add SSI->SPI on NUCLEO042

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

@@ -0,0 +1,153 @@
+/*
+ * usart.c
+ *
+ * Copyright 2017 Edward V. Emelianoff <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 <stm32f0.h>
+#include <string.h>
+
+#include "usart.h"
+
+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
+;
+
+
+int rbufno = 0; // current rbuf number
+static char rbuf[UARTBUFSZ][2], tbuf[UARTBUFSZ]; // receive & transmit buffers
+static char *recvdata = NULL;
+
+/**
+ * return length of received data (without trailing zero
+ */
+int usart2_getline(char **line){
+    if(bufovr){
+        bufovr = 0;
+        linerdy = 0;
+        return 0;
+    }
+    *line = recvdata;
+    linerdy = 0;
+    return dlen;
+}
+
+TXstatus usart2_send(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    if(len > UARTBUFSZ) return STR_TOO_LONG;
+    txrdy = 0;
+    memcpy(tbuf, str, len);
+    DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel4->CNDTR = len;
+    DMA1_Channel4->CCR |= DMA_CCR_EN; // start transmission
+    return ALL_OK;
+}
+
+TXstatus usart2_send_blocking(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    int i;
+    bufovr = 0;
+    for(i = 0; i < len; ++i){
+        USART2->TDR = *str++;
+        while(!(USART2->ISR & USART_ISR_TXE));
+    }
+    txrdy = 1;
+    return ALL_OK;
+}
+
+
+// Nucleo's USART2 connected to VCP proxy of st-link
+void usart2_setup(){
+    // setup pins: PA2 (Tx - AF1), PA15 (Rx - AF1)
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_DMAEN;
+    // AF mode (AF1)
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER2|GPIO_MODER_MODER15))\
+                | (GPIO_MODER_MODER2_1 | GPIO_MODER_MODER15_1);
+    GPIOA->AFR[0] = (GPIOA->AFR[0] &~GPIO_AFRH_AFRH2) | 1 << (2 * 4); // PA2
+    GPIOA->AFR[1] = (GPIOA->AFR[1] &~GPIO_AFRH_AFRH7) | 1 << (7 * 4); // PA15
+    // DMA: Tx - Ch4
+    DMA1_Channel4->CPAR = (uint32_t) &USART2->TDR; // periph
+    DMA1_Channel4->CMAR = (uint32_t) tbuf; // mem
+    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_5_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel4_5_IRQn);
+    NVIC_SetPriority(USART2_IRQn, 0);
+    // setup usart2
+    RCC->APB1ENR |= RCC_APB1ENR_USART2EN; // clock
+    // oversampling by16, 115200bps (fck=48mHz)
+    //USART2_BRR = 0x1a1; // 48000000 / 115200
+    USART2->BRR = 480000 / 1152;
+    USART2->CR3 = USART_CR3_DMAT; // enable DMA Tx
+    USART2->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; // 1start,8data,nstop; enable Rx,Tx,USART
+    while(!(USART2->ISR & USART_ISR_TC)); // polling idle frame Transmission
+    USART2->ICR |= USART_ICR_TCCF; // clear TC flag
+    USART2->CR1 |= USART_CR1_RXNEIE;
+    NVIC_EnableIRQ(USART2_IRQn);
+}
+
+
+void dma1_channel4_5_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
+        DMA1->IFCR |= DMA_IFCR_CTCIF4; // clear TC flag
+        txrdy = 1;
+    }
+}
+
+void usart2_isr(){
+    #ifdef CHECK_TMOUT
+    static uint32_t tmout = 0;
+    #endif
+    if(USART2->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 = USART2->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
+        }
+    }
+}