[51] AT89C4051 what is the max current it can sink as input

[potatoo]

Hey,

i am a new to microcontrollers and trying to learn about this particular AT89C4051 microcontroller.

Let's say i wanna use PORT 1 as input port. The datasheet says P1.0 and P1.1 don't have internal pullups. I can't find the maximum input-low and input-high current values to apply to port as inputs.

Also it says P1.2-P1.7 has internal pullups. Does it mean that those pins will be read as HIGH if i dont connect anything to these ports? if so, for a LOW input do i only have to connect them to ground?

AT89C4051 Datasheet : http://www.atmel.com/Images/doc1001.pdf

 

[Allen6502]

Let's say i wanna use PORT 1 as input port. The datasheet says P1.0 and P1.1 don't have internal pullups. I can't find the maximum input-low and input-high current values to apply to port as inputs.

Used as input, just connect a 10K resistor on each PORT 1.0 and 1.1 as external pullups.

Also it says P1.2-P1.7 has internal pullups. Does it mean that those pins will be read as HIGH if i dont connect anything to these ports? if so, for a LOW input do i only have to connect them to ground?

yes and yes.

Allen

 

[ud23]

I can't find the maximum input-low and input-high current values to apply to port as inputs.

AT89C4051 Datasheet : http://www.atmel.com/Images/doc1001.pdf

Just read the page number 12 of the attached link in post#1 you know maximum and minimum port pin currents value.