tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/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     {P2_8 , UART_0, 0x02},
  33     {P3_5 , UART_0, 0x02},
  34     {P3_0 , UART_0, 0x03},
  35     {P1_7 , UART_0, 0x01},
  36     {NC   , NC    , 0x00}
  37 };
  38
  39 static const PinMap PinMap_UART_RX[] = {
  40     {P2_7 , UART_0, 0x02},
  41     {P3_4 , UART_0, 0x02},
  42     {P3_1 , UART_0, 0x03},
  43     {P1_6 , UART_0, 0x01},
  44     {NC   , NC    , 0x00}
  45 };
  46
  47 static uint32_t serial_irq_ids[UART_NUM] = {0};
  48 static uart_irq_handler irq_handler;
  49
  50 int stdio_uart_inited = 0;
  51 serial_t stdio_uart;
  52
  53 void serial_init(serial_t *obj, PinName tx, PinName rx) {
  54     int is_stdio_uart = 0;
  55
  56     // determine the UART to use
  57     UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
  58     UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
  59     UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
  60     MBED_ASSERT((int)uart != NC);
  61
  62     obj->uart = (LPC_UART_TypeDef *)uart;
  63     LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
  64
  65     // enable fifos and default rx trigger level
  66     obj->uart->FCR = 1 << 0  // FIFO Enable - 0 = Disables, 1 = Enabled
  67                    | 0 << 1  // Rx Fifo Reset
  68                    | 0 << 2  // Tx Fifo Reset
  69                    | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
  70
  71     // disable irqs
  72     obj->uart->IER = 0 << 0  // Rx Data available irq enable
  73                    | 0 << 1  // Tx Fifo empty irq enable
  74                    | 0 << 2; // Rx Line Status irq enable
  75
  76     // set default baud rate and format
  77     serial_baud  (obj, 9600);
  78     serial_format(obj, 8, ParityNone, 1);
  79
  80     // pinout the chosen uart
  81     pinmap_pinout(tx, PinMap_UART_TX);
  82     pinmap_pinout(rx, PinMap_UART_RX);
  83
  84     // set rx/tx pins in PullUp mode
  85     if (tx != NC) {
  86         pin_mode(tx, PullUp);
  87     }
  88     if (rx != NC) {
  89         pin_mode(rx, PullUp);
  90     }
  91
  92     switch (uart) {
  93         case UART_0: obj->index = 0; break;
  94     }
  95
  96     is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
  97
  98     if (is_stdio_uart) {
  99         stdio_uart_inited = 1;
 100         memcpy(&stdio_uart, obj, sizeof(serial_t));
 101     }
 102 }
 103
 104 void serial_free(serial_t *obj) {
 105     serial_irq_ids[obj->index] = 0;
 106 }
 107
 108 // serial_baud
 109 // set the baud rate, taking in to account the current SystemFrequency
 110 void serial_baud(serial_t *obj, int baudrate) {
 111     LPC_SYSCON->UARTCLKDIV = 0x1;
 112     uint32_t PCLK = SystemCoreClock;
 113     // First we check to see if the basic divide with no DivAddVal/MulVal
 114     // ratio gives us an integer result. If it does, we set DivAddVal = 0,
 115     // MulVal = 1. Otherwise, we search the valid ratio value range to find
 116     // the closest match. This could be more elegant, using search methods
 117     // and/or lookup tables, but the brute force method is not that much
 118     // slower, and is more maintainable.
 119     uint16_t DL = PCLK / (16 * baudrate);
 120
 121     uint8_t DivAddVal = 0;
 122     uint8_t MulVal = 1;
 123     int hit = 0;
 124     uint16_t dlv;
 125     uint8_t mv, dav;
 126     if ((PCLK % (16 * baudrate)) != 0) {     // Checking for zero remainder
 127         int err_best = baudrate, b;
 128         for (mv = 1; mv < 16 && !hit; mv++)
 129         {
 130             for (dav = 0; dav < mv; dav++)
 131             {
 132                 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
 133                 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
 134                 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
 135                 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
 136                 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
 137
 138                 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
 139                     dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
 140                 else // 2 bits headroom, use more precision
 141                     dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
 142
 143                 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
 144                 if (dlv == 0)
 145                     dlv = 1;
 146
 147                 // datasheet says if dav > 0 then DL must be >= 2
 148                 if ((dav > 0) && (dlv < 2))
 149                     dlv = 2;
 150
 151                 // integer rearrangement of the baudrate equation (with rounding)
 152                 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
 153
 154                 // check to see how we went
 155                 b = abs(b - baudrate);
 156                 if (b < err_best)
 157                 {
 158                     err_best  = b;
 159
 160                     DL        = dlv;
 161                     MulVal    = mv;
 162                     DivAddVal = dav;
 163
 164                     if (b == baudrate)
 165                     {
 166                         hit = 1;
 167                         break;
 168                     }
 169                 }
 170             }
 171         }
 172     }
 173
 174     // set LCR[DLAB] to enable writing to divider registers
 175     obj->uart->LCR |= (1 << 7);
 176
 177     // set divider values
 178     obj->uart->DLM = (DL >> 8) & 0xFF;
 179     obj->uart->DLL = (DL >> 0) & 0xFF;
 180     obj->uart->FDR = (uint32_t) DivAddVal << 0
 181                    | (uint32_t) MulVal    << 4;
 182
 183     // clear LCR[DLAB]
 184     obj->uart->LCR &= ~(1 << 7);
 185 }
 186
 187 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
 188     MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
 189     MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
 190     MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
 191            (parity == ParityForced1) || (parity == ParityForced0));
 192
 193     stop_bits -= 1;
 194     data_bits -= 5;
 195
 196     int parity_enable, parity_select;
 197     switch (parity) {
 198         case ParityNone: parity_enable = 0; parity_select = 0; break;
 199         case ParityOdd : parity_enable = 1; parity_select = 0; break;
 200         case ParityEven: parity_enable = 1; parity_select = 1; break;
 201         case ParityForced1: parity_enable = 1; parity_select = 2; break;
 202         case ParityForced0: parity_enable = 1; parity_select = 3; break;
 203         default:
 204             break;
 205     }
 206
 207     obj->uart->LCR = data_bits            << 0
 208                    | stop_bits            << 2
 209                    | parity_enable        << 3
 210                    | parity_select        << 4;
 211 }
 212
 213 /******************************************************************************
 214  * INTERRUPTS HANDLING
 215  ******************************************************************************/
 216 static inline void uart_irq(uint32_t iir, uint32_t index) {
 217     // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
 218     SerialIrq irq_type;
 219     switch (iir) {
 220         case 1: irq_type = TxIrq; break;
 221         case 2: irq_type = RxIrq; break;
 222         default: return;
 223     }
 224
 225     if (serial_irq_ids[index] != 0)
 226         irq_handler(serial_irq_ids[index], irq_type);
 227 }
 228
 229 void uart0_irq() {uart_irq((LPC_UART->IIR >> 1) & 0x7, 0);}
 230
 231 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
 232     irq_handler = handler;
 233     serial_irq_ids[obj->index] = id;
 234 }
 235
 236 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
 237     IRQn_Type irq_n = (IRQn_Type)0;
 238     uint32_t vector = 0;
 239     switch ((int)obj->uart) {
 240         case UART_0:
 241             irq_n=UART_IRQn;
 242             vector = (uint32_t)&uart0_irq;
 243             break;
 244         default:
 245             return;
 246     }
 247
 248     if (enable) {
 249         obj->uart->IER |= 1 << irq;
 250         NVIC_SetVector(irq_n, vector);
 251         NVIC_EnableIRQ(irq_n);
 252     } else { // disable
 253         int all_disabled = 0;
 254         SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
 255
 256         obj->uart->IER &= ~(1 << irq);
 257         all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
 258
 259         if (all_disabled)
 260             NVIC_DisableIRQ(irq_n);
 261     }
 262 }
 263
 264 /******************************************************************************
 265  * READ/WRITE
 266  ******************************************************************************/
 267 int serial_getc(serial_t *obj) {
 268     while (!serial_readable(obj));
 269     return obj->uart->RBR;
 270 }
 271
 272 void serial_putc(serial_t *obj, int c) {
 273     while (!serial_writable(obj));
 274     obj->uart->THR = c;
 275 }
 276
 277 int serial_readable(serial_t *obj) {
 278     return obj->uart->LSR & 0x01;
 279 }
 280
 281 int serial_writable(serial_t *obj) {
 282     return obj->uart->LSR & 0x20;
 283 }
 284
 285 void serial_clear(serial_t *obj) {
 286     obj->uart->FCR = 1 << 1  // rx FIFO reset
 287                    | 1 << 2  // tx FIFO reset
 288                    | 0 << 6; // interrupt depth
 289 }
 290
 291 void serial_pinout_tx(PinName tx) {
 292     pinmap_pinout(tx, PinMap_UART_TX);
 293 }
 294
 295 void serial_break_clear(serial_t *obj) {
 296     obj->uart->LCR &= ~(1 << 6);
 297 }
 298
 299 void serial_break_set(serial_t *obj) {
 300     obj->uart->LCR |= 1 << 6;
 301 }