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  2. /*
  3. Title: SerialCom.c
  4. Date Created: 6/9/2009
  5. Last Modified: 6/9/2009
  6. Target: Atmel ATmega168
  7. Environment: AVR-GCC
  9. Note: the makefile is expecting a '168 with a 16 MHz crystal.
  11. Adapted from the Arduino sketch "Serial Call and Response," by Tom Igoe.
  13. // This program sends an ASCII A (byte of value 65) on startup
  14. // and repeats that until it gets some data in.
  15. // Then it waits for a byte in the serial port, and
  16. // sends three (faked) sensor values whenever it gets a byte in.
  20. Written by Windell Oskay, http://www.evilmadscientist.com/
  22. Copyright 2009 Windell H. Oskay
  23. Distributed under the terms of the GNU General Public License, please see below.
  25. Additional license terms may be available; please contact us for more information.
  29. More information about this project is at
  30. http://www.evilmadscientist.com/article.php/peggy
  31. */
  36. #include <avr/io.h>
  37. //#include <avr/interrupt.h>
  39. #define F_CPU 16000000 // 16 MHz oscillator.
  40. #define BaudRate 9600
  41. #define MYUBRR (F_CPU / 16 / BaudRate ) - 1
  47. void delayLong()
  48. {
  49. unsigned int delayvar;
  50. delayvar = 0;
  51. while (delayvar <= 65500U)
  52. {
  53. asm("nop");
  54. delayvar++;
  55. }
  56. }
  59. unsigned char serialCheckRxComplete(void)
  60. {
  61. return( UCSR0A & _BV(RXC0)) ; // nonzero if serial data is available to read.
  62. }
  64. unsigned char serialCheckTxReady(void)
  65. {
  66. return( UCSR0A & _BV(UDRE0) ) ; // nonzero if transmit register is ready to receive new data.
  67. }
  69. unsigned char serialRead(void)
  70. {
  71. while (serialCheckRxComplete() == 0) // While data is NOT available to read
  72. {;;}
  73. return UDR0;
  74. }
  76. void serialWrite(unsigned char DataOut)
  77. {
  78. while (serialCheckTxReady() == 0) // while NOT ready to transmit
  79. {;;}
  80. UDR0 = DataOut;
  81. }
  85. void establishContact() {
  86. while (serialCheckRxComplete() == 0) {
  87. serialWrite('H');
  88. // serialWrite(65U);
  89. delayLong();
  90. delayLong();
  91. delayLong();
  92. delayLong();
  93. delayLong();
  94. delayLong();
  95. delayLong();
  96. }
  97. }
  101. int main (void)
  102. {
  104. //Interrupts are not needed in this program. You can optionally disable interrupts.
  105. //asm("cli"); // DISABLE global interrupts.
  108. DDRD = _BV(1);
  109. DDRB = _BV(0) | _BV(1) | _BV(3) | _BV(5);
  111. //Serial Initialization
  113. /*Set baud rate */
  114. UBRR0H = (unsigned char)(MYUBRR>>8);
  115. UBRR0L = (unsigned char) MYUBRR;
  116. /* Enable receiver and transmitter */
  117. UCSR0B = (1<<RXEN0)|(1<<TXEN0);
  118. /* Frame format: 8data, No parity, 1stop bit */
  119. UCSR0C = (3<<UCSZ00);
  122. int firstSensor = 0; // first analog sensor
  123. int secondSensor = 0; // second analog sensor
  124. int thirdSensor = 0; // digital sensor
  125. int inByte = 0; // incoming serial byte
  128. PORTB |= _BV(1); // Turn on LED @ PB1
  131. establishContact(); // send a byte to establish contact until Processing responds
  133. PORTB &= 253U; // Turn off LED
  136. for (;;) // main loop
  137. {
  140. if (serialCheckRxComplete()) {
  141. PORTB |= _BV(1); // Turn on LED @ PB1
  143. inByte = serialRead();
  145. // Simulated data!
  146. firstSensor++;
  148. secondSensor = firstSensor * firstSensor;
  150. thirdSensor = firstSensor + secondSensor;
  152. serialWrite(firstSensor & 255U);
  153. serialWrite(secondSensor & 255U);
  154. serialWrite(thirdSensor & 255U);
  155. //serialWrite(inByte);
  157. PORTB &= 253U; // Turn off LED
  159. }
  165. } //End main loop.
  166. return 0;
  167. }
  168.  
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