Diff: targets/TARGET_NXP/TARGET_LPC81X/serial_api.c

Revision:

0:f269e3021894

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NXP/TARGET_LPC81X/serial_api.c	Sun Oct 23 15:10:02 2016 +0000
@@ -0,0 +1,330 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 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 "serial_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+#include "mbed_error.h"
+
+/******************************************************************************
+ * INITIALIZATION
+ ******************************************************************************/
+#define UART_NUM    3
+
+static const SWM_Map SWM_UART_TX[] = {
+    {0, 0},
+    {1, 8},
+    {2, 16},
+};
+
+static const SWM_Map SWM_UART_RX[] = {
+    {0, 8},
+    {1, 16},
+    {2, 24},
+};
+
+static const SWM_Map SWM_UART_RTS[] = {
+    {0, 16},
+    {1, 24},
+    {3, 0},
+};
+ 
+static const SWM_Map SWM_UART_CTS[] = {
+    {0, 24},
+    {2, 0},
+    {3, 8}
+};
+
+// bit flags for used UARTs
+static unsigned char uart_used = 0;
+static int get_available_uart(void) {
+    int i;
+    for (i=0; i<3; i++) {
+        if ((uart_used & (1 << i)) == 0)
+            return i;
+    }
+    return -1;
+}
+
+#define UART_EN       (0x01<<0)
+
+#define CTS_DELTA     (0x01<<5)
+#define RXBRK         (0x01<<10)
+#define DELTA_RXBRK   (0x01<<11)
+
+#define RXRDY         (0x01<<0)
+#define TXRDY         (0x01<<2)
+
+#define TXBRKEN       (0x01<<1)
+#define CTSEN         (0x01<<9)
+
+static uint32_t UARTSysClk;
+
+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;
+    
+    int uart_n = get_available_uart();
+    if (uart_n == -1) {
+        error("No available UART");
+    }
+    obj->index = uart_n;
+    obj->uart = (LPC_USART_TypeDef *)(LPC_USART0_BASE + (0x4000 * uart_n));
+    uart_used |= (1 << uart_n);
+    
+    const SWM_Map *swm;
+    uint32_t regVal;
+    
+    swm = &SWM_UART_TX[uart_n];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (tx   << swm->offset);
+    
+    swm = &SWM_UART_RX[uart_n];
+    regVal = LPC_SWM->PINASSIGN[swm->n] & ~(0xFF << swm->offset);
+    LPC_SWM->PINASSIGN[swm->n] = regVal |  (rx   << swm->offset);
+    
+    /* uart clock divided by 1 */
+    LPC_SYSCON->UARTCLKDIV = 1;
+    
+    /* disable uart interrupts */
+    NVIC_DisableIRQ((IRQn_Type)(UART0_IRQn + uart_n));
+    
+    /* Enable UART clock */
+    LPC_SYSCON->SYSAHBCLKCTRL |= (1 << (14 + uart_n));
+    
+    /* Peripheral reset control to UART, a "1" bring it out of reset. */
+    LPC_SYSCON->PRESETCTRL &= ~(0x1 << (3 + uart_n));
+    LPC_SYSCON->PRESETCTRL |=  (0x1 << (3 + uart_n));
+
+    // Derive UART Clock from MainClock    
+    UARTSysClk = MainClock / LPC_SYSCON->UARTCLKDIV;    
+
+    // set default baud rate and format
+    serial_baud  (obj, 9600);
+    serial_format(obj, 8, ParityNone, 1);
+    
+    /* Clear all status bits. */
+    obj->uart->STAT = CTS_DELTA | DELTA_RXBRK;
+    
+    /* enable uart interrupts */
+    NVIC_EnableIRQ((IRQn_Type)(UART0_IRQn + uart_n));
+    
+    /* Enable UART interrupt */
+    // obj->uart->INTENSET = RXRDY | TXRDY | DELTA_RXBRK;
+    
+    /* Enable UART */
+    obj->uart->CFG |= UART_EN;
+    
+    is_stdio_uart = ((tx == USBTX) && (rx == USBRX));
+    
+    if (is_stdio_uart) {
+        stdio_uart_inited = 1;
+        memcpy(&stdio_uart, obj, sizeof(serial_t));
+    }
+}
+
+void serial_free(serial_t *obj) {
+    uart_used &= ~(1 << obj->index);
+    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) {
+    /* Integer divider:
+         BRG = UARTSysClk/(Baudrate * 16) - 1
+       
+       Frational divider:
+         FRG = ((UARTSysClk / (Baudrate * 16 * (BRG + 1))) - 1)
+       
+       where
+         FRG = (LPC_SYSCON->UARTFRDADD + 1) / (LPC_SYSCON->UARTFRDSUB + 1)
+       
+       (1) The easiest way is set SUB value to 256, -1 encoded, thus SUB
+           register is 0xFF.
+       (2) In ADD register value, depending on the value of UartSysClk,
+           baudrate, BRG register value, and SUB register value, be careful
+           about the order of multiplier and divider and make sure any
+           multiplier doesn't exceed 32-bit boundary and any divider doesn't get
+           down below one(integer 0).
+       (3) ADD should be always less than SUB.
+    */
+    obj->uart->BRG = UARTSysClk / 16 / baudrate - 1;
+    
+    LPC_SYSCON->UARTFRGDIV = 0xFF;
+    LPC_SYSCON->UARTFRGMULT = ( ((UARTSysClk / 16) * (LPC_SYSCON->UARTFRGDIV + 1)) /
+                                (baudrate * (obj->uart->BRG + 1))
+                              ) - (LPC_SYSCON->UARTFRGDIV + 1);
+
+}
+
+void serial_format(serial_t *obj, int data_bits, SerialParity parity, int stop_bits) {
+    // 0: 1 stop bits, 1: 2 stop bits
+    MBED_ASSERT((stop_bits == 1) || (stop_bits == 2));
+    MBED_ASSERT((data_bits > 6) && (data_bits < 10)); // 0: 7 data bits ... 2: 9 data bits
+    MBED_ASSERT((parity == ParityNone) || (parity == ParityEven) || (parity == ParityOdd));
+    stop_bits -= 1;
+    data_bits -= 7;
+    
+    int paritysel;
+    switch (parity) {
+        case ParityNone: paritysel = 0; break;
+        case ParityEven: paritysel = 2; break;
+        case ParityOdd : paritysel = 3; break;
+        default:
+            break;
+    }
+
+    // First disable the the usart as described in documentation and then enable while updating CFG
+
+    // 24.6.1 USART Configuration register
+    // Remark: If software needs to change configuration values, the following sequence should
+    // be used: 1) Make sure the USART is not currently sending or receiving data. 2) Disable
+    // the USART by writing a 0 to the Enable bit (0 may be written to the entire register). 3)
+    // Write the new configuration value, with the ENABLE bit set to 1.
+    obj->uart->CFG &= ~(1 << 0);
+
+    obj->uart->CFG = (1 << 0) // this will enable the usart
+                   | (data_bits << 2)
+                   | (paritysel << 4)
+                   | (stop_bits << 6);
+}
+
+/******************************************************************************
+ * 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_USART0->STAT & (1 << 2)) ? 2 : 1, 0);}
+void uart1_irq() {uart_irq((LPC_USART1->STAT & (1 << 2)) ? 2 : 1, 1);}
+void uart2_irq() {uart_irq((LPC_USART2->STAT & (1 << 2)) ? 2 : 1, 2);}
+
+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 LPC_USART0_BASE: irq_n=UART0_IRQn; vector = (uint32_t)&uart0_irq; break;
+        case LPC_USART1_BASE: irq_n=UART1_IRQn; vector = (uint32_t)&uart1_irq; break;
+        case LPC_USART2_BASE: irq_n=UART2_IRQn; vector = (uint32_t)&uart2_irq; break;
+    }
+    
+    if (enable) {
+        obj->uart->INTENSET = (1 << ((irq == RxIrq) ? 0 : 2));
+        NVIC_SetVector(irq_n, vector);
+        NVIC_EnableIRQ(irq_n);
+    } else { // disable
+        int all_disabled = 0;
+        SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
+        obj->uart->INTENSET &= ~(1 << ((irq == RxIrq) ? 0 : 2));
+        all_disabled = (obj->uart->INTENSET & (1 << ((other_irq == RxIrq) ? 0 : 2))) == 0;
+        if (all_disabled)
+            NVIC_DisableIRQ(irq_n);
+    }
+}
+
+/******************************************************************************
+ * READ/WRITE
+ ******************************************************************************/
+int serial_getc(serial_t *obj) {
+    while (!serial_readable(obj));
+    return obj->uart->RXDATA;
+}
+
+void serial_putc(serial_t *obj, int c) {
+    while (!serial_writable(obj));
+    obj->uart->TXDATA = c;
+}
+
+int serial_readable(serial_t *obj) {
+    return obj->uart->STAT & RXRDY;
+}
+
+int serial_writable(serial_t *obj) {
+    return obj->uart->STAT & TXRDY;
+}
+
+void serial_clear(serial_t *obj) {
+    // [TODO]
+}
+
+void serial_pinout_tx(PinName tx) {
+    
+}
+
+void serial_break_set(serial_t *obj) {
+    obj->uart->CTRL |= TXBRKEN;
+}
+
+void serial_break_clear(serial_t *obj) {
+    obj->uart->CTRL &= ~TXBRKEN;
+}
+
+void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, PinName txflow) {
+    const SWM_Map *swm_rts, *swm_cts;
+    uint32_t regVal_rts, regVal_cts;
+    
+    swm_rts = &SWM_UART_RTS[obj->index];
+    swm_cts = &SWM_UART_CTS[obj->index];
+    regVal_rts = LPC_SWM->PINASSIGN[swm_rts->n] & ~(0xFF << swm_rts->offset);
+    regVal_cts = LPC_SWM->PINASSIGN[swm_cts->n] & ~(0xFF << swm_cts->offset);
+    
+    if (FlowControlNone == type) {
+        LPC_SWM->PINASSIGN[swm_rts->n] = regVal_rts | (0xFF << swm_rts->offset);
+        LPC_SWM->PINASSIGN[swm_cts->n] = regVal_cts | (0xFF << swm_cts->offset);
+        obj->uart->CFG &= ~CTSEN;
+        return;
+    }
+    if ((FlowControlRTS == type || FlowControlRTSCTS == type) && (rxflow != NC)) {
+        LPC_SWM->PINASSIGN[swm_rts->n] = regVal_rts | (rxflow << swm_rts->offset);
+        if (FlowControlRTS == type) {
+            LPC_SWM->PINASSIGN[swm_cts->n] = regVal_cts | (0xFF << swm_cts->offset);
+            obj->uart->CFG &= ~CTSEN;
+        }
+    }
+    if ((FlowControlCTS == type || FlowControlRTSCTS == type) && (txflow != NC)) {
+        LPC_SWM->PINASSIGN[swm_cts->n] = regVal_cts | (txflow << swm_cts->offset);
+        obj->uart->CFG |= CTSEN;
+        if (FlowControlCTS == type) {
+            LPC_SWM->PINASSIGN[swm_rts->n] = regVal_rts | (0xFF << swm_rts->offset);
+        }
+    }
+}
+