AVR-Chat

basic stuff I know but Im banging my head against a wall

Im trying to READ a pin (see if Its set high or low by a switch and 
turning on another testpin - LED on the basis of that
the (supposedly) input pin is on PinE1 (on testpin2)
the output pin iis on PINEo (Testpin 1)

this is my definitions
#define TESTPIN2  	(PINE, 0x01)
#define TESTPIN1_HI  sbi(PORTE, 0x00)
#define TESTPIN2_HI  sbi(PORTE, 0x01)
#define TESTPIN2_IN cbi(DDRE, 0x01)
#define TESTPIN1_LO  cbi(PORTE, 0x00)
#define TESTPIN2_LO  cbi(PORTE, 0x01)

 //init_devices();

 while (!stop)
      { 
                TESTPIN1_HI; //light led
		TESTPIN2_IN;//set direction of input pin (DDRE)
		
		if ((TESTPIN2 == 0) //if switch is off
		   TESTPIN1_LO;

     }
but nothing happens after the led comes on the first time
regardless of the polarity put on the TESTPIN2

can anyone help?

thanks
Bren

Hi,

> but nothing happens after the led comes on the first time
> regardless of the polarity put on the TESTPIN2

I might be wrong but I think you'll find you can't set BITs on PORTE.
I think you can only write a BYTE...

Paul

You have several errors in your code.
1. Your "if" statement is bogus.  Expand it out:

if ((PINE, 0x01) == 0)

Doesn't mean anything, although syntactically it is ok.

2. After reset all pins are INPUTS.  You need to set the direction to OUTPUT
to properly drive the LED.

3. Which compiler are you using?  If a recent GCC then you can skip the bit
manipulation macros and perform direct operations on the ports. The compiler
will do the right thing.  E.g.:

#define TESTPIN2 (1<<2)	// 0x02
#define TESTPIN1 (1<<1)	// 0x01

while (!stop)
{
	DDRE |= TESTPIN1;		// Make output
	PORTE |= TESTPIN1;	// Drive high
	if (PINE & TESTPIN2)	// Test input
		PORTE &= ~TESTPIN1; // Clear output (drive low)
}

Cheers!

-----Original Message-----
From: inpactmicro [mailto:brendan.oflynn@nmrc.ie]
Sent: Thursday, February 19, 2004 8:29 AM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] reading a pin


   basic stuff I know but Im banging my head against a wall

Im trying to READ a pin (see if Its set high or low by a switch and
turning on another testpin - LED on the basis of that
the (supposedly) input pin is on PinE1 (on testpin2)
the output pin iis on PINEo (Testpin 1)

this is my definitions
#define TESTPIN2  	(PINE, 0x01)
#define TESTPIN1_HI  sbi(PORTE, 0x00)
#define TESTPIN2_HI  sbi(PORTE, 0x01)
#define TESTPIN2_IN cbi(DDRE, 0x01)
#define TESTPIN1_LO  cbi(PORTE, 0x00)
#define TESTPIN2_LO  cbi(PORTE, 0x01)

 //init_devices();

 while (!stop)
      {
                TESTPIN1_HI; //light led
		TESTPIN2_IN;//set direction of input pin (DDRE)

		if ((TESTPIN2 == 0) //if switch is off
		   TESTPIN1_LO;

     }
but nothing happens after the led comes on the first time
regardless of the polarity put on the TESTPIN2

can anyone help?

Thanks
for the advice ill give it a shot
im using The ICC compiler
(coming from a PIC background)
things seemed to be much more straightforward 
with PIN (bit) manipulation
setting Tris registers and reading pins was a simple operation
e.g 
TRISE1 = 1; // output
if (RE1)
   RE2 = 1; //if PIN E1 is high, light the LED on PIN E2
 
it just seems more complicated with the AVRs
are there macros set up to emulate this? 
(forced to use ICC by IT dept here)

--- In AVR-Chat@yahoogroups.com, "Larry Barello" <yahoo@b...> wrote:
> You have several errors in your code.
> 1. Your "if" statement is bogus.  Expand it out:
> 
> if ((PINE, 0x01) == 0)
> 
> Doesn't mean anything, although syntactically it is ok.
> 
> 2. After reset all pins are INPUTS.  You need to set the direction 
to OUTPUT
> to properly drive the LED.
> 
> 3. Which compiler are you using?  If a recent GCC then you can skip 
the bit
> manipulation macros and perform direct operations on the ports. The 
compiler

> will do the right thing.  E.g.:
> 
> #define TESTPIN2 (1<<2)	// 0x02
> #define TESTPIN1 (1<<1)	// 0x01
> 
> while (!stop)
> {
> 	DDRE |= TESTPIN1;		// Make output
> 	PORTE |= TESTPIN1;	// Drive high
> 	if (PINE & TESTPIN2)	// Test input
> 		PORTE &= ~TESTPIN1; // Clear output (drive low)
> }
> 
> Cheers!
> 
> -----Original Message-----
> From: inpactmicro [mailto:brendan.oflynn@n...]
> Sent: Thursday, February 19, 2004 8:29 AM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] reading a pin
> 
> 
>    basic stuff I know but Im banging my head against a wall
> 
> Im trying to READ a pin (see if Its set high or low by a switch and
> turning on another testpin - LED on the basis of that
> the (supposedly) input pin is on PinE1 (on testpin2)
> the output pin iis on PINEo (Testpin 1)
> 
> this is my definitions
> #define TESTPIN2  	(PINE, 0x01)
> #define TESTPIN1_HI  sbi(PORTE, 0x00)
> #define TESTPIN2_HI  sbi(PORTE, 0x01)
> #define TESTPIN2_IN cbi(DDRE, 0x01)
> #define TESTPIN1_LO  cbi(PORTE, 0x00)
> #define TESTPIN2_LO  cbi(PORTE, 0x01)
> 
>  //init_devices();
> 
>  while (!stop)
>       {
>                 TESTPIN1_HI; //light led
> 		TESTPIN2_IN;//set direction of input pin (DDRE)
> 
> 		if ((TESTPIN2 == 0) //if switch is off
> 		   TESTPIN1_LO;
> 
>      }
> but nothing happens after the led comes on the first time
> regardless of the polarity put on the TESTPIN2
> 
> can anyone help?