- UART takes baudrate on init

- UART calculate optimized baud prescaler

git-svn-id: http://moon:8086/svn/projects/HendiControl@47 fda53097-d464-4ada-af97-ba876c37ca34

Control/firmware/uart_echo/main.c

@@ -13,6 +13,7 @@
 #include <avr/wdt.h>
 #include <avr/interrupt.h>
 
+#include "machine.h"
 #include "fifo.h"
 #include "message.h"
 #include "adc.h"
@@ -23,16 +24,8 @@
 #include "mcp42x6.h"
 
 #define PRINT(a,...)	printf(a, ##__VA_ARGS__)
-#define ARDUINO_NANO			1
-
 #define PRINT_PROMPT	putchar(0x0D);putchar(0x0A);putchar(':');
-#if ARDUINO_NANO
+#define USART_BAUDRATE	115200UL
-#define F_CPU			(16000000UL)	// MHz
-#else
-#define F_CPU			(18432000UL)	// MHz
-#endif
-#define USART_BAUDRATE	9600UL
-#define BAUD_PRESCALE	(((F_CPU / (USART_BAUDRATE * 16UL))) - 1)
 #define TIMER_HW_CLOCK	(F_CPU/8)
 #define TIMER_IRQ_CLOCK	1000UL
 #define TIMER_HW_RELOAD	(0xFFFF-(TIMER_HW_CLOCK/TIMER_IRQ_CLOCK))
@@ -96,7 +89,7 @@ int main(void)
 	fifo_init(&messageFifo, 8, sizeof(Msg_t), "Fifo");
 	
     /* Replace with your application code */
-	uart_init(&messageFifo, BAUD_PRESCALE);
+	uart_init(&messageFifo, USART_BAUDRATE);
 	timer_init(&messageFifo, TIMER_HW_RELOAD, TimerClockSel_PS_8);
 	adc_init(&messageFifo);
 	i2c_init();

Control/firmware/uart_echo/uart.c

@@ -33,13 +33,31 @@ ISR(USART_RX_vect)
 	}
 }
 
-void uart_init(Fifo *pFifo, uint16_t BAUD_PRESCALE)
+void uart_init(Fifo *pFifo, uint32_t baudrate)
 {
 	g_pFifo = pFifo;
 
+	uint16_t prescale8 = UART_PRESCALE(baudrate, 8UL);
+	uint16_t prescale16 = UART_PRESCALE(baudrate, 16UL);
+	
+	uint32_t baud8 = ((prescale8+1) * 8);
+	uint32_t baud16 = ((prescale16+1) * 16);
+	
+	uint32_t err8 = abs(baudrate - baud8);
+	uint32_t err16 = abs(baudrate - baud16);
+	
+	uint16_t prescale = prescale16;
+	if (err8 < err16)
+	{
+		prescale = prescale8;
+		
+		// Double UART speed
+		UCSR0A |= 1 << U2X0;
+	}
+	
 	// Set baud rate
-	UBRR0L  = (uint8_t)BAUD_PRESCALE;
+	UBRR0L  = (uint8_t)prescale;
-	UBRR0H = (uint8_t)(BAUD_PRESCALE >> 8);
+	UBRR0H = (uint8_t)(prescale >> 8);
 	
 	// Enable receiver and transmitter
 	UCSR0B = (1<<TXEN0)|(1<<RXEN0);

Control/firmware/uart_echo/uart.h

@@ -9,11 +9,15 @@
 #ifndef UART_H_
 #define UART_H_
 
+#include "machine.h"
 #include "fifo.h"
 
-void uart_init(Fifo *pFifo, uint16_t BAUD_PRESCALE);
+#define UART_PRESCALE(baudrate, smpPerBit) ((5+ 10*F_CPU / (baudrate*smpPerBit) - 1)/10)
+
+void uart_init(Fifo *pFifo, uint32_t baudrate);
 void uart_putc(char c);
 int uart_putchar(char c, FILE *stream);
 void uart_puts(char const *str);
 
+
 #endif /* UART_H_ */

Control/firmware/uart_echo/uart_echo.cproj

@@ -95,6 +95,7 @@
   <avrgcc.compiler.symbols.DefSymbols>
     <ListValues>
       <Value>NDEBUG</Value>
+      <Value>ARDUINO_NANO=1</Value>
     </ListValues>
   </avrgcc.compiler.symbols.DefSymbols>
   <avrgcc.compiler.directories.IncludePaths>
@@ -117,7 +118,7 @@
       <Value>%24(PackRepoDir)\atmel\ATmega_DFP\1.2.209\include</Value>
     </ListValues>
   </avrgcc.assembler.general.IncludePaths>
-      </AvrGcc>
+</AvrGcc>
     </ToolchainSettings>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)' == 'Debug' ">
@@ -134,6 +135,7 @@
   <avrgcc.compiler.symbols.DefSymbols>
     <ListValues>
       <Value>DEBUG</Value>
+      <Value>ARDUINO_NANO=1</Value>
     </ListValues>
   </avrgcc.compiler.symbols.DefSymbols>
   <avrgcc.compiler.directories.IncludePaths>
@@ -157,7 +159,7 @@
     </ListValues>
   </avrgcc.assembler.general.IncludePaths>
   <avrgcc.assembler.debugging.DebugLevel>Default (-Wa,-g)</avrgcc.assembler.debugging.DebugLevel>
-      </AvrGcc>
+</AvrGcc>
     </ToolchainSettings>
   </PropertyGroup>
   <ItemGroup>
@@ -179,6 +181,9 @@
     <Compile Include="i2c.h">
       <SubType>compile</SubType>
     </Compile>
+    <Compile Include="machine.h">
+      <SubType>compile</SubType>
+    </Compile>
     <Compile Include="main.c">
       <SubType>compile</SubType>
     </Compile>