add USART snippet (Rx by USART interrupts, Tx by DMA; double buffering for both Tx/Rx)

F1-nolib/uart/README

@@ -1,5 +1,4 @@
-Toggle LEDs (PB8/PB9) on STM32F103 development board depending on buttons PC0,PC1:
-- no buttons pressed == 'SOS' in Morze @ LED D1
-- Button S2 pressed - D1 blinks with period of 5s
-- Button S1 pressed - D2 blinks with period of 1s
-
+Toggle LED PB9 on STM32F103 development board once per second
+Allow to turn on/off LED PB8 depending on user commands over USART (0/1) and check its state (s)
+Show information in USART console about S2/S3 buttons pressed
+USART: 115200 8n1

F1-nolib/uart/main.c

@@ -22,6 +22,9 @@
 #include "stm32f1.h"
 #include "usart.h"
 
+// debounce pause (ms - 1)
+#define DEBOUNCE_PAUSE      (9)
+
 static volatile uint32_t Tms = 0; // milliseconds from last reset
 
 // Called when systick fires
@@ -40,6 +43,47 @@ static void gpio_setup(void){
     GPIOC->CRL = CRL(0, CNF_PUDINPUT|MODE_INPUT) | CRL(1, CNF_PUDINPUT|MODE_INPUT);
 }
 
+typedef enum{
+     BTN_PRESSED
+    ,BTN_RELEASED
+    ,BTN_DEBOUNCE
+    ,BTN_RELAX
+} button_state;
+
+button_state check_state(uint8_t N){
+    static uint32_t tlast[2] = {0,0};
+    static button_state oldstate[2] = {BTN_RELEASED, BTN_RELEASED};
+    button_state s = BTN_RELAX;
+    uint8_t b = pin_read(GPIOC, N+1); // == 1 if button released
+    if(b){ 
+        switch(oldstate[N]){
+            case BTN_PRESSED: // debounce pause for DEBOUNCE_PAUSE ms
+                s = oldstate[N] = BTN_DEBOUNCE;
+                tlast[N] = Tms;
+            break;
+            case BTN_DEBOUNCE: // check debounce pause
+                if(Tms - tlast[N] > DEBOUNCE_PAUSE){
+                    s = oldstate[N] = BTN_RELEASED;
+                }
+            break;
+            default: // BTN_RELEASED - do nothing -> return BTN_RELAX
+                ;
+        }
+    }else{
+        switch(oldstate[N]){
+            case BTN_RELEASED: 
+                s = BTN_PRESSED; // button was just pressed
+                __attribute__((fallthrough)); // change oldstate too
+            case BTN_DEBOUNCE: // change old state to BTN_PRESSED again
+                oldstate[N] = BTN_PRESSED; // returned state still relax
+            break;
+            default: // BTN_PRESSED before - do nothing
+                ;
+        }
+    }
+    return s;
+}
+
 int main(){
     int L;
     char *txt;
@@ -98,6 +142,26 @@ int main(){
             transmit_tbuf();
             L = 0;
         }
+        for(int i = 0; i < 2; ++i){
+            const char *st = NULL; 
+            switch(check_state(i)){
+                case BTN_PRESSED:
+                    st = "pressed";
+                break;
+                case BTN_RELEASED:
+                    st = "released";
+                break;
+                default:
+                    ; // nothing 
+            }
+            if(st){
+                SEND("The button");
+                usart_putchar('2' + i);
+                SEND(" was ");
+                SEND(st);
+                newline();
+            }
+        }
 
         /*
         uint8_t 

F1-nolib/uart/usart.c

@@ -53,32 +53,15 @@ int usart_getline(char **line){
 // transmit current tbuf and swap buffers
 void transmit_tbuf(){
     uint32_t tmout = 16000000;
-    while(!txrdy){if(--tmout == 0) break;}; // wait for previos buffer transmission
+    while(!txrdy){if(--tmout == 0) return;}; // wait for previos buffer transmission
     register int l = odatalen[tbufno];
     if(!l) return;
-//txrdy = 0;
+    txrdy = 0;
     odatalen[tbufno] = 0;
-    char *buf = tbuf[tbufno];
-    for(int i = 0; i < l; ++i){
-        USART1->DR = *buf++;
-        tmout = 16000000;
-        while(!(USART1->SR & USART_SR_TXE)){if(--tmout == 0)break;};
-    }
-    /*
-#if USARTNUM == 2
     DMA1_Channel4->CCR &= ~DMA_CCR_EN;
     DMA1_Channel4->CMAR = (uint32_t) tbuf[tbufno]; // mem
     DMA1_Channel4->CNDTR = l;
-    DMA1_Channel4->CCR |= DMA_CCR_EN; // start transmission
-#elif USARTNUM == 1
-    DMA1_Channel2->CCR &= ~DMA_CCR_EN;
-    DMA1_Channel2->CMAR = (uint32_t) tbuf[tbufno]; // mem
-    DMA1_Channel2->CNDTR = l;
-    DMA1_Channel2->CCR |= DMA_CCR_EN;
-#else
-#error "Not implemented"
-#endif
-*/
+    DMA1_Channel4->CCR |= DMA_CCR_EN;
     tbufno = !tbufno;
 }
 
@@ -113,16 +96,15 @@ 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 - Channel2 (default value in SYSCFG_CFGR1)
-    DMA1_Channel2->CPAR = (uint32_t) &USART1->TDR; // periph
-    DMA1_Channel2->CMAR = (uint32_t) tbuf; // mem
-    DMA1_Channel2->CCR |= DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE; // 8bit, mem++, mem->per, transcompl irq
+
+    // 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_Channel2_3_IRQn, 3);
-    NVIC_EnableIRQ(DMA1_Channel2_3_IRQn);*/
-    //USART1->CR3 = USART_CR3_DMAT; // enable DMA Tx
+    NVIC_SetPriority(DMA1_Channel4_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel4_IRQn);
     NVIC_SetPriority(USART1_IRQn, 0);
     // setup usart1
     USART1->BRR = 72000000 / 115200;
@@ -130,6 +112,7 @@ void usart_setup(){
     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);
 }
 
@@ -220,6 +203,14 @@ void hexdump(uint8_t *arr, uint16_t len){
         else if(l & 1) usart_putchar(' ');
     }
 }
+
+void dma1_channel4_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
+        DMA1->IFCR = DMA_IFCR_CTCIF4; // clear TC flag
+        txrdy = 1;
+    }
+}
+
 /*
 #if USARTNUM == 2
 void dma1_channel4_5_isr(){

F1-nolib/uart/usart.h

@@ -24,8 +24,8 @@
 #define __USART_H__
 
 // input and output buffers size
-#define UARTBUFSZI  (32)
-#define UARTBUFSZO  (512)
+#define UARTBUFSZI  (16)
+#define UARTBUFSZO  (32)
 // timeout between data bytes
 #ifndef TIMEOUT_MS
 #define TIMEOUT_MS (1500)