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targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
Child:
144:ef7eb2e8f9f7
Initial commit on mbed-dev



Replaces mbed-src (now inactive)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 0:9b334a45a8ff 1 /* mbed Microcontroller Library
bogdanm 0:9b334a45a8ff 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 0:9b334a45a8ff 3 *
bogdanm 0:9b334a45a8ff 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 0:9b334a45a8ff 5 * you may not use this file except in compliance with the License.
bogdanm 0:9b334a45a8ff 6 * You may obtain a copy of the License at
bogdanm 0:9b334a45a8ff 7 *
bogdanm 0:9b334a45a8ff 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 0:9b334a45a8ff 9 *
bogdanm 0:9b334a45a8ff 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 0:9b334a45a8ff 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 0:9b334a45a8ff 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 0:9b334a45a8ff 13 * See the License for the specific language governing permissions and
bogdanm 0:9b334a45a8ff 14 * limitations under the License.
bogdanm 0:9b334a45a8ff 15 */
bogdanm 0:9b334a45a8ff 16 // math.h required for floating point operations for baud rate calculation
bogdanm 0:9b334a45a8ff 17 #include "mbed_assert.h"
bogdanm 0:9b334a45a8ff 18 #include <math.h>
bogdanm 0:9b334a45a8ff 19 #include <string.h>
bogdanm 0:9b334a45a8ff 20 #include <stdlib.h>
bogdanm 0:9b334a45a8ff 21
bogdanm 0:9b334a45a8ff 22 #include "serial_api.h"
bogdanm 0:9b334a45a8ff 23 #include "cmsis.h"
bogdanm 0:9b334a45a8ff 24 #include "pinmap.h"
bogdanm 0:9b334a45a8ff 25
bogdanm 0:9b334a45a8ff 26 /******************************************************************************
bogdanm 0:9b334a45a8ff 27 * INITIALIZATION
bogdanm 0:9b334a45a8ff 28 ******************************************************************************/
bogdanm 0:9b334a45a8ff 29 #define UART_NUM 1
bogdanm 0:9b334a45a8ff 30
bogdanm 0:9b334a45a8ff 31 static const PinMap PinMap_UART_TX[] = {
bogdanm 0:9b334a45a8ff 32 {P0_19, UART_0, 1},
bogdanm 0:9b334a45a8ff 33 {P1_13, UART_0, 3},
bogdanm 0:9b334a45a8ff 34 {P1_27, UART_0, 2},
bogdanm 0:9b334a45a8ff 35 { NC , NC , 0}
bogdanm 0:9b334a45a8ff 36 };
bogdanm 0:9b334a45a8ff 37
bogdanm 0:9b334a45a8ff 38 static const PinMap PinMap_UART_RX[] = {
bogdanm 0:9b334a45a8ff 39 {P0_18, UART_0, 1},
bogdanm 0:9b334a45a8ff 40 {P1_14, UART_0, 3},
bogdanm 0:9b334a45a8ff 41 {P1_26, UART_0, 2},
bogdanm 0:9b334a45a8ff 42 {NC , NC , 0}
bogdanm 0:9b334a45a8ff 43 };
bogdanm 0:9b334a45a8ff 44
bogdanm 0:9b334a45a8ff 45 static uint32_t serial_irq_ids[UART_NUM] = {0};
bogdanm 0:9b334a45a8ff 46 static uart_irq_handler irq_handler;
bogdanm 0:9b334a45a8ff 47
bogdanm 0:9b334a45a8ff 48 int stdio_uart_inited = 0;
bogdanm 0:9b334a45a8ff 49 serial_t stdio_uart;
bogdanm 0:9b334a45a8ff 50
bogdanm 0:9b334a45a8ff 51 void serial_init(serial_t *obj, PinName tx, PinName rx) {
bogdanm 0:9b334a45a8ff 52 int is_stdio_uart = 0;
bogdanm 0:9b334a45a8ff 53
bogdanm 0:9b334a45a8ff 54 // determine the UART to use
bogdanm 0:9b334a45a8ff 55 UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
bogdanm 0:9b334a45a8ff 56 UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
bogdanm 0:9b334a45a8ff 57 UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
bogdanm 0:9b334a45a8ff 58 MBED_ASSERT((int)uart != NC);
bogdanm 0:9b334a45a8ff 59
bogdanm 0:9b334a45a8ff 60 obj->uart = (LPC_USART_Type *)uart;
bogdanm 0:9b334a45a8ff 61 LPC_SYSCON->SYSAHBCLKCTRL |= (1<<12);
bogdanm 0:9b334a45a8ff 62
bogdanm 0:9b334a45a8ff 63 // [TODO] Consider more elegant approach
bogdanm 0:9b334a45a8ff 64 // disconnect USBTX/RX mapping mux, for case when switching ports
bogdanm 0:9b334a45a8ff 65 //pin_function(USBTX, 0);
bogdanm 0:9b334a45a8ff 66 //pin_function(USBRX, 0);
bogdanm 0:9b334a45a8ff 67
bogdanm 0:9b334a45a8ff 68 // enable fifos and default rx trigger level
bogdanm 0:9b334a45a8ff 69 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
bogdanm 0:9b334a45a8ff 70 | 0 << 1 // Rx Fifo Reset
bogdanm 0:9b334a45a8ff 71 | 0 << 2 // Tx Fifo Reset
bogdanm 0:9b334a45a8ff 72 | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
bogdanm 0:9b334a45a8ff 73
bogdanm 0:9b334a45a8ff 74 // disable irqs
bogdanm 0:9b334a45a8ff 75 obj->uart->IER = 0 << 0 // Rx Data available irq enable
bogdanm 0:9b334a45a8ff 76 | 0 << 1 // Tx Fifo empty irq enable
bogdanm 0:9b334a45a8ff 77 | 0 << 2; // Rx Line Status irq enable
bogdanm 0:9b334a45a8ff 78
bogdanm 0:9b334a45a8ff 79 // set default baud rate and format
bogdanm 0:9b334a45a8ff 80 serial_baud (obj, 9600);
bogdanm 0:9b334a45a8ff 81 serial_format(obj, 8, ParityNone, 1);
bogdanm 0:9b334a45a8ff 82
bogdanm 0:9b334a45a8ff 83 // pinout the chosen uart
bogdanm 0:9b334a45a8ff 84 pinmap_pinout(tx, PinMap_UART_TX);
bogdanm 0:9b334a45a8ff 85 pinmap_pinout(rx, PinMap_UART_RX);
bogdanm 0:9b334a45a8ff 86
bogdanm 0:9b334a45a8ff 87 // set rx/tx pins in PullUp mode
bogdanm 0:9b334a45a8ff 88 if (tx != NC) {
bogdanm 0:9b334a45a8ff 89 pin_mode(tx, PullUp);
bogdanm 0:9b334a45a8ff 90 }
bogdanm 0:9b334a45a8ff 91 if (rx != NC) {
bogdanm 0:9b334a45a8ff 92 pin_mode(rx, PullUp);
bogdanm 0:9b334a45a8ff 93 }
bogdanm 0:9b334a45a8ff 94
bogdanm 0:9b334a45a8ff 95 switch (uart) {
bogdanm 0:9b334a45a8ff 96 case UART_0: obj->index = 0; break;
bogdanm 0:9b334a45a8ff 97 }
bogdanm 0:9b334a45a8ff 98
bogdanm 0:9b334a45a8ff 99 is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
bogdanm 0:9b334a45a8ff 100
bogdanm 0:9b334a45a8ff 101 if (is_stdio_uart) {
bogdanm 0:9b334a45a8ff 102 stdio_uart_inited = 1;
bogdanm 0:9b334a45a8ff 103 memcpy(&stdio_uart, obj, sizeof(serial_t));
bogdanm 0:9b334a45a8ff 104 }
bogdanm 0:9b334a45a8ff 105 }
bogdanm 0:9b334a45a8ff 106
bogdanm 0:9b334a45a8ff 107 void serial_free(serial_t *obj) {
bogdanm 0:9b334a45a8ff 108 serial_irq_ids[obj->index] = 0;
bogdanm 0:9b334a45a8ff 109 }
bogdanm 0:9b334a45a8ff 110
bogdanm 0:9b334a45a8ff 111 // serial_baud
bogdanm 0:9b334a45a8ff 112 // set the baud rate, taking in to account the current SystemFrequency
bogdanm 0:9b334a45a8ff 113 void serial_baud(serial_t *obj, int baudrate) {
bogdanm 0:9b334a45a8ff 114 LPC_SYSCON->UARTCLKDIV = 0x1;
bogdanm 0:9b334a45a8ff 115 uint32_t PCLK = SystemCoreClock;
bogdanm 0:9b334a45a8ff 116 // First we check to see if the basic divide with no DivAddVal/MulVal
bogdanm 0:9b334a45a8ff 117 // ratio gives us an integer result. If it does, we set DivAddVal = 0,
bogdanm 0:9b334a45a8ff 118 // MulVal = 1. Otherwise, we search the valid ratio value range to find
bogdanm 0:9b334a45a8ff 119 // the closest match. This could be more elegant, using search methods
bogdanm 0:9b334a45a8ff 120 // and/or lookup tables, but the brute force method is not that much
bogdanm 0:9b334a45a8ff 121 // slower, and is more maintainable.
bogdanm 0:9b334a45a8ff 122 uint16_t DL = PCLK / (16 * baudrate);
bogdanm 0:9b334a45a8ff 123
bogdanm 0:9b334a45a8ff 124 uint8_t DivAddVal = 0;
bogdanm 0:9b334a45a8ff 125 uint8_t MulVal = 1;
bogdanm 0:9b334a45a8ff 126 int hit = 0;
bogdanm 0:9b334a45a8ff 127 uint16_t dlv;
bogdanm 0:9b334a45a8ff 128 uint8_t mv, dav;
bogdanm 0:9b334a45a8ff 129 if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
bogdanm 0:9b334a45a8ff 130 int err_best = baudrate, b;
bogdanm 0:9b334a45a8ff 131 for (mv = 1; mv < 16 && !hit; mv++)
bogdanm 0:9b334a45a8ff 132 {
bogdanm 0:9b334a45a8ff 133 for (dav = 0; dav < mv; dav++)
bogdanm 0:9b334a45a8ff 134 {
bogdanm 0:9b334a45a8ff 135 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
bogdanm 0:9b334a45a8ff 136 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
bogdanm 0:9b334a45a8ff 137 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
bogdanm 0:9b334a45a8ff 138 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
bogdanm 0:9b334a45a8ff 139 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
bogdanm 0:9b334a45a8ff 140
bogdanm 0:9b334a45a8ff 141 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
bogdanm 0:9b334a45a8ff 142 dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
bogdanm 0:9b334a45a8ff 143 else // 2 bits headroom, use more precision
bogdanm 0:9b334a45a8ff 144 dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
bogdanm 0:9b334a45a8ff 145
bogdanm 0:9b334a45a8ff 146 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
bogdanm 0:9b334a45a8ff 147 if (dlv == 0)
bogdanm 0:9b334a45a8ff 148 dlv = 1;
bogdanm 0:9b334a45a8ff 149
bogdanm 0:9b334a45a8ff 150 // datasheet says if dav > 0 then DL must be >= 2
bogdanm 0:9b334a45a8ff 151 if ((dav > 0) && (dlv < 2))
bogdanm 0:9b334a45a8ff 152 dlv = 2;
bogdanm 0:9b334a45a8ff 153
bogdanm 0:9b334a45a8ff 154 // integer rearrangement of the baudrate equation (with rounding)
bogdanm 0:9b334a45a8ff 155 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
bogdanm 0:9b334a45a8ff 156
bogdanm 0:9b334a45a8ff 157 // check to see how we went
bogdanm 0:9b334a45a8ff 158 b = abs(b - baudrate);
bogdanm 0:9b334a45a8ff 159 if (b < err_best)
bogdanm 0:9b334a45a8ff 160 {
bogdanm 0:9b334a45a8ff 161 err_best = b;
bogdanm 0:9b334a45a8ff 162
bogdanm 0:9b334a45a8ff 163 DL = dlv;
bogdanm 0:9b334a45a8ff 164 MulVal = mv;
bogdanm 0:9b334a45a8ff 165 DivAddVal = dav;
bogdanm 0:9b334a45a8ff 166
bogdanm 0:9b334a45a8ff 167 if (b == baudrate)
bogdanm 0:9b334a45a8ff 168 {
bogdanm 0:9b334a45a8ff 169 hit = 1;
bogdanm 0:9b334a45a8ff 170 break;
bogdanm 0:9b334a45a8ff 171 }
bogdanm 0:9b334a45a8ff 172 }
bogdanm 0:9b334a45a8ff 173 }
bogdanm 0:9b334a45a8ff 174 }
bogdanm 0:9b334a45a8ff 175 }
bogdanm 0:9b334a45a8ff 176
bogdanm 0:9b334a45a8ff 177 // set LCR[DLAB] to enable writing to divider registers
bogdanm 0:9b334a45a8ff 178 obj->uart->LCR |= (1 << 7);
bogdanm 0:9b334a45a8ff 179
bogdanm 0:9b334a45a8ff 180 // set divider values
bogdanm 0:9b334a45a8ff 181 obj->uart->DLM = (DL >> 8) & 0xFF;
bogdanm 0:9b334a45a8ff 182 obj->uart->DLL = (DL >> 0) & 0xFF;
bogdanm 0:9b334a45a8ff 183 obj->uart->FDR = (uint32_t) DivAddVal << 0
bogdanm 0:9b334a45a8ff 184 | (uint32_t) MulVal << 4;
bogdanm 0:9b334a45a8ff 185
bogdanm 0:9b334a45a8ff 186 // clear LCR[DLAB]
bogdanm 0:9b334a45a8ff 187 obj->uart->LCR &= ~(1 << 7);
bogdanm 0:9b334a45a8ff 188 }
bogdanm 0:9b334a45a8ff 189
bogdanm 0:9b334a45a8ff 190 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
bogdanm 0:9b334a45a8ff 191 MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
bogdanm 0:9b334a45a8ff 192 MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
bogdanm 0:9b334a45a8ff 193 MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
bogdanm 0:9b334a45a8ff 194 (parity == ParityForced1) || (parity == ParityForced0));
bogdanm 0:9b334a45a8ff 195
bogdanm 0:9b334a45a8ff 196 stop_bits -= 1;
bogdanm 0:9b334a45a8ff 197 data_bits -= 5;
bogdanm 0:9b334a45a8ff 198
bogdanm 0:9b334a45a8ff 199 int parity_enable, parity_select;
bogdanm 0:9b334a45a8ff 200 switch (parity) {
bogdanm 0:9b334a45a8ff 201 case ParityNone: parity_enable = 0; parity_select = 0; break;
bogdanm 0:9b334a45a8ff 202 case ParityOdd : parity_enable = 1; parity_select = 0; break;
bogdanm 0:9b334a45a8ff 203 case ParityEven: parity_enable = 1; parity_select = 1; break;
bogdanm 0:9b334a45a8ff 204 case ParityForced1: parity_enable = 1; parity_select = 2; break;
bogdanm 0:9b334a45a8ff 205 case ParityForced0: parity_enable = 1; parity_select = 3; break;
bogdanm 0:9b334a45a8ff 206 default:
bogdanm 0:9b334a45a8ff 207 break;
bogdanm 0:9b334a45a8ff 208 }
bogdanm 0:9b334a45a8ff 209
bogdanm 0:9b334a45a8ff 210 obj->uart->LCR = data_bits << 0
bogdanm 0:9b334a45a8ff 211 | stop_bits << 2
bogdanm 0:9b334a45a8ff 212 | parity_enable << 3
bogdanm 0:9b334a45a8ff 213 | parity_select << 4;
bogdanm 0:9b334a45a8ff 214 }
bogdanm 0:9b334a45a8ff 215
bogdanm 0:9b334a45a8ff 216 /******************************************************************************
bogdanm 0:9b334a45a8ff 217 * INTERRUPTS HANDLING
bogdanm 0:9b334a45a8ff 218 ******************************************************************************/
bogdanm 0:9b334a45a8ff 219 static inline void uart_irq(uint32_t iir, uint32_t index) {
bogdanm 0:9b334a45a8ff 220 // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
bogdanm 0:9b334a45a8ff 221 SerialIrq irq_type;
bogdanm 0:9b334a45a8ff 222 switch (iir) {
bogdanm 0:9b334a45a8ff 223 case 1: irq_type = TxIrq; break;
bogdanm 0:9b334a45a8ff 224 case 2: irq_type = RxIrq; break;
bogdanm 0:9b334a45a8ff 225 default: return;
bogdanm 0:9b334a45a8ff 226 }
bogdanm 0:9b334a45a8ff 227
bogdanm 0:9b334a45a8ff 228 if (serial_irq_ids[index] != 0)
bogdanm 0:9b334a45a8ff 229 irq_handler(serial_irq_ids[index], irq_type);
bogdanm 0:9b334a45a8ff 230 }
bogdanm 0:9b334a45a8ff 231
bogdanm 0:9b334a45a8ff 232 void uart0_irq() {uart_irq((LPC_USART->IIR >> 1) & 0x7, 0);}
bogdanm 0:9b334a45a8ff 233
bogdanm 0:9b334a45a8ff 234 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
bogdanm 0:9b334a45a8ff 235 irq_handler = handler;
bogdanm 0:9b334a45a8ff 236 serial_irq_ids[obj->index] = id;
bogdanm 0:9b334a45a8ff 237 }
bogdanm 0:9b334a45a8ff 238
bogdanm 0:9b334a45a8ff 239 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
bogdanm 0:9b334a45a8ff 240 IRQn_Type irq_n = (IRQn_Type)0;
bogdanm 0:9b334a45a8ff 241 uint32_t vector = 0;
bogdanm 0:9b334a45a8ff 242 switch ((int)obj->uart) {
bogdanm 0:9b334a45a8ff 243 case UART_0: irq_n=USART_IRQn ; vector = (uint32_t)&uart0_irq; break;
bogdanm 0:9b334a45a8ff 244 }
bogdanm 0:9b334a45a8ff 245
bogdanm 0:9b334a45a8ff 246 if (enable) {
bogdanm 0:9b334a45a8ff 247 obj->uart->IER |= 1 << irq;
bogdanm 0:9b334a45a8ff 248 NVIC_SetVector(irq_n, vector);
bogdanm 0:9b334a45a8ff 249 NVIC_EnableIRQ(irq_n);
bogdanm 0:9b334a45a8ff 250 } else { // disable
bogdanm 0:9b334a45a8ff 251 int all_disabled = 0;
bogdanm 0:9b334a45a8ff 252 SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
bogdanm 0:9b334a45a8ff 253
bogdanm 0:9b334a45a8ff 254 obj->uart->IER &= ~(1 << irq);
bogdanm 0:9b334a45a8ff 255 all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
bogdanm 0:9b334a45a8ff 256
bogdanm 0:9b334a45a8ff 257 if (all_disabled)
bogdanm 0:9b334a45a8ff 258 NVIC_DisableIRQ(irq_n);
bogdanm 0:9b334a45a8ff 259 }
bogdanm 0:9b334a45a8ff 260 }
bogdanm 0:9b334a45a8ff 261
bogdanm 0:9b334a45a8ff 262 /******************************************************************************
bogdanm 0:9b334a45a8ff 263 * READ/WRITE
bogdanm 0:9b334a45a8ff 264 ******************************************************************************/
bogdanm 0:9b334a45a8ff 265 int serial_getc(serial_t *obj) {
bogdanm 0:9b334a45a8ff 266 while (!serial_readable(obj));
bogdanm 0:9b334a45a8ff 267 return obj->uart->RBR;
bogdanm 0:9b334a45a8ff 268 }
bogdanm 0:9b334a45a8ff 269
bogdanm 0:9b334a45a8ff 270 void serial_putc(serial_t *obj, int c) {
bogdanm 0:9b334a45a8ff 271 while (!serial_writable(obj));
bogdanm 0:9b334a45a8ff 272 obj->uart->THR = c;
bogdanm 0:9b334a45a8ff 273 }
bogdanm 0:9b334a45a8ff 274
bogdanm 0:9b334a45a8ff 275 int serial_readable(serial_t *obj) {
bogdanm 0:9b334a45a8ff 276 return obj->uart->LSR & 0x01;
bogdanm 0:9b334a45a8ff 277 }
bogdanm 0:9b334a45a8ff 278
bogdanm 0:9b334a45a8ff 279 int serial_writable(serial_t *obj) {
bogdanm 0:9b334a45a8ff 280 return obj->uart->LSR & 0x20;
bogdanm 0:9b334a45a8ff 281 }
bogdanm 0:9b334a45a8ff 282
bogdanm 0:9b334a45a8ff 283 void serial_clear(serial_t *obj) {
bogdanm 0:9b334a45a8ff 284 obj->uart->FCR = 1 << 1 // rx FIFO reset
bogdanm 0:9b334a45a8ff 285 | 1 << 2 // tx FIFO reset
bogdanm 0:9b334a45a8ff 286 | 0 << 6; // interrupt depth
bogdanm 0:9b334a45a8ff 287 }
bogdanm 0:9b334a45a8ff 288
bogdanm 0:9b334a45a8ff 289 void serial_pinout_tx(PinName tx) {
bogdanm 0:9b334a45a8ff 290 pinmap_pinout(tx, PinMap_UART_TX);
bogdanm 0:9b334a45a8ff 291 }
bogdanm 0:9b334a45a8ff 292
bogdanm 0:9b334a45a8ff 293 void serial_break_set(serial_t *obj) {
bogdanm 0:9b334a45a8ff 294 obj->uart->LCR |= (1 << 6);
bogdanm 0:9b334a45a8ff 295 }
bogdanm 0:9b334a45a8ff 296
bogdanm 0:9b334a45a8ff 297 void serial_break_clear(serial_t *obj) {
bogdanm 0:9b334a45a8ff 298 obj->uart->LCR &= ~(1 << 6);
bogdanm 0:9b334a45a8ff 299 }
bogdanm 0:9b334a45a8ff 300