problem with GPIO internal Pull up

[lum]

Posted on March 15, 2006 at 08:54

problem with GPIO internal Pull up

[lum]

Posted on March 14, 2006 at 06:38

Hi,

I can't set the P0.10 gpio pull up internal resistor.

I'm using the STR710 library and the following code:

//set the P0.10 in pull up/ pull down weak input mode

GPIO_CONFIG(GPIO0, 0x0400, GPIO_IPUPD_WP);

//Set the pull up resistor

GPIO_BITWRITE(GPIO0, 10, 1);

NB : I'm using a raisonance evaluation card with a str712f microcontrollers.

Thanks.

[donald]

Posted on March 15, 2006 at 08:46

P0.8 and P0.10 are ''true'' open drain rather than being push pull.

I put the question to ST about P0.8 and they indicated that the week pull up is NOT available on this pin (as part of it's 5V tolerance I believe).

The doco does not advise that weak pull up is not available.

Even after you move it to another pin be careful. If you use the library, when you change a different output pin on the same port you can change your pull ups to pull downs. This is because they do a read modify write on the port data register. When it is read it reads the INPUT state and when you write it back it sets the pull down polarity.

[lum]

Posted on March 15, 2006 at 08:54

thanks a lot for these informations.