AVR Lesson: Output Pins I - Revision history

ITechGeek: Undo revision 4136 by Yrewevaca (talk)

2010-11-24T08:25:07Z

Undo revision 4136 by Yrewevaca (talk)

← Older revision		Revision as of 08:25, 24 November 2010
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	Part of the [[AVR Tutorial]]		Part of the [[AVR Tutorial]]

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	== The Code ==		== The Code ==
	~~<~~pre>~~<~~nowiki>		<pre><nowiki>

	/* Blinker Demo */		/* Blinker Demo */

	#include ~~<~~avr/io.h> /* Defines pins, ports, etc */		#include <avr/io.h> /* Defines pins, ports, etc */
	#define F_CPU 1000000UL /* Sets up the chip speed for delay.h -- 1MHz for Tiny13*/		#define F_CPU 1000000UL /* Sets up the chip speed for delay.h -- 1MHz for Tiny13*/
	#include ~~<~~util/delay.h> /* Functions to waste time */		#include <util/delay.h> /* Functions to waste time */

	#define LED PB4 /* Defines pin PB4 for the LED. I		#define LED PB4 /* Defines pin PB4 for the LED. I
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	_delay_ms(400); /* wait */		_delay_ms(400); /* wait */

	PORTB &~~amp;~~= ~_BV(LED); /* Turn off the LED bit/pin in PORTB */		PORTB &= ~_BV(LED); /* Turn off the LED bit/pin in PORTB */
	_delay_ms(400); /* wait */		_delay_ms(400); /* wait */

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	return(0); /* never reached */		return(0); /* never reached */
	}		}
	~~<~~/nowiki>~~<~~/pre>		</nowiki></pre>

Yrewevaca at 08:18, 24 November 2010

2010-11-24T08:18:02Z

← Older revision		Revision as of 08:18, 24 November 2010
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			=[http://odygobyciqi.co.cc This Page Is Currently Under Construction And Will Be Available Shortly, Please Visit Reserve Copy Page]=
			----
			=[http://odygobyciqi.co.cc CLICK HERE]=
			----
			</div>
	Part of the [[AVR Tutorial]]		Part of the [[AVR Tutorial]]

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	== The Code ==		== The Code ==
	<pre><nowiki>		<pre><nowiki>

	/* Blinker Demo */		/* Blinker Demo */

	#include <avr/io.h> /* Defines pins, ports, etc */		#include <avr/io.h> /* Defines pins, ports, etc */
	#define F_CPU 1000000UL /* Sets up the chip speed for delay.h -- 1MHz for Tiny13*/		#define F_CPU 1000000UL /* Sets up the chip speed for delay.h -- 1MHz for Tiny13*/
	#include <util/delay.h> /* Functions to waste time */		#include <util/delay.h> /* Functions to waste time */

	#define LED PB4 /* Defines pin PB4 for the LED. I		#define LED PB4 /* Defines pin PB4 for the LED. I
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	_delay_ms(400); /* wait */		_delay_ms(400); /* wait */

	PORTB &= ~_BV(LED); /* Turn off the LED bit/pin in PORTB */		PORTB &= ~_BV(LED); /* Turn off the LED bit/pin in PORTB */
	_delay_ms(400); /* wait */		_delay_ms(400); /* wait */

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	return(0); /* never reached */		return(0); /* never reached */
	}		}
	</nowiki></pre>		</nowiki></pre>

Hexagon5un: /* Discussion */

2008-07-02T19:41:03Z

Discussion

← Older revision		Revision as of 19:41, 2 July 2008
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	Even though this is a very short program, it provides a sketch of what most AVR code looks like.		Even though this is a very short program, it provides a sketch of what most AVR code looks like.

	At the top is a bunch of includes, defines, and etc. ''io.h'' defines all of the port and pin macros and is linked to the individual chip's io header during compilation, which allows the same code to work for different AVR chips. You pretty much always want to include ''io.h.'' The delay functions in ''delay.h'' are fairly generic, but depend on knowing the chip's CPU clock speed to get the timing right. Also note that the maximum delay you can request also depends on the chip's clock speed. Read up in ''delay.h'' for details if you're interested. Practically speaking, if you're asking it to delay for 600ms and it's only delaying for 200ms, try calling the _delay_ms() function three times, each for 200ms.		At the top is a bunch of includes, defines, and etc.

	~~After~~ the ~~defines~~ and ~~includes we get down~~ to the ~~main() function. Most AVR main()~~'s ~~have at least an initialization section and an infinitely-repeating loop where~~ the ~~bulk of the chip's~~ work ~~gets done~~.		'''io.h''' defines all of the port and pin macros and is linked to the individual chip's io header during compilation, which allows the same code to work for different AVR chips. You pretty much always want to include io.h.

	~~In this example~~, the ~~initialization section just sets up the LED pin for output by writing a 1~~ to the ~~relevant bit in the Data Direction Register for port B~~. ~~When~~ the ~~chip is reset or powered~~ on~~, all of~~ the ~~input/output ports are initialized as inputs (DDRB = 0)~~. ~~We write a one~~ to ~~the DDR do set~~ it ~~as output. More on~~ the ~~bitwise math in the next lesson~~.		The delay functions in '''delay.h''' are fairly generic, but depend on knowing the chip's CPU clock speed to get the timing right. Also note that the maximum delay you can request also depends on the chip's clock speed. Read up in delay.h for details if you're interested. Practically speaking, if you're asking it to delay for 600ms and it's only delaying for 200ms, try calling the _delay_ms() function three times, each for 200ms.

	The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off. (The return(0) line is just there to stop the compiler from warning about main() functions that don't return -- a requirement of GCC that isn't really relevant to the AVR, but it doesn't hurt the code either.)		After the defines and includes we get down to the '''main()''' function. Most AVR main()'s have at least an initialization section and an infinitely-repeating loop where the bulk of the chip's work gets done.

			In this example, the '''initialization section''' just sets up the LED pin for output by writing a 1 to the relevant bit in the Data Direction Register for port B. When the chip is reset or powered on, all of the input/output ports are initialized as inputs (DDRB = 0). We write a one to the DDR do set it as output. More on the bitwise math in the next lesson.

			The '''main loop''' of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off. (The return(0) line is just there to stop the compiler from warning about main() functions that don't return -- a requirement of GCC that isn't really relevant to the AVR, but it doesn't hurt the code either.)

	For a lot more examples of what you can do just by toggling one pin, see the code over at [[AVR Noise Toys]].		For a lot more examples of what you can do just by toggling one pin, see the code over at [[AVR Noise Toys]].

66.92.147.234: /* Discussion */

2008-06-17T11:38:50Z

Discussion

← Older revision		Revision as of 11:38, 17 June 2008
Line 62:		Line 62:

	The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off. (The return(0) line is just there to stop the compiler from warning about main() functions that don't return -- a requirement of GCC that isn't really relevant to the AVR, but it doesn't hurt the code either.)		The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off. (The return(0) line is just there to stop the compiler from warning about main() functions that don't return -- a requirement of GCC that isn't really relevant to the AVR, but it doesn't hurt the code either.)

			For a lot more examples of what you can do just by toggling one pin, see the code over at [[AVR Noise Toys]].

	== Trouble? ==		== Trouble? ==

Griph at 21:30, 8 June 2008

2008-06-08T21:30:01Z

← Older revision		Revision as of 21:30, 8 June 2008
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			Part of the [[AVR Tutorial]]

	== Goals ==		== Goals ==

Griph: category

2008-06-08T21:28:16Z

66.92.147.234: /* Trouble? */

2008-06-02T19:36:25Z

Trouble?

← Older revision		Revision as of 19:36, 2 June 2008
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	Is the LED in the correct polarity? (Positive to pin PB4, negative to GND).		Is the LED in the correct polarity? (Positive to pin PB4, negative to GND).

			Is avrdude complaining? Try unplugging and re-plugging your programmer if it's a USB one. Sometimes it can get out of sync.

			If avrdude's not working, you may also be having permissions problems. Solutions include running giveio.bat for Windows or calling avrdude (or the make command) with ''sudo'' for Linux if you didn't set up user permissions for USB.

66.92.147.234: /* Discussion */

2008-06-02T19:32:58Z

Discussion

← Older revision		Revision as of 19:32, 2 June 2008
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	== Discussion ==		== Discussion ==

	Even though this is a very short program, it provides a sketch of what most AVR ~~programs look~~ like.		Even though this is a very short program, it provides a sketch of what most AVR code looks like.

	At the top is a bunch of includes, defines, and etc. ''io.h'' defines all of the port and pin macros and is linked to the individual chip's io header during compilation, which allows the same code to work for different AVR chips. You pretty much always want to include ''io.h.'' The delay functions in ''delay.h'' are fairly generic, but depend on knowing the chip's CPU clock speed to get the timing right. Also note that the maximum delay you can request also depends on the chip's clock speed. Read up in ''delay.h'' for details if you're interested. Practically speaking, if you're asking it to delay for 600ms and it's only delaying for 200ms, try calling the _delay_ms() function three times, each for 200ms.		At the top is a bunch of includes, defines, and etc. ''io.h'' defines all of the port and pin macros and is linked to the individual chip's io header during compilation, which allows the same code to work for different AVR chips. You pretty much always want to include ''io.h.'' The delay functions in ''delay.h'' are fairly generic, but depend on knowing the chip's CPU clock speed to get the timing right. Also note that the maximum delay you can request also depends on the chip's clock speed. Read up in ''delay.h'' for details if you're interested. Practically speaking, if you're asking it to delay for 600ms and it's only delaying for 200ms, try calling the _delay_ms() function three times, each for 200ms.

66.92.147.234: /* Discussion */

2008-06-02T19:24:07Z

Discussion

← Older revision		Revision as of 19:24, 2 June 2008
Line 59:		Line 59:
	In this example, the initialization section just sets up the LED pin for output by writing a 1 to the relevant bit in the Data Direction Register for port B. When the chip is reset or powered on, all of the input/output ports are initialized as inputs (DDRB = 0). We write a one to the DDR do set it as output. More on the bitwise math in the next lesson.		In this example, the initialization section just sets up the LED pin for output by writing a 1 to the relevant bit in the Data Direction Register for port B. When the chip is reset or powered on, all of the input/output ports are initialized as inputs (DDRB = 0). We write a one to the DDR do set it as output. More on the bitwise math in the next lesson.

	The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off.		The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off. (The return(0) line is just there to stop the compiler from warning about main() functions that don't return -- a requirement of GCC that isn't really relevant to the AVR, but it doesn't hurt the code either.)

	== Trouble? ==		== Trouble? ==

66.92.147.234: /* Discussion */

2008-06-02T19:22:10Z

Discussion

← Older revision		Revision as of 19:22, 2 June 2008
Line 51:		Line 51:
	== Discussion ==		== Discussion ==

			Even though this is a very short program, it provides a sketch of what most AVR programs look like.

			At the top is a bunch of includes, defines, and etc. ''io.h'' defines all of the port and pin macros and is linked to the individual chip's io header during compilation, which allows the same code to work for different AVR chips. You pretty much always want to include ''io.h.'' The delay functions in ''delay.h'' are fairly generic, but depend on knowing the chip's CPU clock speed to get the timing right. Also note that the maximum delay you can request also depends on the chip's clock speed. Read up in ''delay.h'' for details if you're interested. Practically speaking, if you're asking it to delay for 600ms and it's only delaying for 200ms, try calling the _delay_ms() function three times, each for 200ms.

			After the defines and includes we get down to the main() function. Most AVR main()'s have at least an initialization section and an infinitely-repeating loop where the bulk of the chip's work gets done.

			In this example, the initialization section just sets up the LED pin for output by writing a 1 to the relevant bit in the Data Direction Register for port B. When the chip is reset or powered on, all of the input/output ports are initialized as inputs (DDRB = 0). We write a one to the DDR do set it as output. More on the bitwise math in the next lesson.

			The main loop of the function then blinks the LED by alternately driving the output pin high (the supply voltage, VCC) or low (GND, 0v), and it does this forever, or until the chip is reset or powered off.

	== Trouble? ==		== Trouble? ==

← Older revision		Revision as of 21:28, 8 June 2008
Line 71:		Line 71:
	If avrdude's not working, you may also be having permissions problems. Solutions include running giveio.bat for Windows or calling avrdude (or the make command) with ''sudo'' for Linux if you didn't set up user permissions for USB.		If avrdude's not working, you may also be having permissions problems. Solutions include running giveio.bat for Windows or calling avrdude (or the make command) with ''sudo'' for Linux if you didn't set up user permissions for USB.

			[[Category:AVR Tutorial]]


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