Re: 8051

[EMAIL PROTECTED] (Brian Farmer) wrote in
news:[EMAIL PROTECTED]: 

> I am using Atmel's 20-pin 8051. My question is how do I assign Port 1
> as an output, becuause once I program the chip I have to reset it once
> to get it to not have P1 floating. After the reset it works fine. I
> don't assign the P1 direction one way or the other for now.

Write a 1 to the port SFR before reading it as input. For ouput, just
write your value - done. The pseudo-bi-directional nature of the ports is
both nice and a real pain. See Intel's scanned PDF copy of the MCS-51
User's Manual available on their website for a nice picture of the port
structure. Note that P0 and P2 will require pullups but you don't have
them on the 2051. 

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