initial commit, compiles for ATTINY84 with TX on PA5 and RX on PA6

2020-02-21 20:48:19 +01:00
commit 95ccf534a4
7 changed files with 400 additions and 0 deletions
--- a/suart.c
+++ b/suart.c
@@ -0,0 +1,209 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#ifndef SIGNAL
+#include <avr/signal.h>
+#endif // SIGNAL 
+
+#include "suart.h"
+
+// Folgende Zeile einkommentieren, falls FIFO verwendet werden soll 
+#include "fifo.h" 
+
+#define F_CPU 1000000
+#define BAUDRATE 38400
+
+#define nop() __asm volatile ("nop")
+
+#ifdef SUART_TXD
+    #define SUART_TXD_PORT PORTA
+    #define SUART_TXD_DDR  DDRA
+    #define SUART_TXD_BIT  PA5
+    static volatile uint16_t outframe;
+#endif // SUART_TXD 
+
+#ifdef SUART_RXD
+    #define SUART_RXD_PORT PORTA
+    #define SUART_RXD_PIN  PINA
+    #define SUART_RXD_DDR  DDRA
+    #define SUART_RXD_BIT  PA6
+    static volatile uint16_t inframe;
+    static volatile uint8_t inbits, received;
+
+    #ifdef _FIFO_H_
+        #define INBUF_SIZE 4
+        static uint8_t inbuf[INBUF_SIZE];
+        fifo_t infifo;
+    #else // _FIFO_H_ 
+        static volatile uint8_t indata;
+    #endif // _FIFO_H_ 
+#endif // SUART_RXD
+
+// Initialisierung für einen ATmega8 
+// Für andere AVR-Derivate sieht dies vermutlich anders aus: 
+// Registernamen ändern sich (zB TIMSK0 anstatt TIMSK, etc). 
+void uart_init()
+{
+    uint8_t tifr = 0;
+    uint8_t sreg = SREG;
+    cli();
+
+    // Mode #4 für Timer1 
+    // und volle MCU clock 
+    // IC Noise Cancel 
+    // IC on Falling Edge 
+    TCCR1A = 0;
+    TCCR1B = (1 << WGM12) | (1 << CS10) | (0 << ICES1) | (1 << ICNC1);
+
+    // OutputCompare für gewünschte Timer1 Frequenz 
+    OCR1A = (uint16_t) ((uint32_t) F_CPU/BAUDRATE);
+
+#ifdef SUART_RXD
+    SUART_RXD_DDR  &= ~(1 << SUART_RXD_BIT);
+    SUART_RXD_PORT |=  (1 << SUART_RXD_BIT);
+    TIMSK0 |= (1 << ICIE1);
+    tifr  |= (1 << ICF1) | (1 << OCF1B);
+#else
+    TIMSK0 &= ~(1 << ICIE1);
+#endif // SUART_RXD 
+
+#ifdef SUART_TXD
+    tifr |= (1 << OCF1A);
+    SUART_TXD_PORT |= (1 << SUART_TXD_BIT);
+    SUART_TXD_DDR  |= (1 << SUART_TXD_BIT);
+    outframe = 0;
+#endif // SUART_TXD 
+
+    TIFR1 = tifr;
+
+    SREG = sreg;
+
+#ifdef _FIFO_H_
+   fifo_init (&infifo,   inbuf, INBUF_SIZE);
+#endif // _FIFO_H_
+
+}
+
+// TRANSMITTER
+#ifdef SUART_TXD
+void uart_putc (const char c)
+{
+    do
+    {
+        sei(); nop(); cli(); // yield(); 
+    } while (outframe);
+
+    // frame = *.P.7.6.5.4.3.2.1.0.S   S=Start(0), P=Stop(1), *=Endemarke(1) 
+    outframe = (3 << 9) | (((uint8_t) c) << 1);
+
+    TIMSK0 |= (1 << OCIE1A);
+    TIFR1   = (1 << OCF1A);
+
+    sei();
+}
+#endif // SUART_TXD 
+#ifdef SUART_TXD
+SIGNAL (SIG_OUTPUT_COMPARE1A)
+{
+    uint16_t data = outframe;
+   
+    if (data & 1)      SUART_TXD_PORT |=  (1 << SUART_TXD_BIT);
+    else               SUART_TXD_PORT &= ~(1 << SUART_TXD_BIT);
+   
+    if (1 == data)
+    {
+        TIMSK0 &= ~(1 << OCIE1A);
+    }   
+   
+    outframe = data >> 1;
+}
+#endif // SUART_TXD
+
+// RECEIVER
+#ifdef SUART_RXD
+SIGNAL (SIG_INPUT_CAPTURE1)
+{
+    uint16_t icr1  = ICR1;
+    uint16_t ocr1a = OCR1A;
+   
+    // Eine halbe Bitzeit zu ICR1 addieren (modulo OCR1A) und nach OCR1B
+    uint16_t ocr1b = icr1 + ocr1a/2;
+    if (ocr1b >= ocr1a)
+        ocr1b -= ocr1a;
+    OCR1B = ocr1b;
+   
+    TIFR1 = (1 << OCF1B);
+    TIMSK0 = (TIMSK0 & ~(1 << ICIE1)) | (1 << OCIE1B);
+    inframe = 0;
+    inbits = 0;
+}
+#endif // SUART_RXD
+#ifdef SUART_RXD
+SIGNAL (SIG_OUTPUT_COMPARE1B)
+{
+    uint16_t data = inframe >> 1;
+   
+    if (SUART_RXD_PIN & (1 << SUART_RXD_BIT))
+        data |= (1 << 9);
+      
+    uint8_t bits = inbits+1;
+   
+    if (10 == bits)
+    {
+        if ((data & 1) == 0)
+            if (data >= (1 << 9))
+            {
+#ifdef _FIFO_H_         
+                _inline_fifo_put (&infifo, data >> 1);
+#else            
+                indata = data >> 1;
+#endif // _FIFO_H_            
+                received = 1;
+            }
+      
+        TIMSK0 = (TIMSK0 & ~(1 << OCIE1B)) | (1 << ICIE1);
+        TIFR1 = (1 << ICF1);
+    }
+    else
+    {
+        inbits = bits;
+        inframe = data;
+    }
+}
+#endif // SUART_RXD
+#ifdef SUART_RXD
+#ifdef _FIFO_H_
+
+int uart_getc_wait()
+{
+    return (int) fifo_get_wait (&infifo);
+}
+
+int uart_getc_nowait()
+{
+    return fifo_get_nowait (&infifo);
+}
+
+#else // _FIFO_H_
+
+int uart_getc_wait()
+{
+    while (!received)   {}
+    received = 0;
+   
+    return (int) indata;
+}
+
+int uart_getc_nowait()
+{
+    if (received)
+    {
+        received = 0;
+        return (int) indata;
+    }
+   
+    return -1;
+}
+
+#endif // _FIFO_H_
+#endif // SUART_RXD