1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2013 ARM Limited
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
16 // math.h required for floating point operations for baud rate calculation
17 #include "mbed_assert.h"
22 #include "serial_api.h"
26 /******************************************************************************
28 ******************************************************************************/
31 static const PinMap PinMap_UART_TX[] = {
43 static const PinMap PinMap_UART_RX[] = {
55 static uint32_t serial_irq_ids[UART_NUM] = {0};
56 static uart_irq_handler irq_handler;
58 int stdio_uart_inited = 0;
61 void serial_init(serial_t *obj, PinName tx, PinName rx) {
62 int is_stdio_uart = 0;
64 // determine the UART to use
65 UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
66 UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
67 UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
68 MBED_ASSERT((int)uart != NC);
70 obj->uart = (LPC_UART_TypeDef *)uart;
73 case UART_0: LPC_SC->PCONP |= 1 << 3; break;
74 case UART_1: LPC_SC->PCONP |= 1 << 4; break;
75 case UART_2: LPC_SC->PCONP |= 1 << 24; break;
76 case UART_3: LPC_SC->PCONP |= 1 << 25; break;
79 // enable fifos and default rx trigger level
80 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
81 | 0 << 1 // Rx Fifo Reset
82 | 0 << 2 // Tx Fifo Reset
83 | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
86 obj->uart->IER = 0 << 0 // Rx Data available irq enable
87 | 0 << 1 // Tx Fifo empty irq enable
88 | 0 << 2; // Rx Line Status irq enable
90 // set default baud rate and format
91 serial_baud (obj, 9600);
92 serial_format(obj, 8, ParityNone, 1);
94 // pinout the chosen uart
95 pinmap_pinout(tx, PinMap_UART_TX);
96 pinmap_pinout(rx, PinMap_UART_RX);
98 // set rx/tx pins in PullUp mode
100 pin_mode(tx, PullUp);
103 pin_mode(rx, PullUp);
107 case UART_0: obj->index = 0; break;
108 case UART_1: obj->index = 1; break;
109 case UART_2: obj->index = 2; break;
110 case UART_3: obj->index = 3; break;
113 is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
116 stdio_uart_inited = 1;
117 memcpy(&stdio_uart, obj, sizeof(serial_t));
121 void serial_free(serial_t *obj) {
122 serial_irq_ids[obj->index] = 0;
126 // set the baud rate, taking in to account the current SystemFrequency
127 void serial_baud(serial_t *obj, int baudrate) {
128 MBED_ASSERT((int)obj->uart <= UART_3);
129 // The LPC2300 and LPC1700 have a divider and a fractional divider to control the
130 // baud rate. The formula is:
132 // Baudrate = (1 / PCLK) * 16 * DL * (1 + DivAddVal / MulVal)
135 // 0 <= DivAddVal < 14
136 // DivAddVal < MulVal
139 switch ((int)obj->uart) {
140 case UART_0: LPC_SC->PCLKSEL0 &= ~(0x3 << 6); LPC_SC->PCLKSEL0 |= (0x1 << 6); break;
141 case UART_1: LPC_SC->PCLKSEL0 &= ~(0x3 << 8); LPC_SC->PCLKSEL0 |= (0x1 << 8); break;
142 case UART_2: LPC_SC->PCLKSEL1 &= ~(0x3 << 16); LPC_SC->PCLKSEL1 |= (0x1 << 16); break;
143 case UART_3: LPC_SC->PCLKSEL1 &= ~(0x3 << 18); LPC_SC->PCLKSEL1 |= (0x1 << 18); break;
147 uint32_t PCLK = SystemCoreClock;
149 // First we check to see if the basic divide with no DivAddVal/MulVal
150 // ratio gives us an integer result. If it does, we set DivAddVal = 0,
151 // MulVal = 1. Otherwise, we search the valid ratio value range to find
152 // the closest match. This could be more elegant, using search methods
153 // and/or lookup tables, but the brute force method is not that much
154 // slower, and is more maintainable.
155 uint16_t DL = PCLK / (16 * baudrate);
157 uint8_t DivAddVal = 0;
162 if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
163 int err_best = baudrate, b;
164 for (mv = 1; mv < 16 && !hit; mv++)
166 for (dav = 0; dav < mv; dav++)
168 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
169 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
170 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
171 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
172 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
174 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
175 dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
176 else // 2 bits headroom, use more precision
177 dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
179 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
183 // datasheet says if dav > 0 then DL must be >= 2
184 if ((dav > 0) && (dlv < 2))
187 // integer rearrangement of the baudrate equation (with rounding)
188 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
190 // check to see how we went
191 b = abs(b - baudrate);
210 // set LCR[DLAB] to enable writing to divider registers
211 obj->uart->LCR |= (1 << 7);
213 // set divider values
214 obj->uart->DLM = (DL >> 8) & 0xFF;
215 obj->uart->DLL = (DL >> 0) & 0xFF;
216 obj->uart->FDR = (uint32_t) DivAddVal << 0
217 | (uint32_t) MulVal << 4;
220 obj->uart->LCR &= ~(1 << 7);
223 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
224 MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
225 MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
226 MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
227 (parity == ParityForced1) || (parity == ParityForced0));
232 int parity_enable = 0, parity_select = 0;
234 case ParityNone: parity_enable = 0; parity_select = 0; break;
235 case ParityOdd : parity_enable = 1; parity_select = 0; break;
236 case ParityEven: parity_enable = 1; parity_select = 1; break;
237 case ParityForced1: parity_enable = 1; parity_select = 2; break;
238 case ParityForced0: parity_enable = 1; parity_select = 3; break;
243 obj->uart->LCR = data_bits << 0
246 | parity_select << 4;
249 /******************************************************************************
250 * INTERRUPTS HANDLING
251 ******************************************************************************/
252 static inline void uart_irq(uint32_t iir, uint32_t index) {
253 // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
256 case 1: irq_type = TxIrq; break;
257 case 2: irq_type = RxIrq; break;
261 if (serial_irq_ids[index] != 0)
262 irq_handler(serial_irq_ids[index], irq_type);
265 void uart0_irq() {uart_irq((LPC_UART0->IIR >> 1) & 0x7, 0);}
266 void uart1_irq() {uart_irq((LPC_UART1->IIR >> 1) & 0x7, 1);}
267 void uart2_irq() {uart_irq((LPC_UART2->IIR >> 1) & 0x7, 2);}
268 void uart3_irq() {uart_irq((LPC_UART3->IIR >> 1) & 0x7, 3);}
270 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
271 irq_handler = handler;
272 serial_irq_ids[obj->index] = id;
275 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
276 IRQn_Type irq_n = (IRQn_Type)0;
278 switch ((int)obj->uart) {
279 case UART_0: irq_n=UART0_IRQn; vector = (uint32_t)&uart0_irq; break;
280 case UART_1: irq_n=UART1_IRQn; vector = (uint32_t)&uart1_irq; break;
281 case UART_2: irq_n=UART2_IRQn; vector = (uint32_t)&uart2_irq; break;
282 case UART_3: irq_n=UART3_IRQn; vector = (uint32_t)&uart3_irq; break;
286 obj->uart->IER |= 1 << irq;
287 NVIC_SetVector(irq_n, vector);
288 NVIC_EnableIRQ(irq_n);
290 int all_disabled = 0;
291 SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
292 obj->uart->IER &= ~(1 << irq);
293 all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
295 NVIC_DisableIRQ(irq_n);
299 /******************************************************************************
301 ******************************************************************************/
302 int serial_getc(serial_t *obj) {
303 while (!serial_readable(obj));
304 return obj->uart->RBR;
307 void serial_putc(serial_t *obj, int c) {
308 while (!serial_writable(obj));
312 int serial_readable(serial_t *obj) {
313 return obj->uart->LSR & 0x01;
316 int serial_writable(serial_t *obj) {
317 return obj->uart->LSR & 0x20;
320 void serial_clear(serial_t *obj) {
321 obj->uart->FCR = 1 << 1 // rx FIFO reset
322 | 1 << 2 // tx FIFO reset
323 | 0 << 6; // interrupt depth
326 void serial_pinout_tx(PinName tx) {
327 pinmap_pinout(tx, PinMap_UART_TX);
330 void serial_break_set(serial_t *obj) {
331 obj->uart->LCR |= (1 << 6);
334 void serial_break_clear(serial_t *obj) {
335 obj->uart->LCR &= ~(1 << 6);