                 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
 150
 151                 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
 152                     dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
 153                 else // 2 bits headroom, use more precision
 154                     dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
 155
 156                 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
 157                 if (dlv == 0)
 158                     dlv = 1;
 159
 160                 // datasheet says if dav > 0 then DL must be >= 2
 161                 if ((dav > 0) && (dlv < 2))
 162                     dlv = 2;
 163
 164                 // integer rearrangement of the baudrate equation (with rounding)
 165                 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
 166
 167                 // check to see how we went
 168                 b = abs(b - baudrate);
 169                 if (b < err_best)
 170                 {
 171                     err_best  = b;
 172
 173                     DL        = dlv;
 174                     MulVal    = mv;
 175                     DivAddVal = dav;
 176
 177                     if (b == baudrate)
 178                     {
 179                         hit = 1;
 180                         break;
 181                     }
 182                 }
 183             }
 184         }
 185     }
 186
 187     // set LCR[DLAB] to enable writing to divider registers
 188     obj->uart->LCR |= (1 << 7);
 189
 190     // set divider values
 191     obj->uart->DLM = (DL >> 8) & 0xFF;
 192     obj->uart->DLL = (DL >> 0) & 0xFF;
 193     obj->uart->FDR = (uint32_t) DivAddVal << 0
 194                    | (uint32_t) MulVal    << 4;
 195
 196     // clear LCR[DLAB]
 197     obj->uart->LCR &= ~(1 << 7);
 198 }
 199
 200 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
 201     MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
 202     MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
 203     MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
 204            (parity == ParityForced1) || (parity == ParityForced0));
 205
 206     stop_bits -= 1;
 207     data_bits -= 5;
 208
 209     int parity_enable, parity_select;
 210     switch (parity) {
 211         case ParityNone: parity_enable = 0; parity_select = 0; break;
 212         case ParityOdd : parity_enable = 1; parity_select = 0; break;
 213         case ParityEven: parity_enable = 1; parity_select = 1; break;
 214         case ParityForced1: parity_enable = 1; parity_select = 2; break;
 215         case ParityForced0: parity_enable = 1; parity_select = 3; break;
 216         default:
 217             break;
 218     }
 219
 220     obj->uart->LCR = data_bits            << 0
 221                    | stop_bits            << 2
 222                    | parity_enable        << 3
 223                    | parity_select        << 4;
 224 }
 225
 226 /******************************************************************************
 227  * INTERRUPTS HANDLING
 228  ******************************************************************************/
 229 static inline void uart_irq(uint32_t iir, uint32_t index) {
 230     // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
 231     SerialIrq irq_type;
 232     switch (iir) {
 233         case 1: irq_type = TxIrq; break;
 234         case 2: irq_type = RxIrq; break;
 235         default: return;
 236     }
 237
 238     if (serial_irq_ids[index] != 0)
 239         irq_handler(serial_irq_ids[index], irq_type);
 240 }
 241
 242 void uart0_irq() {uart_irq((LPC_UART0->IIR >> 1) & 0x7, 0);}
 243 void uart1_irq() {uart_irq((LPC_UART1->IIR >> 1) & 0x7, 1);}
 244 void uart2_irq() {uart_irq((LPC_UART2->IIR >> 1) & 0x7, 2);}
 245 void uart3_irq() {uart_irq((LPC_UART3->IIR >> 1) & 0x7, 3);}
 246 void uart4_irq() {uart_irq((LPC_UART4->IIR >> 1) & 0x7, 4);}
 247
 248 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
 249     irq_handler = handler;
 250     serial_irq_ids[obj->index] = id;
 251 }
 252
 253 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
 254     IRQn_Type irq_n = (IRQn_Type)0;
 255     uint32_t vector = 0;
 256     switch ((int)obj->uart) {
 257         case UART_0: irq_n=UART0_IRQn; vector = (uint32_t)&uart0_irq; break;
 258         case UART_1: irq_n=UART1_IRQn; vector = (uint32_t)&uart1_irq; break;
 259         case UART_2: irq_n=UART2_IRQn; vector = (uint32_t)&uart2_irq; break;
 260         case UART_3: irq_n=UART3_IRQn; vector = (uint32_t)&uart3_irq; break;
 261         case UART_4: irq_n=UART4_IRQn; vector = (uint32_t)&uart4_irq; break;
 262     }
 263
 264     if (enable) {
 265         obj->uart->IER |= 1 << irq;
 266         NVIC_SetVector(irq_n, vector);
 267         NVIC_EnableIRQ(irq_n);
 268     } else { // disable
 269         int all_disabled = 0;
 270         SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
 271         obj->uart->IER &= ~(1 << irq);
 272         all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
 273         if (all_disabled)
 274             NVIC_DisableIRQ(irq_n);
 275     }
 276 }
 277
 278 /******************************************************************************
 279  * READ/WRITE
 280  ******************************************************************************/
 281 int serial_getc(serial_t *obj) {
 282     while (!serial_readable(obj));
 283     return obj->uart->RBR;
 284 }
 285
 286 void serial_putc(serial_t *obj, int c) {
 287     while (!serial_writable(obj));
 288     obj->uart->THR = c;
 289 }
 290
 291 int serial_readable(serial_t *obj) {
 292     return obj->uart->LSR & 0x01;
 293 }
 294
 295 int serial_writable(serial_t *obj) {
 296     return obj->uart->LSR & 0x20;
 297 }
 298
 299 void serial_clear(serial_t *obj) {
 300     obj->uart->FCR = 1 << 0  // FIFO Enable - 0 = Disables, 1 = Enabled
 301             | 1 << 1  // rx FIFO reset
 302             | 1 << 2  // tx FIFO reset
 303             | 0 << 6; // interrupt depth
 304 }
 305
 306 void serial_pinout_tx(PinName tx) {
 307     pinmap_pinout(tx, PinMap_UART_TX);
 308 }
 309
 310 void serial_break_set(serial_t *obj) {
 311     obj->uart->LCR |= (1 << 6);
 312 }
 313
 314 void serial_break_clear(serial_t *obj) {
 315     obj->uart->LCR &= ~(1 << 6);
 316 }
 317