tmk_core/tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/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 "PeripheralPins.h" // For the Peripheral to Pin Definitions found in the individual Target's Platform
  25
  26 /******************************************************************************
  27  * INITIALIZATION
  28  ******************************************************************************/
  29 #define UART_NUM    1
  30
  31 static uint32_t serial_irq_ids[UART_NUM] = {0};
  32 static uart_irq_handler irq_handler;
  33
  34 int stdio_uart_inited = 0;
  35 serial_t stdio_uart;
  36
  37 void serial_init(serial_t *obj, PinName tx, PinName rx) {
  38     int is_stdio_uart = 0;
  39
  40     // determine the UART to use
  41     UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
  42     UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
  43     UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
  44     MBED_ASSERT((int)uart != NC);
  45
  46     obj->uart = (LPC_USART_Type *)uart;
  47     LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
  48
  49     // [TODO] Consider more elegant approach
  50     // disconnect USBTX/RX mapping mux, for case when switching ports
  51 #ifdef USBTX
  52     pin_function(USBTX, 0);
  53     pin_function(USBRX, 0);
  54 #endif
  55
  56     // enable fifos and default rx trigger level
  57     obj->uart->FCR = 1 << 0  // FIFO Enable - 0 = Disables, 1 = Enabled
  58                    | 0 << 1  // Rx Fifo Reset
  59                    | 0 << 2  // Tx Fifo Reset
  60                    | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
  61
  62     // disable irqs
  63     obj->uart->IER = 0 << 0  // Rx Data available irq enable
  64                    | 0 << 1  // Tx Fifo empty irq enable
  65                    | 0 << 2; // Rx Line Status irq enable
  66
  67     // set default baud rate and format
  68     serial_baud  (obj, 9600);
  69     serial_format(obj, 8, ParityNone, 1);
  70
  71     // pinout the chosen uart
  72     pinmap_pinout(tx, PinMap_UART_TX);
  73     pinmap_pinout(rx, PinMap_UART_RX);
  74
  75     // set rx/tx pins in PullUp mode
  76     if (tx != NC) {
  77         pin_mode(tx, PullUp);
  78     }
  79     if (rx != NC) {
  80         pin_mode(rx, PullUp);
  81     }
  82
  83     switch (uart) {
  84         case UART_0: obj->index = 0; break;
  85     }
  86
  87     is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
  88
  89     if (is_stdio_uart) {
  90         stdio_uart_inited = 1;
  91         memcpy(&stdio_uart, obj, sizeof(serial_t));
  92     }
  93 }
  94
  95 void serial_free(serial_t *obj) {
  96     serial_irq_ids[obj->index] = 0;
  97 }
  98
  99 // serial_baud
 100 // set the baud rate, taking in to account the current SystemFrequency
 101 void serial_baud(serial_t *obj, int baudrate) {
 102     LPC_SYSCON->UARTCLKDIV = 0x1;
 103     uint32_t PCLK = SystemCoreClock;
 104     // First we check to see if the basic divide with no DivAddVal/MulVal
 105     // ratio gives us an integer result. If it does, we set DivAddVal = 0,
 106     // MulVal = 1. Otherwise, we search the valid ratio value range to find
 107     // the closest match. This could be more elegant, using search methods
 108     // and/or lookup tables, but the brute force method is not that much
 109     // slower, and is more maintainable.
 110     uint16_t DL = PCLK / (16 * baudrate);
 111
 112     uint8_t DivAddVal = 0;
 113     uint8_t MulVal = 1;
 114     int hit = 0;
 115     uint16_t dlv;
 116     uint8_t mv, dav;
 117     if ((PCLK % (16 * baudrate)) != 0) {     // Checking for zero remainder
 118         int err_best = baudrate, b;
 119         for (mv = 1; mv < 16 && !hit; mv++)
 120         {
 121             for (dav = 0; dav < mv; dav++)
 122             {
 123                 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
 124                 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
 125                 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
 126                 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
 127                 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
 128
 129                 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
 130                     dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
 131                 else // 2 bits headroom, use more precision
 132                     dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
 133
 134                 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
 135                 if (dlv == 0)
 136                     dlv = 1;
 137
 138                 // datasheet says if dav > 0 then DL must be >= 2
 139                 if ((dav > 0) && (dlv < 2))
 140                     dlv = 2;
 141
 142                 // integer rearrangement of the baudrate equation (with rounding)
 143                 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
 144
 145                 // check to see how we went
 146                 b = abs(b - baudrate);
 147                 if (b < err_best)
 148                 {
 149                     err_best  = b;
 150
 151                     DL        = dlv;
 152                     MulVal    = mv;
 153                     DivAddVal = dav;
 154
 155                     if (b == baudrate)
 156                     {
 157                         hit = 1;
 158                         break;
 159                     }
 160                 }
 161             }
 162         }
 163     }
 164
 165     // set LCR[DLAB] to enable writing to divider registers
 166     obj->uart->LCR |= (1 << 7);
 167
 168     // set divider values
 169     obj->uart->DLM = (DL >> 8) & 0xFF;
 170     obj->uart->DLL = (DL >> 0) & 0xFF;
 171     obj->uart->FDR = (uint32_t) DivAddVal << 0
 172                    | (uint32_t) MulVal    << 4;
 173
 174     // clear LCR[DLAB]
 175     obj->uart->LCR &= ~(1 << 7);
 176 }
 177
 178 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
 179     MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
 180     MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
 181     MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
 182            (parity == ParityForced1) || (parity == ParityForced0));
 183
 184     stop_bits -= 1;
 185     data_bits -= 5;
 186
 187     int parity_enable = 0, parity_select = 0;
 188     switch (parity) {
 189         case ParityNone: parity_enable = 0; parity_select = 0; break;
 190         case ParityOdd : parity_enable = 1; parity_select = 0; break;
 191         case ParityEven: parity_enable = 1; parity_select = 1; break;
 192         case ParityForced1: parity_enable = 1; parity_select = 2; break;
 193         case ParityForced0: parity_enable = 1; parity_select = 3; break;
 194         default:
 195             break;
 196     }
 197
 198     obj->uart->LCR = data_bits            << 0
 199                    | stop_bits            << 2
 200                    | parity_enable        << 3
 201                    | parity_select        << 4;
 202 }
 203
 204 /******************************************************************************
 205  * INTERRUPTS HANDLING
 206  ******************************************************************************/
 207 static inline void uart_irq(uint32_t iir, uint32_t index) {
 208     // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
 209     SerialIrq irq_type;
 210     switch (iir) {
 211         case 1: irq_type = TxIrq; break;
 212         case 2: irq_type = RxIrq; break;
 213         default: return;
 214     }
 215
 216     if (serial_irq_ids[index] != 0)
 217         irq_handler(serial_irq_ids[index], irq_type);
 218 }
 219
 220 void uart0_irq() {uart_irq((LPC_USART->IIR >> 1) & 0x7, 0);}
 221
 222 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
 223     irq_handler = handler;
 224     serial_irq_ids[obj->index] = id;
 225 }
 226
 227 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
 228     IRQn_Type irq_n = (IRQn_Type)0;
 229     uint32_t vector = 0;
 230     switch ((int)obj->uart) {
 231         case UART_0: irq_n=UART_IRQn ; vector = (uint32_t)&uart0_irq; break;
 232     }
 233
 234     if (enable) {
 235         obj->uart->IER |= 1 << irq;
 236         NVIC_SetVector(irq_n, vector);
 237         NVIC_EnableIRQ(irq_n);
 238     } else { // disable
 239         int all_disabled = 0;
 240         SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
 241
 242         obj->uart->IER &= ~(1 << irq);
 243         all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
 244
 245         if (all_disabled)
 246             NVIC_DisableIRQ(irq_n);
 247     }
 248 }
 249
 250 /******************************************************************************
 251  * READ/WRITE
 252  ******************************************************************************/
 253 int serial_getc(serial_t *obj) {
 254     while (!serial_readable(obj));
 255     return obj->uart->RBR;
 256 }
 257
 258 void serial_putc(serial_t *obj, int c) {
 259     while (!serial_writable(obj));
 260     obj->uart->THR = c;
 261 }
 262
 263 int serial_readable(serial_t *obj) {
 264     return obj->uart->LSR & 0x01;
 265 }
 266
 267 int serial_writable(serial_t *obj) {
 268     return obj->uart->LSR & 0x20;
 269 }
 270
 271 void serial_clear(serial_t *obj) {
 272     obj->uart->FCR = 1 << 1  // rx FIFO reset
 273                    | 1 << 2  // tx FIFO reset
 274                    | 0 << 6; // interrupt depth
 275 }
 276
 277 void serial_pinout_tx(PinName tx) {
 278     pinmap_pinout(tx, PinMap_UART_TX);
 279 }
 280
 281 void serial_break_set(serial_t *obj) {
 282     obj->uart->LCR |= (1 << 6);
 283 }
 284
 285 void serial_break_clear(serial_t *obj) {
 286     obj->uart->LCR &= ~(1 << 6);
 287 }
 288