Using P0 port for driving +3.3 V Devices

Hello,

Thanks for the prompt reply.

Sorry for the incomplete information. The details are as follows.

The Controller is Atmel make AT89S52, 8 bit micro controller with 4K bytes of in system programmable flash. This controller is compabile with industry standard 8051 for general functions and IO pins.

The control functionality we are proposing is two way for the same port i.e it will be used as write as well as read pin for sending the command and acquiring the data from same port.

With regards

Hello,

Thanks for the prompt reply.

Sorry for the incomplete information. The details are as follows.

The Controller is Atmel make AT89S52, 8 bit micro controller with 4K bytes of in system programmable flash. This controller is compabile with industry standard 8051 for general functions and IO pins.

The control functionality we are proposing is two way for the same port i.e it will be used as write as well as read pin for sending the command and acquiring the data from same port.

With regards

for most (and I believe the AT89S52 - check the datasheet) old fashioned '51 derivatives P0 is 'open drain' which means that there is no pullup on the pins. Thus if you pull up with resistors connected to 3V3 this will, for output be a 3V3 bus. For input to PO you will have to check the output range (Voh Vol) of your other chip vs the input range of (Vih Vil) the AT chip and beware that you maintain a decent noise margin.

Erik

Thanks for the information.

With regards