Lee Kai Xuan
mbed-os
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erkin yucel
Diff: targets/TARGET_NXP/TARGET_LPC2460/serial_api.c
- Revision:
- 0:f269e3021894
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC2460/serial_api.c Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,338 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2015 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// math.h required for floating point operations for baud rate calculation
+#include "mbed_assert.h"
+#include <math.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "serial_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+
+/******************************************************************************
+ * INITIALIZATION
+ ******************************************************************************/
+#define UART_NUM 4
+
+static const PinMap PinMap_UART_TX[] = {
+ {P0_0, UART_3, 2},
+ {P0_2, UART_0, 1},
+ {P0_10, UART_2, 1},
+ {P0_15, UART_1, 1},
+ {P0_25, UART_3, 3},
+ {P2_0 , UART_1, 2},
+ {P2_8 , UART_2, 2},
+ {P4_28, UART_3, 3},
+ {NC , NC , 0}
+};
+
+static const PinMap PinMap_UART_RX[] = {
+ {P0_1 , UART_3, 2},
+ {P0_3 , UART_0, 1},
+ {P0_11, UART_2, 1},
+ {P0_16, UART_1, 1},
+ {P0_26, UART_3, 3},
+ {P2_1 , UART_1, 2},
+ {P2_9 , UART_2, 2},
+ {P4_29, UART_3, 3},
+ {NC , NC , 0}
+};
+
+static uint32_t serial_irq_ids[UART_NUM] = {0};
+static uart_irq_handler irq_handler;
+
+int stdio_uart_inited = 0;
+serial_t stdio_uart;
+
+void serial_init(serial_t *obj, PinName tx, PinName rx) {
+ int is_stdio_uart = 0;
+
+ // determine the UART to use
+ UARTName uart_tx = (UARTName)pinmap_peripheral(tx, PinMap_UART_TX);
+ UARTName uart_rx = (UARTName)pinmap_peripheral(rx, PinMap_UART_RX);
+ UARTName uart = (UARTName)pinmap_merge(uart_tx, uart_rx);
+ MBED_ASSERT((int)uart != NC);
+
+ obj->uart = (LPC_UART_TypeDef *)uart;
+ // enable power
+ switch (uart) {
+ case UART_0: LPC_SC->PCONP |= 1 << 3; break;
+ case UART_1: LPC_SC->PCONP |= 1 << 4; break;
+ case UART_2: LPC_SC->PCONP |= 1 << 24; break;
+ case UART_3: LPC_SC->PCONP |= 1 << 25; break;
+ }
+
+ // enable fifos and default rx trigger level
+ obj->uart->FCR = 1 << 0 // FIFO Enable - 0 = Disables, 1 = Enabled
+ | 0 << 1 // Rx Fifo Reset
+ | 0 << 2 // Tx Fifo Reset
+ | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
+
+ // disable irqs
+ obj->uart->IER = 0 << 0 // Rx Data available irq enable
+ | 0 << 1 // Tx Fifo empty irq enable
+ | 0 << 2; // Rx Line Status irq enable
+
+ // set default baud rate and format
+ serial_baud (obj, 9600);
+ serial_format(obj, 8, ParityNone, 1);
+
+ // pinout the chosen uart
+ pinmap_pinout(tx, PinMap_UART_TX);
+ pinmap_pinout(rx, PinMap_UART_RX);
+
+ // set rx/tx pins in PullUp mode
+ if (tx != NC) {
+ pin_mode(tx, PullUp);
+ }
+ if (rx != NC) {
+ pin_mode(rx, PullUp);
+ }
+
+ switch (uart) {
+ case UART_0: obj->index = 0; break;
+ case UART_1: obj->index = 1; break;
+ case UART_2: obj->index = 2; break;
+ case UART_3: obj->index = 3; break;
+ }
+
+ is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
+
+ if (is_stdio_uart) {
+ stdio_uart_inited = 1;
+ memcpy(&stdio_uart, obj, sizeof(serial_t));
+ }
+}
+
+void serial_free(serial_t *obj) {
+ serial_irq_ids[obj->index] = 0;
+}
+
+// serial_baud
+// set the baud rate, taking in to account the current SystemFrequency
+void serial_baud(serial_t *obj, int baudrate) {
+ MBED_ASSERT((int)obj->uart <= UART_3);
+ // The LPC2300 and LPC1700 have a divider and a fractional divider to control the
+ // baud rate. The formula is:
+ //
+ // Baudrate = (1 / PCLK) * 16 * DL * (1 + DivAddVal / MulVal)
+ // where:
+ // 1 < MulVal <= 15
+ // 0 <= DivAddVal < 14
+ // DivAddVal < MulVal
+ //
+ // set pclk to /1
+ switch ((int)obj->uart) {
+ case UART_0: LPC_SC->PCLKSEL0 &= ~(0x3 << 6); LPC_SC->PCLKSEL0 |= (0x1 << 6); break;
+ case UART_1: LPC_SC->PCLKSEL0 &= ~(0x3 << 8); LPC_SC->PCLKSEL0 |= (0x1 << 8); break;
+ case UART_2: LPC_SC->PCLKSEL1 &= ~(0x3 << 16); LPC_SC->PCLKSEL1 |= (0x1 << 16); break;
+ case UART_3: LPC_SC->PCLKSEL1 &= ~(0x3 << 18); LPC_SC->PCLKSEL1 |= (0x1 << 18); break;
+ default: break;
+ }
+
+ uint32_t PCLK = SystemCoreClock;
+
+ // First we check to see if the basic divide with no DivAddVal/MulVal
+ // ratio gives us an integer result. If it does, we set DivAddVal = 0,
+ // MulVal = 1. Otherwise, we search the valid ratio value range to find
+ // the closest match. This could be more elegant, using search methods
+ // and/or lookup tables, but the brute force method is not that much
+ // slower, and is more maintainable.
+ uint16_t DL = PCLK / (16 * baudrate);
+
+ uint8_t DivAddVal = 0;
+ uint8_t MulVal = 1;
+ int hit = 0;
+ uint16_t dlv;
+ uint8_t mv, dav;
+ if ((PCLK % (16 * baudrate)) != 0) { // Checking for zero remainder
+ int err_best = baudrate, b;
+ for (mv = 1; mv < 16 && !hit; mv++)
+ {
+ for (dav = 0; dav < mv; dav++)
+ {
+ // baudrate = PCLK / (16 * dlv * (1 + (DivAdd / Mul))
+ // solving for dlv, we get dlv = mul * PCLK / (16 * baudrate * (divadd + mul))
+ // mul has 4 bits, PCLK has 27 so we have 1 bit headroom which can be used for rounding
+ // for many values of mul and PCLK we have 2 or more bits of headroom which can be used to improve precision
+ // note: X / 32 doesn't round correctly. Instead, we use ((X / 16) + 1) / 2 for correct rounding
+
+ if ((mv * PCLK * 2) & 0x80000000) // 1 bit headroom
+ dlv = ((((2 * mv * PCLK) / (baudrate * (dav + mv))) / 16) + 1) / 2;
+ else // 2 bits headroom, use more precision
+ dlv = ((((4 * mv * PCLK) / (baudrate * (dav + mv))) / 32) + 1) / 2;
+
+ // datasheet says if DLL==DLM==0, then 1 is used instead since divide by zero is ungood
+ if (dlv == 0)
+ dlv = 1;
+
+ // datasheet says if dav > 0 then DL must be >= 2
+ if ((dav > 0) && (dlv < 2))
+ dlv = 2;
+
+ // integer rearrangement of the baudrate equation (with rounding)
+ b = ((PCLK * mv / (dlv * (dav + mv) * 8)) + 1) / 2;
+
+ // check to see how we went
+ b = abs(b - baudrate);
+ if (b < err_best)
+ {
+ err_best = b;
+
+ DL = dlv;
+ MulVal = mv;
+ DivAddVal = dav;
+
+ if (b == baudrate)
+ {
+ hit = 1;
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ // set LCR[DLAB] to enable writing to divider registers
+ obj->uart->LCR |= (1 << 7);
+
+ // set divider values
+ obj->uart->DLM = (DL >> 8) & 0xFF;
+ obj->uart->DLL = (DL >> 0) & 0xFF;
+ obj->uart->FDR = (uint32_t) DivAddVal << 0
+ | (uint32_t) MulVal << 4;
+
+ // clear LCR[DLAB]
+ obj->uart->LCR &= ~(1 << 7);
+}
+
+void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
+ MBED_ASSERT((stop_bits == 1) || (stop_bits == 2)); // 0: 1 stop bits, 1: 2 stop bits
+ MBED_ASSERT((data_bits > 4) && (data_bits < 9)); // 0: 5 data bits ... 3: 8 data bits
+ MBED_ASSERT((parity == ParityNone) || (parity == ParityOdd) || (parity == ParityEven) ||
+ (parity == ParityForced1) || (parity == ParityForced0));
+
+ stop_bits -= 1;
+ data_bits -= 5;
+
+ int parity_enable = 0, parity_select = 0;
+ switch (parity) {
+ case ParityNone: parity_enable = 0; parity_select = 0; break;
+ case ParityOdd : parity_enable = 1; parity_select = 0; break;
+ case ParityEven: parity_enable = 1; parity_select = 1; break;
+ case ParityForced1: parity_enable = 1; parity_select = 2; break;
+ case ParityForced0: parity_enable = 1; parity_select = 3; break;
+ default:
+ break;
+ }
+
+ obj->uart->LCR = data_bits << 0
+ | stop_bits << 2
+ | parity_enable << 3
+ | parity_select << 4;
+}
+
+/******************************************************************************
+ * INTERRUPTS HANDLING
+ ******************************************************************************/
+static inline void uart_irq(uint32_t iir, uint32_t index) {
+ // [Chapter 14] LPC17xx UART0/2/3: UARTn Interrupt Handling
+ SerialIrq irq_type;
+ switch (iir) {
+ case 1: irq_type = TxIrq; break;
+ case 2: irq_type = RxIrq; break;
+ default: return;
+ }
+
+ if (serial_irq_ids[index] != 0){
+ irq_handler(serial_irq_ids[index], irq_type);
+ }
+}
+
+void uart0_irq() {uart_irq((LPC_UART0->IIR >> 1) & 0x7, 0);}
+void uart1_irq() {uart_irq((LPC_UART1->IIR >> 1) & 0x7, 1);}
+void uart2_irq() {uart_irq((LPC_UART2->IIR >> 1) & 0x7, 2);}
+void uart3_irq() {uart_irq((LPC_UART3->IIR >> 1) & 0x7, 3);}
+
+void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
+ irq_handler = handler;
+ serial_irq_ids[obj->index] = id;
+}
+
+void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
+ IRQn_Type irq_n = (IRQn_Type)0;
+ uint32_t vector = 0;
+ switch ((int)obj->uart) {
+ case UART_0: irq_n=UART0_IRQn; vector = (uint32_t)&uart0_irq; break;
+ case UART_1: irq_n=UART1_IRQn; vector = (uint32_t)&uart1_irq; break;
+ case UART_2: irq_n=UART2_IRQn; vector = (uint32_t)&uart2_irq; break;
+ case UART_3: irq_n=UART3_IRQn; vector = (uint32_t)&uart3_irq; break;
+ }
+
+ if (enable) {
+ obj->uart->IER |= 1 << irq;
+ NVIC_SetVector(irq_n, vector);
+ NVIC_EnableIRQ(irq_n);
+ } else { // disable
+ int all_disabled = 0;
+ SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
+ obj->uart->IER &= ~(1 << irq);
+ all_disabled = (obj->uart->IER & (1 << other_irq)) == 0;
+ if (all_disabled)
+ NVIC_DisableIRQ(irq_n);
+ }
+}
+
+/******************************************************************************
+ * READ/WRITE
+ ******************************************************************************/
+int serial_getc(serial_t *obj) {
+ while (!serial_readable(obj));
+ return obj->uart->RBR;
+}
+
+void serial_putc(serial_t *obj, int c) {
+ while (!serial_writable(obj));
+ obj->uart->THR = c;
+}
+
+int serial_readable(serial_t *obj) {
+ return obj->uart->LSR & 0x01;
+}
+
+int serial_writable(serial_t *obj) {
+ return obj->uart->LSR & 0x20;
+}
+
+void serial_clear(serial_t *obj) {
+ obj->uart->FCR = 1 << 1 // rx FIFO reset
+ | 1 << 2 // tx FIFO reset
+ | 0 << 6; // interrupt depth
+}
+
+void serial_pinout_tx(PinName tx) {
+ pinmap_pinout(tx, PinMap_UART_TX);
+}
+
+void serial_break_set(serial_t *obj) {
+ obj->uart->LCR |= (1 << 6);
+}
+
+void serial_break_clear(serial_t *obj) {
+ obj->uart->LCR &= ~(1 << 6);
+}
+