Add canUART for STM32F103

F1:F103/canUART/usart.c

@@ -0,0 +1,140 @@
+/*
+ * This file is part of the canuart project.
+ * Copyright 2022 Edward V. Emelianov <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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "stm32f1.h"
+#include "usart.h"
+
+extern volatile uint32_t Tms;
+static volatile int idatalen[2] = {0,0}; // received data line length (including '\n')
+static volatile int odatalen[2] = {0,0};
+
+volatile int usart_txrdy = 1;   // transmission done
+
+static volatile int usart_linerdy = 0   // received data ready
+    ,dlen = 0                           // length of data (including '\n') in current buffer
+    ,usart_bufovr = 0                   // input buffer overfull
+
+;
+
+int rbufno = 0, tbufno = 0; // current rbuf/tbuf numbers
+static char rbuf[2][UARTBUFSZI], tbuf[2][UARTBUFSZO]; // receive & transmit buffers
+static char *recvdata = NULL;
+
+/**
+ * return length of received data (without trailing zero)
+ */
+int usart_getline(char **line){
+    if(usart_bufovr){
+        usart_bufovr = 0;
+        usart_linerdy = 0;
+        return -1;
+    }
+    if(!usart_linerdy) return 0;
+    *line = recvdata;
+    usart_linerdy = 0;
+    int x = dlen;
+    dlen = 0;
+    return x;
+}
+
+// transmit current tbuf and swap buffers
+void usart_transmit(){
+    register int l = odatalen[tbufno];
+    if(!l) return;
+    uint32_t tmout = 16000000;
+    while(!usart_txrdy){if(--tmout == 0) return;}; // wait for previos buffer transmission
+    usart_txrdy = 0;
+    odatalen[tbufno] = 0;
+    DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel4->CMAR = (uint32_t) tbuf[tbufno]; // mem
+    DMA1_Channel4->CNDTR = l;
+    DMA1_Channel4->CCR |= DMA_CCR_EN;
+    tbufno = !tbufno;
+}
+
+void usart_putchar(const char ch){
+    if(odatalen[tbufno] == UARTBUFSZO) usart_transmit();
+    tbuf[tbufno][odatalen[tbufno]++] = ch;
+}
+
+void usart_send(const char *str){
+    while(*str){
+        if(odatalen[tbufno] == UARTBUFSZO) usart_transmit();
+        tbuf[tbufno][odatalen[tbufno]++] = *str++;
+    }
+}
+
+/*
+ * USART speed: baudrate = Fck/(USARTDIV)
+ * USARTDIV stored in USART->BRR
+ *
+ * for 72MHz USARTDIV=72000/f(kboud); so for 115200 USARTDIV=72000/115.2=625 -> BRR=0x271
+ *         9600: BRR = 7500 (0x1D4C)
+ */
+
+void usart_setup(){
+    uint32_t tmout = 16000000;
+    // PA9 - Tx, PA10 - Rx
+    RCC->APB2ENR |= RCC_APB2ENR_IOPAEN | RCC_APB2ENR_USART1EN | RCC_APB2ENR_AFIOEN;
+    RCC->AHBENR |= RCC_AHBENR_DMA1EN;
+    GPIOA->CRH = CRH(9, CNF_AFPP|MODE_NORMAL) | CRH(10, CNF_FLINPUT|MODE_INPUT);
+
+    // USART1 Tx DMA - Channel4 (Rx - channel 5)
+    DMA1_Channel4->CPAR = (uint32_t) &USART1->DR; // periph
+    DMA1_Channel4->CCR |= DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE; // 8bit, mem++, mem->per, transcompl irq
+    // Tx CNDTR set @ each transmission due to data size
+    NVIC_SetPriority(DMA1_Channel4_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel4_IRQn);
+    NVIC_SetPriority(USART1_IRQn, 0);
+    // setup usart1
+    USART1->BRR = 72000000 / 115200;
+    USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; // 1start,8data,nstop; enable Rx,Tx,USART
+    while(!(USART1->SR & USART_SR_TC)){if(--tmout == 0) break;} // polling idle frame Transmission
+    USART1->SR = 0; // clear flags
+    USART1->CR1 |= USART_CR1_RXNEIE; // allow Rx IRQ
+    USART1->CR3 = USART_CR3_DMAT; // enable DMA Tx
+    NVIC_EnableIRQ(USART1_IRQn);
+}
+
+
+void usart1_isr(){
+    if(USART1->SR & USART_SR_RXNE){ // RX not emty - receive next char
+        uint8_t rb = USART1->DR;
+        if(idatalen[rbufno] < UARTBUFSZI){ // put next char into buf
+            rbuf[rbufno][idatalen[rbufno]++] = rb;
+            if(rb == '\n'){ // got newline - line ready
+                usart_linerdy = 1;
+                dlen = idatalen[rbufno];
+                recvdata = rbuf[rbufno];
+                // prepare other buffer
+                rbufno = !rbufno;
+                idatalen[rbufno] = 0;
+            }
+        }else{ // buffer overrun
+            usart_bufovr = 1;
+            idatalen[rbufno] = 0;
+        }
+    }
+}
+
+void dma1_channel4_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
+        DMA1->IFCR = DMA_IFCR_CTCIF4; // clear TC flag
+        usart_txrdy = 1;
+    }
+}