I haven't looked the the schematic, but it is possible that the board has a pull-down on that pin, so by weakly pulling up you're getting a voltage divider. The IOIO pins can sink 20mA, so you can easily experiment with stronger pull-ups. The down-side of that would be that you usually want your pull resistor to assert some reasonable default state, so pulling up by default is not always a good solution. A simple solution that would work while leaving the (guessed) pull-downs to do their job is use a p-channel FET to pull to 5V, with the gate being weakly pulled to 5V too and connected to an open-drain, 5V tolerant pin on the IOIO. This will negate your logic (pulling low will cause the driver pin to go high), but will otherwise be just what you want.
On Tue, Sep 16, 2014 at 8:04 PM, Bill Carter <[email protected]> wrote: > I'm trying to run a motor controller board (rover 5) and the 'direction' > pin needs to be 0V or 5V. I wired it open drain with a 10k resistor to 5V > power and the IOIO can pull it low, but it will not go high to 5V with that > resistor. I'll have to use a lower ohm resistor to pull it up, apparently. > But I am concerned, the IOIO will probably have to be able to sink about as > much current as the motor controller pin will draw at 5V. > > How much is the max in open drain? Is it 20ma? What can I conveniently do > if the pin requires more? > > -- > You received this message because you are subscribed to the Google Groups > "ioio-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/ioio-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ioio-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/ioio-users. For more options, visit https://groups.google.com/d/optout.
