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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. #define F_CPU 16000000 // 16 MHz oscillator.
  38. #define BaudRate 9600
  39. #define MYUBRR (F_CPU / 16 / BaudRate ) - 1
  45. void delayLong()
  46. {
  47. unsigned int delayvar;
  48. delayvar = 0;
  49. while (delayvar <= 65500U)
  50. {
  51. asm("nop");
  52. delayvar++;
  53. }
  54. }
  57. unsigned char serialCheckRxComplete(void)
  58. {
  59. return( UCSR0A & (1<<RXC0)) ; // nonzero if serial data is available to read.
  60. }
  62. unsigned char serialCheckTxReady(void)
  63. {
  64. return( UCSR0A & (1<<UDRE0) ) ; // nonzero if transmit register is ready to receive new data.
  65. }
  67. unsigned char serialRead(void)
  68. {
  69. while (serialCheckRxComplete() == 0) // While data is NOT available to read
  70. {;;}
  71. return UDR0;
  72. }
  74. void serialWrite(unsigned char DataOut)
  75. {
  76. while (serialCheckTxReady() == 0) // while NOT ready to transmit
  77. {;;}
  78. UDR0 = DataOut;
  79. }
  83. void establishContact() {
  84. while (serialCheckRxComplete() == 0) {
  85. serialWrite('H');
  86. // serialWrite(65U);
  87. delayLong();
  88. delayLong();
  89. delayLong();
  90. delayLong();
  91. delayLong();
  92. delayLong();
  93. delayLong();
  94. }
  95. }
  99. int main (void)
  100. {
  102. //Interrupts are not needed in this program. You can optionally disable interrupts.
  103. //asm("cli"); // DISABLE global interrupts.
  106. DDRD = (1<<1); // portd, pin 1 as output, TXD pin
  107. DDRB = (1<<0) | (1<<1) | (1<<3) | (1<<5);
  109. //Serial Initialization
  111. /*Set baud rate */
  112. UBRR0H = (unsigned char)(MYUBRR>>8);
  113. UBRR0L = (unsigned char) MYUBRR;
  114. /* Enable receiver and transmitter */
  115. UCSR0B = (1<<RXEN0)|(1<<TXEN0);
  116. /* Frame format: 8data, No parity, 1stop bit */
  117. //UCSR0C = (3<<UCSZ00); //== 00000110
  118. //UCRS0C |= (1<<1) | (1<<2); //these settings are also the chip default, so not needed
  120. int inByte = 0; // incoming serial byte
  123. PORTB |= (1<<1); // Turn on LED @ PB1
  126. establishContact(); // send a byte to establish contact until Processing responds
  128. PORTB &= 253U; // Turn off LED
  131. for (;;) {
  132. if (serialCheckRxComplete()) {
  133. PORTB |= (1<<1); // Turn on LED @ PB1
  135. inByte = serialRead();
  137. serialWrite(inByte);
  139. PORTB &= 253U; // Turn off LED
  141. }
  143. }
  144. return 0;
  145. }
  146.  
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