Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: krjariwala on March 28, 2010, 12:32:20 AM
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hi,
i m facing the problem of loading when i interface l298 with port 0 of 89v51 with 4.7k pullup.when i connect the logic pins of l298 the port pin shows an output of 1.65 volts else its 5V which is correct. what changes should i do?
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Hi,
i m facing the problem of loading when i interface l298 with port 0 of 89v51 with 4.7k pullup.
Why the pull-up?
when i connect the logic pins of l298 the port pin shows an output of 1.65 volts else its 5V which is correct. what changes should i do?
Which pins do you connect to?
With a max. load current of 100µA for a "High" input and a max. load current of 10µA for a "Low" input, even if the controller tries to pull low, the 4k7 pull-up will be the largest load with up to a theoretical 1mA (i.e. 100 times rhat of the L298).
So, something is clearly wrong!
Either you connected it up wrong or the controller or the L298 is shot.
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Or the port is set-up as an input not an output.
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i need pullups on port 1 ,0 and 2. i am using port 0.1 nad 0.2. also i tried on port 3 where there are no pull ups on p3.1 nad 3.2.
same problem occurs.
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one thing i have found is its working on channel 2 but not on channel 1. why does this happen?
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Hi,
Sounds like waltr was right, you are using the port as input.
Output ports don't need pullups.
Change the direction register and the problem should go away.
I'd recommend reading up on microcontrollers, perhaps read and follow a few beginners tutorials to get the gist of it.