| Author |
Message |
|
|
 Posted: May 15, 2012 - 12:58 PM |
|
Joined: Oct 09, 2009
Posts: 3
|
|
Hi all,
i have a strange problem with an ATmega32U2.
i have 3 pins on PORTB (PB5, PB6, PB7) as input the others are outputs (via DDRB = 0x1F).
At PB7 the internal pullup is enabled (PORTB =
0x80).
PB7 is not connected.
PB6 is connected to VCC with an external 4k7 pullup.
PB5 is connected with Y-Output (Pin5) from a HC151 (all MUX-Inputs of the HC151 are at VCC level)
In the main loop i print out the content of PINB register via UART.
If i power on the circuit then it gives me 0xE0 as PINB content (it means PB7,PB6,PB5 = 1) (like expected).
After 1-2 seconds it changes to 0x80 (it means PB6,PB5 = 0), but nothing was touched.
If i measure the level at PB5 and PB6 with a voltage meter, i see +5V for both ?!?!?!
if i tie PB6 (this one with the external pullup) to GND, the display keeps showing 0x80, if i remove the GND cable i see 0xC0 for a short time (it means PB7,PB6 = 1, PB5 = 0).
After this i see 0x80 again.
From where comes the internal AVR 0-level at PB6,PB5, even if i measure +5V with the meter ?
Thank you in advance.
Code:
int main(void)
{
UARTInit();
DDRB = 0x1F;
PORTB = 0x80;
for (;
{
UARTPrintNL ();
UARTPrintHex( PINB );
}
} |
|
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 01:33 PM |
|
Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
|
|
 |
_________________
Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 01:39 PM |
|
Joined: Oct 09, 2009
Posts: 3
|
|
|
Code:
int main(void)
{
UARTInit();
DDRB = 0x1F;
PORTB = 0x80;
for (;;)
{
uint8_t pinvalue = PINB;
UARTPrintNL ();
UARTPrintHex( pinvalue );
}
}
|
|
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 01:42 PM |
|
Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
|
|
| "My car is not working. Please help!" |
_________________
Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 01:50 PM |
|
Joined: Oct 09, 2009
Posts: 3
|
|
@MBedder:
the code is working. i only posted it again with code formatting.
Please read the first post. The problem is an AVR internal Low-Level read out from register PINB even if the voltage meter at these pins says: +5V.
Do you have some ideas on this ?
Thank you in advance. |
|
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 02:25 PM |
|
Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
|
|
|
transporter08 wrote:
the code is working... The problem is an AVR internal Low-Level read out from register PINB even if the voltage meter at these pins says: +5V.
"My friend is alive. The problem is that he's dead". 
To get help you have to post the entire code. |
|
|
| |
|
|
|
|
|
|
Posted: May 15, 2012 - 04:07 PM |
|
Joined: Jul 19, 2011
Posts: 460
|
|
transporter08,
Try disconnecting PB6 & PB5 from external circuits and configuring them with internal pull-ups (like PB7). Do you get the same result?
If not, reconnect externals one-by-one. Does oen of them cause the problem? |
|
|
| |
|
|
|
|
|
FAQ
Search
Register
Log in to check your private messages
Log in
Maximize
RSS
