test USART with ringbuffer - OK; TODO: rewrite all proto for usage USB & USART

F3:F303/MLX90640-allsky/usart.c

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+/*
+ * This file is part of the ir-allsky project.
+ * Copyright 2025 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 <stm32f3.h>
+#include <string.h>
+
+#include "hardware.h"
+#include "ringbuffer.h"
+#include "usart.h"
+
+// unlike USB where you can hold NACK until user process frees ringbuffer, here we can't do that
+// so USART writing forced by user (ringbuffer full or timeout by `usart_chk`)
+
+extern volatile uint32_t Tms;
+// flags
+static volatile uint8_t bufovr = 0, // input buffer overfull
+                        rbufno = 0, // index of active receiving buffer
+                        txrdy  = 1; // transmission done
+
+static char rbuf[2][UARTBUFSZI]; // double receiving buffer
+static char *recvdata = NULL; // pointer to last received data
+static volatile int recvdatalen = 0;
+// to transmit images we reserve circular buffer large enough to hold full image
+static uint8_t rbdata[DMARBSZ];
+static ringbuffer dmarb = {.data = rbdata, .length = DMARBSZ, .head = 0, .tail = 0};
+
+static int transmit_tbuf();
+
+// return 1 if overflow was
+int usart_ovr(){
+    if(bufovr){
+        bufovr = 0;
+        return 1;
+    }
+    return 0;
+}
+
+// check if the buffer was filled >TRANSMIT_DELAY ago (transmit it then)
+void usart_process(){
+    transmit_tbuf();
+}
+
+/**
+ * @brief usart_getline - read one dataportion
+ * @param buf - user buffer
+ * @param len - its length
+ * @return amount of bytes
+ */
+char *usart_getline(int *len){
+    if(!recvdatalen) return NULL;
+    if(len) *len = recvdatalen;
+    recvdatalen = 0;
+    return recvdata;
+}
+
+// transmit next dataportion from ringbuffer
+static int transmit_tbuf(){
+    static uint8_t tbuf[UARTBUFSZO];
+    uint32_t T0 = Tms;
+    while(!txrdy && Tms - T0 < RXRDY_TMOUT) IWDG->KR = IWDG_REFRESH;
+    if(!txrdy) return 0;
+    int l = RB_read(&dmarb, tbuf, UARTBUFSZO);
+    if(l < 1) return 1;
+    txrdy = 0;
+    DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel4->CMAR = (uint32_t) tbuf;
+    DMA1_Channel4->CNDTR = l;
+    DMA1_Channel4->CCR |= DMA_CCR_EN;
+    return 1;
+}
+
+// return 0 if can't write to ringbuffer
+int usart_putchar(const char ch){
+    int r = RB_write(&dmarb, (uint8_t*)&ch, 1);
+    if(r != 1){
+        if(transmit_tbuf()) r = RB_write(&dmarb, (uint8_t*)&ch, 1);
+    }
+    return r;
+}
+
+// @return amount of written bytes
+int usart_send(const uint8_t *data, int len){
+    if(len > DMARBSZ) return FALSE;
+    int L = 0;
+    do{
+        int r = RB_write(&dmarb, data, len - L);
+        if(r < 1){
+            if(!transmit_tbuf()) return L;
+            else continue;
+        }
+        L += r;
+        data += r;
+    }while(L < len);
+    return L;
+}
+
+// WARNING! strlen of `str` should be less than RBout size!
+// @return amount of written bytes
+int usart_sendstr(const char *str){
+    return usart_send((uint8_t*)str, strlen(str));
+}
+
+// USART1: Rx - PA10 (AF7), Tx - PA9  (AF7)
+int usart_setup(uint32_t speed){
+    if(speed < 200 || speed > 3000000) return FALSE;
+    // setup pins:
+    GPIOA->MODER = (GPIOA->MODER & (MODER_CLR(9) & MODER_CLR(10))) |
+                    MODER_AF(9) | MODER_AF(10);
+    GPIOA->AFR[1] = (GPIOA->AFR[1] & ~(GPIO_AFRH_AFRH1 | GPIO_AFRH_AFRH2)) |
+                    AFRf(7, 9) | AFRf(7, 10);
+    // clock
+    RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
+    RCC->AHBENR |= RCC_AHBENR_DMA1EN;
+    USART1->ICR = 0xffffffff; // clear all flags
+    // Tx DMA
+    DMA1_Channel4->CCR = 0;
+    DMA1_Channel4->CPAR = (uint32_t) &USART1->TDR; // periph
+    DMA1_Channel4->CCR |= DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE; // 8bit, mem++, mem->per, transcompl irq
+    // Rx DMA
+    DMA1_Channel5->CCR = 0;
+    DMA1_Channel5->CPAR = (uint32_t) &USART1->RDR; // periph
+    DMA1_Channel5->CMAR = (uint32_t) rbuf[0];
+    DMA1_Channel5->CNDTR = UARTBUFSZI;
+    DMA1_Channel5->CCR |= DMA_CCR_MINC | DMA_CCR_TCIE | DMA_CCR_EN; // 8bit, mem++, per->mem, transcompl irq, enable
+    // setup usart
+    USART1->BRR = SysFreq / speed;
+    USART1->CR3 = USART_CR3_DMAT | USART_CR3_DMAR; // enable DMA Tx/Rx
+    USART1->CR2 = USART_CR2_ADD_VAL('\n'); // init character match register: our input proto is string-based
+    USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE | USART_CR1_CMIE; // 1start,8data,nstop; enable Rx,Tx,USART; enable CharacterMatch Irq
+    uint32_t tmout = 16000000;
+    while(!(USART1->ISR & USART_ISR_TC)){if(--tmout == 0) break;} // polling idle frame Transmission
+    USART1->ICR = 0xffffffff; // clear all flags again
+    NVIC_EnableIRQ(USART1_IRQn);
+    NVIC_EnableIRQ(DMA1_Channel4_IRQn);
+    NVIC_EnableIRQ(DMA1_Channel5_IRQn);
+    NVIC_SetPriority(DMA1_Channel5_IRQn, 0);
+    NVIC_SetPriority(USART1_IRQn, 4); // set character match priority lower
+    return TRUE;
+}
+
+void usart_stop(){
+    RCC->APB2ENR &= ~RCC_APB2ENR_USART1EN;
+}
+
+// USART1 character match interrupt
+void usart1_exti25_isr(){
+    DMA1_Channel5->CCR &= ~DMA_CCR_EN; // temporaly disable DMA
+    USART1->ICR = USART_ICR_CMCF; // clear character match flag
+    register int l = UARTBUFSZI - DMA1_Channel5->CNDTR - 1; // substitute '\n' with '\0', omit empty strings!
+    if(l > 0){
+        if(recvdata){ // user didn't read old data - mark as buffer overflow
+            bufovr = 1;
+        }
+        recvdata = rbuf[rbufno];
+        recvdata[l] = 0;
+        rbufno = !rbufno;
+        recvdatalen = l;
+    }
+    DMA1_Channel5->CMAR = (uint32_t) rbuf[rbufno];
+    DMA1_Channel5->CNDTR = UARTBUFSZI;
+    DMA1_Channel5->CCR |= DMA_CCR_EN;
+}
+
+// USART1 Tx complete
+void dma1_channel4_isr(){
+    DMA1->IFCR |= DMA_IFCR_CTCIF4;
+    txrdy = 1;
+}
+
+// USART1 Rx buffer overrun
+void dma1_channel5_isr(){
+    DMA1_Channel5->CCR &= ~DMA_CCR_EN;
+    DMA1->IFCR |= DMA_IFCR_CTCIF5;
+    DMA1_Channel5->CMAR = (uint32_t) rbuf[rbufno];
+    DMA1_Channel5->CNDTR = UARTBUFSZI;
+    bufovr = 1;
+    DMA1_Channel5->CCR |= DMA_CCR_EN;
+}