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
21 #include "serial_api.h"
24 #include "mbed_error.h"
26 /******************************************************************************
28 ******************************************************************************/
29 static const PinMap PinMap_UART_TX[] = {
45 static const PinMap PinMap_UART_RX[] = {
62 static uint32_t serial_irq_ids[UART_NUM] = {0};
63 static uart_irq_handler irq_handler;
65 int stdio_uart_inited = 0;
68 void serial_init(serial_t *obj, PinName tx, PinName rx) {
69 int is_stdio_uart = 0;
71 // determine the UART to use
72 UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
73 UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
74 UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
75 MBED_ASSERT((int)uart != NC);
77 obj->uart = (LPC_UART_TypeDef *)uart;
80 case UART_0: LPC_SC->PCONP |= 1 << 3; break;
81 case UART_1: LPC_SC->PCONP |= 1 << 4; break;
82 case UART_2: LPC_SC->PCONP |= 1 << 24; break;
83 case UART_3: LPC_SC->PCONP |= 1 << 25; break;
84 case UART_4: LPC_SC->PCONP |= 1 << 8; break;
87 // enable fifos and default rx trigger level
88 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
89 | 0 << 1 // Rx Fifo Reset
90 | 0 << 2 // Tx Fifo Reset
91 | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
94 obj->uart->IER = 0 << 0 // Rx Data available irq enable
95 | 0 << 1 // Tx Fifo empty irq enable
96 | 0 << 2; // Rx Line Status irq enable
98 // set default baud rate and format
99 serial_baud (obj, 9600);
100 serial_format(obj, 8, ParityNone, 1);
102 // pinout the chosen uart
103 pinmap_pinout(tx, PinMap_UART_TX);
104 pinmap_pinout(rx, PinMap_UART_RX);
106 // set rx/tx pins in PullUp mode
108 pin_mode(tx, PullUp);
111 pin_mode(rx, PullUp);
115 case UART_0: obj->index = 0; break;
116 case UART_1: obj->index = 1; break;
117 case UART_2: obj->index = 2; break;
118 case UART_3: obj->index = 3; break;
119 case UART_4: obj->index = 4; break;
122 is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
125 stdio_uart_inited = 1;
126 memcpy(&stdio_uart, obj, sizeof(serial_t));
130 void serial_free(serial_t *obj) {
131 serial_irq_ids[obj->index] = 0;
135 // set the baud rate, taking in to account the current SystemFrequency
136 void serial_baud(serial_t *obj, int baudrate) {
137 uint32_t PCLK = PeripheralClock;
139 // First we check to see if the basic divide with no DivAddVal/MulVal
140 // ratio gives us an integer result. If it does, we set DivAddVal = 0,
141 // MulVal = 1. Otherwise, we search the valid ratio value range to find
142 // the closest match. This could be more elegant, using search methods
143 // and/or lookup tables, but the brute force method is not that much
144 // slower, and is more maintainable.
145 uint16_t DL = PCLK / (16 * baudrate);
147 uint8_t DivAddVal = 0;
152 if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
153 int err_best = baudrate, b;
154 for (mv = 1; mv < 16 && !hit; mv++)
156 for (dav = 0; dav < mv; dav++)
158 // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
159 // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
160 // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
161 // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
162 // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
164 if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
165 dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
166 else // 2 bits headroom, use more precision
167 dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
169 // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
173 // datasheet says if dav > 0 then DL must be >= 2
174 if ((dav > 0) && (dlv < 2))
177 // integer rearrangement of the baudrate equation (with rounding)
178 b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
180 // check to see how we went
181 b = abs(b - baudrate);
200 // set LCR[DLAB] to enable writing to divider registers
201 obj->uart->LCR |= (1 << 7);
203 // set divider values
204 obj->uart->DLM = (DL >> 8) & 0xFF;
205 obj->uart->DLL = (DL >> 0) & 0xFF;
206 obj->uart->FDR = (uint32_t) DivAddVal << 0
207 | (uint32_t) MulVal << 4;
210 obj->uart->LCR &= ~(1 << 7);
213 void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
214 MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
215 MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
216 MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
217 (parity == ParityForced1) || (parity == ParityForced0));
222 int parity_enable, parity_select;
224 case ParityNone: parity_enable = 0; parity_select = 0; break;
225 case ParityOdd : parity_enable = 1; parity_select = 0; break;
226 case ParityEven: parity_enable = 1; parity_select = 1; break;
227 case ParityForced1: parity_enable = 1; parity_select = 2; break;
228 case ParityForced0: parity_enable = 1; parity_select = 3; break;
233 obj->uart->LCR = data_bits << 0
236 | parity_select << 4;
239 /******************************************************************************
240 * INTERRUPTS HANDLING
241 ******************************************************************************/
242 static inline void uart_irq(uint32_t iir, uint32_t index) {
243 // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
246 case 1: irq_type = TxIrq; break;
247 case 2: irq_type = RxIrq; break;
251 if (serial_irq_ids[index] != 0)
252 irq_handler(serial_irq_ids[index], irq_type);
255 void uart0_irq() {uart_irq((LPC_UART0->IIR >> 1) & 0x7, 0);}
256 void uart1_irq() {uart_irq((LPC_UART1->IIR >> 1) & 0x7, 1);}
257 void uart2_irq() {uart_irq((LPC_UART2->IIR >> 1) & 0x7, 2);}
258 void uart3_irq() {uart_irq((LPC_UART3->IIR >> 1) & 0x7, 3);}
259 void uart4_irq() {uart_irq((LPC_UART4->IIR >> 1) & 0x7, 4);}
261 void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
262 irq_handler = handler;
263 serial_irq_ids[obj->index] = id;
266 void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
267 IRQn_Type irq_n = (IRQn_Type)0;
269 switch ((int)obj->uart) {
270 case UART_0: irq_n=UART0_IRQn; vector = (uint32_t)&uart0_irq; break;
271 case UART_1: irq_n=UART1_IRQn; vector = (uint32_t)&uart1_irq; break;
272 case UART_2: irq_n=UART2_IRQn; vector = (uint32_t)&uart2_irq; break;
273 case UART_3: irq_n=UART3_IRQn; vector = (uint32_t)&uart3_irq; break;
274 case UART_4: irq_n=UART4_IRQn; vector = (uint32_t)&uart4_irq; break;
278 obj->uart->IER |= 1 << irq;
279 NVIC_SetVector(irq_n, vector);
280 NVIC_EnableIRQ(irq_n);
282 int all_disabled = 0;
283 SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
284 obj->uart->IER &= ~(1 << irq);
285 all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
287 NVIC_DisableIRQ(irq_n);
291 /******************************************************************************
293 ******************************************************************************/
294 int serial_getc(serial_t *obj) {
295 while (!serial_readable(obj));
296 return obj->uart->RBR;
299 void serial_putc(serial_t *obj, int c) {
300 while (!serial_writable(obj));
304 int serial_readable(serial_t *obj) {
305 return obj->uart->LSR & 0x01;
308 int serial_writable(serial_t *obj) {
309 return obj->uart->LSR & 0x20;
312 void serial_clear(serial_t *obj) {
313 obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
314 | 1 << 1 // rx FIFO reset
315 | 1 << 2 // tx FIFO reset
316 | 0 << 6; // interrupt depth
319 void serial_pinout_tx(PinName tx) {
320 pinmap_pinout(tx, PinMap_UART_TX);
323 void serial_break_set(serial_t *obj) {
324 obj->uart->LCR |= (1 << 6);
327 void serial_break_clear(serial_t *obj) {
328 obj->uart->LCR &= ~(1 << 6);