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