set gpio drive strength
I've been searching for a few days now but it has been unsuccessful. How do you set the output strength of a gpio pin? at current I am using gpio 24, a multimeter indicated a current of about 40ma (think this is due to only the 1 pin being in use). I want to be able to adjust it to about 10ma
Re: set gpio drive strength
If you need less than it is capable of providing I do not understand what the problem is.strebor27 wrote:I've been searching for a few days now but it has been unsuccessful. How do you set the output strength of a gpio pin? at current I am using gpio 24, a multimeter indicated a current of about 40ma (think this is due to only the 1 pin being in use). I want to be able to adjust it to about 10ma
If you are woried about drawing to much current do to a design that could provide a dead short then add an apropriate resistor.
If you want to step it up use a line driver.
I do not think that you can directly change the Drive strength of GPIO.
I have never woried about it as everything that I am doing goes through either a Line driver, a Buffer, or a Buss driver.
Is there another issue that I am somehow missing?
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Re: set gpio drive strength
The following might be of interest:
Main GPIO how-to: http://www.raspberrypi.org/wp-content/u ... herals.pdf
Errata: http://elinux.org/BCM2835_datasheet_errata
Elaboration of GPIO drive: http://www.scribd.com/doc/101830961/GPIO-Pads-Control2
The last is the the bit you need for drive-strength
Note that the drive-strength is not the maximum current a pad will drive into a short circuit; it's only the maximum current that guarantees the desired logic level.
So reducing the drive-strength won't reduce that 40mA short-circuit current, and it won't prevent the SoC from dying.
Main GPIO how-to: http://www.raspberrypi.org/wp-content/u ... herals.pdf
Errata: http://elinux.org/BCM2835_datasheet_errata
Elaboration of GPIO drive: http://www.scribd.com/doc/101830961/GPIO-Pads-Control2
The last is the the bit you need for drive-strength
Note that the drive-strength is not the maximum current a pad will drive into a short circuit; it's only the maximum current that guarantees the desired logic level.
So reducing the drive-strength won't reduce that 40mA short-circuit current, and it won't prevent the SoC from dying.