restructuring

F0:F030,F042,F072/uart_blink/usart.c

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+/*
+ * usart.c
+ *
+ * Copyright 2017 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include "usart.h"
+#include <string.h> // memcpy
+
+extern volatile uint32_t Tms;
+
+static int datalen[2] = {0,0}; // received data line length (including '\n')
+
+int linerdy = 0,        // received data ready
+    dlen = 0,           // length of data (including '\n') in current buffer
+    bufovr = 0,         // input buffer overfull
+    txrdy = 1,          // transmission done
+    txdlen = 0          // length of transmitted data
+;
+
+static int  rbufno = 0, // current rbuf number
+            txnum = 0;  // current number of transmitted symbol in tbuf
+static char rbuf[2][UARTBUFSZ], tbuf[UARTBUFSZ]; // receive & transmit buffers
+static char *recvdata = NULL;
+
+void USART1_config(){
+    /* Enable the peripheral clock of GPIOA */
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
+    /* GPIO configuration for USART1 signals */
+    /* (1) Select AF mode (10) on PA9 and PA10 */
+    /* (2) AF1 for USART1 signals */
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER9|GPIO_MODER_MODER10))\
+                | (GPIO_MODER_MODER9_1 | GPIO_MODER_MODER10_1); /* (1) */
+    GPIOA->AFR[1] = (GPIOA->AFR[1] &~ (GPIO_AFRH_AFRH1 | GPIO_AFRH_AFRH2))\
+                | (1 << (1 * 4)) | (1 << (2 * 4)); /* (2) */
+    /* Enable the peripheral clock USART1 */
+    RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
+    /* Configure USART1 */
+    /* (1) oversampling by 16, 115200 baud */
+    /* (2) 8 data bit, 1 start bit, 1 stop bit, no parity */
+    USART1->BRR = 480000 / 1152; /* (1) */
+    USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; /* (2) */
+    /* polling idle frame Transmission */
+    while(!(USART1->ISR & USART_ISR_TC)){}
+    USART1->ICR |= USART_ICR_TCCF;/* clear TC flag */
+    USART1->CR1 |= USART_CR1_TCIE | USART_CR1_TXEIE | USART_CR1_RXNEIE;/* enable TC, TXE & RXNE interrupt */
+    /* Configure IT */
+    /* (3) Set priority for USART1_IRQn */
+    /* (4) Enable USART1_IRQn */
+    NVIC_SetPriority(USART1_IRQn, 0); /* (3) */
+    NVIC_EnableIRQ(USART1_IRQn); /* (4) */
+}
+
+void usart1_isr(){
+    #ifdef CHECK_TMOUT
+    static uint32_t tmout = 0;
+    #endif
+    if(USART1->ISR & USART_ISR_TC){ // Transmission complete
+        USART1->ICR |= USART_ICR_TCCF; /* Clear transfer complete flag */
+        txrdy = 1;
+    }
+    if(USART1->ISR & USART_ISR_TXE){ // TX emty - send next char
+        // clear by writing to TDR
+        if(txnum < txdlen){
+            USART1->TDR = tbuf[txnum++];
+        }else
+        USART1->CR1 &= ~USART_CR1_TXEIE; // turn off interrupt
+    }
+    if(USART1->ISR & USART_ISR_RXNE){ // RX not emty - receive next char
+        #ifdef CHECK_TMOUT
+        if(tmout && Tms >= tmout){ // set overflow flag
+            bufovr = 1;
+            datalen[rbufno] = 0;
+        }
+        tmout = Tms + TIMEOUT_MS;
+        if(!tmout) tmout = 1; // prevent 0
+        #endif
+        // read RDR clears flag
+        uint8_t rb = USART1->RDR;
+        if(datalen[rbufno] < UARTBUFSZ){ // put next char into buf
+            rbuf[rbufno][datalen[rbufno]++] = rb;
+            if(rb == '\n'){ // got newline - line ready
+                linerdy = 1;
+                dlen = datalen[rbufno];
+                recvdata = rbuf[rbufno];
+                // prepare other buffer
+                rbufno = !rbufno;
+                datalen[rbufno] = 0;
+                #ifdef CHECK_TMOUT
+                // clear timeout at line end
+                tmout = 0;
+                #endif
+            }
+        }else{ // buffer overrun
+            bufovr = 1;
+            datalen[rbufno] = 0;
+            #ifdef CHECK_TMOUT
+            tmout = 0;
+            #endif
+        }
+    }
+}
+
+/**
+ * return length of received data (without trailing zero
+ */
+int usart1_getline(char **line){
+    if(bufovr){
+        bufovr = 0;
+        linerdy = 0;
+        return 0;
+    }
+    *line = recvdata;
+    linerdy = 0;
+    return dlen;
+}
+
+TXstatus usart1_send(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    if(len > UARTBUFSZ) return STR_TOO_LONG;
+    txrdy = 0;
+    txdlen = len;
+    memcpy(tbuf, str, len);
+    txnum = 0;
+    USART1->CR1 |= USART_CR1_TXEIE; // allow IRQ
+    return ALL_OK;
+}
+
+TXstatus usart1_send_blocking(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    int i;
+    for(i = 0; i < len; ++i){
+        USART1->TDR = *str++;
+        while(!(USART1->ISR & USART_ISR_TXE));
+    }
+    txrdy = 1;
+    return ALL_OK;
+}