added links to README.md

README.md

@@ -28,3 +28,9 @@ libdeps_dir = depends
 In diesem Fall sollte man davon absehen, die automatisch vom PIO 
 heruntergeladenen Bibliotheken ins Git des eigenen Projektes einzuchecken.
 Es empfiehlt sich in dem Fall `depends` ins `.gitignore` einzufügen.
+
+## Interrrupts
+Die UART-Schnittstelle und TWI bzw. I²C arbeiten mit Interrupts. Bei der 
+Initialisierung der jeweiligen (oder auch beiden) Schnittstelle mit 
+[UART_Init()](src/uart.c) bzw. [TWI_Init()](src/twi.c) werden die Interrupts global aktiviert. 
+Die Schnittstellen sind nach der Initialisierung sofort funktionsfähig und können direkt verwendet werden. 

src/dataflash.c

@@ -1,11 +1,14 @@
 #include <avr/io.h>
 #include <stdint.h>
+#include <avr/interrupt.h>
 
 #include "spi.h"
 #include "dataflash.h"
 
-void
-dataflash_opcode_and_address (unsigned char opcode, unsigned int page, unsigned int offset)
+// Prevent Double Initialization
+unsigned short dataflash_flag = 0;
+
+void dataflash_opcode_and_address(unsigned char opcode, unsigned int page, unsigned int offset)
 {
   SPI_MasterTransfer(opcode);
   SPI_MasterTransfer((unsigned char)(page >> 7) & 0x1f);
@@ -13,29 +16,40 @@ dataflash_opcode_and_address (unsigned char opcode, unsigned int page, unsigned
   SPI_MasterTransfer((unsigned char)(offset));
 }
 
-void
-dataflash_wait (void)
+void dataflash_wait(void)
 {
   DATAFLASH_Chip_Select;
   SPI_MasterTransfer(DATAFLASH_STATUS_REGISTER_READ);
 
-  while (!(SPI_MasterTransferRead(0x00) & 0x80));
+  while (!(SPI_MasterTransferRead(0x00) & 0x80))
+    ;
 
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_init (void)
+void dataflash_init(void)
 {
+  // Check if already initialized
+  if (!(dataflash_flag & 1))
+  {
+    // Backup Status Register and disable Interrupts
+    uint8_t sreg = SREG;
+    cli();
     // AT45DB081 doesn't actually need an intialization,
     // only the ChipSelect should be configured as an output.
     DDRB |= (1 << PB4);
     DATAFLASH_Chip_Unselect;
     SPI_MasterInit();
+
+    // Restore Status Register
+    SREG = sreg;
+
+    // Set dataflash Init Flag
+    dataflash_flag = 1;
+  }
 }
 
-void
-dataflash_buffer_to_page (unsigned int page, unsigned char buffer)
+void dataflash_buffer_to_page(unsigned int page, unsigned char buffer)
 {
   dataflash_wait();
   DATAFLASH_Chip_Select;
@@ -43,22 +57,19 @@ dataflash_buffer_to_page (unsigned int page, unsigned char buffer)
   switch (buffer)
   {
   default:
-      dataflash_opcode_and_address
-        (DATAFLASH_BUFFER_1_TO_MAIN_MEMORY_PAGE_PROGRAM_WITH_BUILT_IN_ERASE,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_1_TO_MAIN_MEMORY_PAGE_PROGRAM_WITH_BUILT_IN_ERASE,
                                  page, 0x00);
     break;
 
   case 2:
-      dataflash_opcode_and_address
-        (DATAFLASH_BUFFER_2_TO_MAIN_MEMORY_PAGE_PROGRAM_WITH_BUILT_IN_ERASE,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_2_TO_MAIN_MEMORY_PAGE_PROGRAM_WITH_BUILT_IN_ERASE,
                                  page, 0x00);
     break;
   }
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_page_to_buffer (unsigned int page, unsigned char buffer)
+void dataflash_page_to_buffer(unsigned int page, unsigned char buffer)
 {
   dataflash_wait();
   DATAFLASH_Chip_Select;
@@ -66,22 +77,19 @@ dataflash_page_to_buffer (unsigned int page, unsigned char buffer)
   switch (buffer)
   {
   default:
-      dataflash_opcode_and_address 
-        (DATAFLASH_MAIN_MEMORY_PAGE_TO_BUFFER_1_TRANSFER,
+    dataflash_opcode_and_address(DATAFLASH_MAIN_MEMORY_PAGE_TO_BUFFER_1_TRANSFER,
                                  page, 0x00);
     break;
 
   case 2:
-      dataflash_opcode_and_address 
-        (DATAFLASH_MAIN_MEMORY_PAGE_TO_BUFFER_2_TRANSFER,
+    dataflash_opcode_and_address(DATAFLASH_MAIN_MEMORY_PAGE_TO_BUFFER_2_TRANSFER,
                                  page, 0x00);
     break;
   }
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_buffer_read (unsigned char buffer, unsigned int offset,
+void dataflash_buffer_read(unsigned char buffer, unsigned int offset,
                            unsigned int length, unsigned char *array)
 {
   dataflash_wait();
@@ -90,14 +98,12 @@ dataflash_buffer_read (unsigned char buffer, unsigned int offset,
   switch (buffer)
   {
   default:
-      dataflash_opcode_and_address 
-        (DATAFLASH_BUFFER_1_READ_LF,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_1_READ_LF,
                                  0x00, offset);
     break;
 
   case 2:
-      dataflash_opcode_and_address 
-        (DATAFLASH_BUFFER_2_READ_LF,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_2_READ_LF,
                                  0x00, offset);
     break;
   }
@@ -112,8 +118,7 @@ dataflash_buffer_read (unsigned char buffer, unsigned int offset,
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_buffer_write (unsigned char buffer, unsigned int offset,
+void dataflash_buffer_write(unsigned char buffer, unsigned int offset,
                             unsigned int length, unsigned char *array)
 {
   dataflash_wait();
@@ -122,14 +127,12 @@ dataflash_buffer_write (unsigned char buffer, unsigned int offset,
   switch (buffer)
   {
   default:
-      dataflash_opcode_and_address 
-        (DATAFLASH_BUFFER_1_WRITE,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_1_WRITE,
                                  0x00, offset);
     break;
 
   case 2:
-      dataflash_opcode_and_address 
-        (DATAFLASH_BUFFER_2_WRITE,
+    dataflash_opcode_and_address(DATAFLASH_BUFFER_2_WRITE,
                                  0x00, offset);
     break;
   }
@@ -144,8 +147,7 @@ dataflash_buffer_write (unsigned char buffer, unsigned int offset,
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_read (unsigned int page, unsigned int offset,
+void dataflash_read(unsigned int page, unsigned int offset,
                     unsigned int length, unsigned char *array)
 {
   dataflash_wait();
@@ -163,8 +165,7 @@ dataflash_read (unsigned int page, unsigned int offset,
   DATAFLASH_Chip_Unselect;
 }
 
-void
-dataflash_chip_erase (void)
+void dataflash_chip_erase(void)
 {
   dataflash_wait();
   DATAFLASH_Chip_Select;

src/fifo.c

@@ -5,14 +5,20 @@ static uint8_t _fifo_get (fifo_t* f);
 
 void fifo_init(fifo_t *f, uint8_t *buffer, const uint8_t size)
 {
+  // Backup Status Register and disable Interrupts
+  uint8_t sreg = SREG;
+  cli();
   f->count = 0;
   f->pread = f->pwrite = buffer;
   f->read2end = f->write2end = f->size = size;
+  // Restore Status Register
+  SREG = sreg;
 }
 
 uint8_t fifo_get_wait(fifo_t *f)
 {
-  while (!f->count);
+  while (!f->count)
+    ;
 
   return _fifo_get(f);
 }

src/lcd.c

@@ -15,25 +15,29 @@ uint8_t lcd_frameupdate = 0;
 uint8_t lcd_textx = 0;
 uint8_t lcd_texty = 0;
 
-void
-LCD_Send (uint8_t data)
+// Prevent Double Initialization
+unsigned short LCD_flag = 0;
+
+void LCD_Send(uint8_t data)
 {
   SPI_MasterTransfer(data);
 }
 
-void
-LCD_Init (void)
+void LCD_Init(void)
+{
+  // Check if already initialized
+  if (!(LCD_flag & 1))
   {
     SPI_MasterInit();
 
-  /* Set Register Select and Chip Select as Output */
+    // Set Register Select and Chip Select as Output
     DDRC |= (1 << PC7) | (1 << PC6);
 
-  /* Backup Status Register and disable Interrupts */
+    // Backup Status Register and disable Interrupts
     uint8_t sreg = SREG;
     cli();
 
-  /* Starting Init Command Sequence */
+    // Starting Init Command Sequence
     LCD_Command_Mode;
     LCD_Chip_Select;
 
@@ -52,7 +56,7 @@ LCD_Init (void)
 
     LCD_Clear();
 
-  /* Restore Status Register */
+    // Restore Status Register
     SREG = sreg;
 
     // Initialize TWI for Backlight Control
@@ -61,10 +65,12 @@ LCD_Init (void)
 
     // Initialize Dataflash
     dataflash_init();
+    // Set UART Init Flag
+    LCD_flag = 1;
+  }
 }
 
-void
-LCD_Clear (void)
+void LCD_Clear(void)
 {
   uint8_t x = 0, y = 0;
 
@@ -77,12 +83,11 @@ LCD_Clear (void)
   LCD_Update();
 }
 
-void
-LCD_Update (void)
+void LCD_Update(void)
 {
   int8_t page = 7;
 
-  /* Backup Status Register and disable Interrupts */
+  // Backup Status Register and disable Interrupts
   uint8_t sreg = SREG;
   cli();
 
@@ -104,17 +109,15 @@ LCD_Update (void)
 
       LCD_Chip_Unselect;
     }
-    }
-  while (page--);
+  } while (page--);
 
   lcd_frameupdate = 0;
 
-  /* Restore Status Register */
+  // Restore Status Register
   SREG = sreg;
 }
 
-void
-LCD_DrawPixel (uint8_t x, uint8_t y, uint8_t mode)
+void LCD_DrawPixel(uint8_t x, uint8_t y, uint8_t mode)
 {
   // Check if x and y are within display coordinates
   if ((x < 128) && (y < 64))
@@ -145,8 +148,7 @@ LCD_DrawPixel (uint8_t x, uint8_t y, uint8_t mode)
   }
 }
 
-void
-LCD_DrawLine (uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint8_t mode)
+void LCD_DrawLine(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint8_t mode)
 {
   // look here: http://de.wikipedia.org/wiki/Bresenham-Algorithmus
   int8_t dx = abs(x1 - x0);
@@ -179,8 +181,7 @@ LCD_DrawLine (uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1, uint8_t mode)
   }
 }
 
-void
-LCD_DrawCircle (uint8_t x0, uint8_t y0, uint8_t radius, uint8_t mode)
+void LCD_DrawCircle(uint8_t x0, uint8_t y0, uint8_t radius, uint8_t mode)
 {
   // look here: http://de.wikipedia.org/wiki/Bresenham-Algorithmus
   int8_t f = 1 - radius;
@@ -218,8 +219,7 @@ LCD_DrawCircle (uint8_t x0, uint8_t y0, uint8_t radius, uint8_t mode)
   }
 }
 
-void
-LCD_PutChar (const char c)
+void LCD_PutChar(const char c)
 {
   // basic support for cr und new line
   switch (c)
@@ -247,8 +247,7 @@ LCD_PutChar (const char c)
   }
 }
 
-void
-LCD_PutString (const char *s)
+void LCD_PutString(const char *s)
 {
   // no empty strings allowed!
   if (*s)
@@ -256,13 +255,11 @@ LCD_PutString (const char *s)
     do
     {
       LCD_PutChar(*s);
-        }
-      while (*(++s));
+    } while (*(++s));
   }
 }
 
-void
-LCD_PutString_P (PGM_P s)
+void LCD_PutString_P(PGM_P s)
 {
   while (1)
   {
@@ -276,15 +273,13 @@ LCD_PutString_P (PGM_P s)
   }
 }
 
-void
-LCD_GotoXY (uint8_t x, uint8_t y)
+void LCD_GotoXY(uint8_t x, uint8_t y)
 {
   lcd_textx = x;
   lcd_texty = y;
 }
 
-void
-LCD_WipeLine (unsigned char line)
+void LCD_WipeLine(unsigned char line)
 {
   unsigned char x;
 
@@ -294,8 +289,7 @@ LCD_WipeLine (unsigned char line)
   lcd_frameupdate |= (1 << line);
 }
 
-void
-Backlight_Off (void)
+void Backlight_Off(void)
 {
   TWI_Start();
   TWI_Address_RW(0xc4);
@@ -308,8 +302,7 @@ Backlight_Off (void)
   TWI_Stop();
 }
 
-void
-Backlight_LED (uint8_t led_selector)
+void Backlight_LED(uint8_t led_selector)
 {
   TWI_Start();
   TWI_Address_RW(0xc4);
@@ -318,8 +311,7 @@ Backlight_LED (uint8_t led_selector)
   TWI_Stop();
 }
 
-void
-Backlight_PWM (uint8_t pwm, uint8_t prescaler, uint8_t value)
+void Backlight_PWM(uint8_t pwm, uint8_t prescaler, uint8_t value)
 {
   TWI_Start();
   TWI_Address_RW(0xc4);
@@ -334,8 +326,7 @@ Backlight_PWM (uint8_t pwm, uint8_t prescaler, uint8_t value)
   TWI_Stop();
 }
 
-void
-LCD_SavePage (unsigned int page)
+void LCD_SavePage(unsigned int page)
 {
   // transfer framebuffer to dataflash using buffer 2
   unsigned char line = 0;
@@ -347,8 +338,7 @@ LCD_SavePage (unsigned int page)
   }
 }
 
-void
-LCD_LoadPage (unsigned int page)
+void LCD_LoadPage(unsigned int page)
 {
   // transfer dataflash page to framebuffer
   unsigned char line = 0;

src/spi.c

@@ -1,50 +1,58 @@
 #include <avr/io.h>
 #include <stdint.h>
+#include <avr/interrupt.h>
 
 #include "spi.h"
 
 // Prevent Double Initialization
 unsigned short SPI_flag = 0;
 
-void
-SPI_MasterInit (void)
+void SPI_MasterInit(void)
 {
-  /* Check if already initialized */
+  // Check if already initialized
   if (!(SPI_flag & 1))
   {
-      /* Set MOSI and SCK output */
-      DDRB |= (1<<PB5)|(1<<PB7);
+    // Backup Status Register and disable Interrupts
+    uint8_t sreg = SREG;
+    cli();
 
-      /* Enable SPI, Master */
+    // Set MOSI, SCK and SS output
+    DDRB |= (1 << PB5) | (1 << PB7) | (1 << PB4);
+
+    // Enable SPI, Master
     SPCR = (1 << SPE) | (1 << MSTR);
 
-      /* Set Double SPI Speed Bit, SPI clock will be fck/2 */
+    // Set Double SPI Speed Bit, SPI clock will be fck/2
     SPSR = (1 << SPI2X);
 
-      /* Set SPI Init Flag */
+    // Restore Status Register
+    SREG = sreg;
+
+    // Set SPI Init Flag
     SPI_flag = 1;
   }
 }
 
-void
-SPI_MasterTransfer (unsigned char c)
+void SPI_MasterTransfer(unsigned char c)
 {
-  /* Start transmission */
+  // Start transmission
   SPDR = c;
 
-  /* Wait for transmission complete */
-  while (!(SPSR & (1<<SPIF)));
+  // Wait for transmission complete
+  while (!(SPSR & (1 << SPIF)))
+    ;
 }
 
 unsigned char
 SPI_MasterTransferRead(unsigned char c)
 {
-  /* Start transmission */
+  // Start transmission
   SPDR = c;
 
-  /* Wait for transmission complete */
-  while (!(SPSR & (1<<SPIF)));
+  // Wait for transmission complete
+  while (!(SPSR & (1 << SPIF)))
+    ;
 
-  /* Return incoming character */
+  // Return incoming character
   return SPDR;
 }

src/twi.c

@@ -6,9 +6,17 @@
 
 volatile uint8_t twi_timeout = 0x00;
 
-void
-TWI_Init (void)
+// Prevent Double Initialization
+unsigned short TWI_flag = 0;
+
+void TWI_Init(void)
 {
+  // Check if already initialized
+  if (!(TWI_flag & 1))
+  {
+    //disable global interrupts
+    cli();
+
     // Port Setup
     DDRC &= ~((1 << PC0) | (1 << PC1));
     PORTC |= (1 << PC0) | (1 << PC1);
@@ -22,9 +30,13 @@ TWI_Init (void)
 
     OCR2A = 125;
 
+    // Set TWI Init Flag
+    TWI_flag = 1;
+
     // Interrupts REQUIRED!
     sei();
   }
+}
 
 int16_t
 TWI_Start(void)
@@ -32,7 +44,8 @@ TWI_Start (void)
   twi_timeout = 10;
 
   TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
-  while ((twi_timeout) && (!(TWCR & (1 << TWINT))));
+  while ((twi_timeout) && (!(TWCR & (1 << TWINT))))
+    ;
 
   if (twi_timeout)
     return (int16_t)(TWSR & 0xf8);
@@ -47,7 +60,8 @@ TWI_Address_RW (uint8_t address)
 
   TWDR = address;
   TWCR = (1 << TWINT) | (1 << TWEN);
-  while ((twi_timeout) && (!(TWCR & (1 << TWINT))));
+  while ((twi_timeout) && (!(TWCR & (1 << TWINT))))
+    ;
 
   if (twi_timeout)
     return (int16_t)(TWSR & 0xf8);
@@ -62,7 +76,8 @@ TWI_Write (uint8_t data)
 
   TWDR = data;
   TWCR = (1 << TWINT) | (1 << TWEN);
-  while ((twi_timeout) && (!(TWCR & (1 << TWINT))));
+  while ((twi_timeout) && (!(TWCR & (1 << TWINT))))
+    ;
 
   if (twi_timeout)
     return (int16_t)(TWSR & 0xf8);
@@ -70,8 +85,7 @@ TWI_Write (uint8_t data)
     return -1;
 }
 
-void
-TWI_Stop (void)
+void TWI_Stop(void)
 {
   twi_timeout = 10;
 

src/uart.c

@@ -16,11 +16,16 @@ uint8_t uart_outbuf[UART_BUFSIZE_OUT];
 fifo_t uart_infifo;
 fifo_t uart_outfifo;
 
+// Prevent Double Initialization
+unsigned short UART_flag = 0;
+
 void
 UART_Init (void)
 {
-  // Save Status Register and disable Interrupts
-  uint8_t sreg = SREG;
+  // Check if already initialized
+  if (!(UART_flag & 1))
+  {
+  //disable Interrupts
   cli();
   
   // Set Baudrate according to datasheet (16MHz -> 9600 Baud -> 103)
@@ -32,12 +37,16 @@ UART_Init (void)
   // Reset Complete-Flags
   UCSR0A = (1 << RXC0)|(1 << TXC0);
   
-  // Reset Status Register
-  SREG = sreg;
+  // Interrupts REQUIRED!
+  sei();
   
   // Initialize FIFO Buffers
   fifo_init(&uart_infifo, uart_inbuf, UART_BUFSIZE_IN);
   fifo_init(&uart_outfifo, uart_outbuf, UART_BUFSIZE_OUT);
+
+  // Set UART Init Flag
+  UART_flag = 1;
+  }
 }
 
 int8_t