hi Deepak,


1. Level translator will be required as Mr. Taylor suggests.

2.in your schematic R3 and R4 are not required although there existance will not be harm full. RD2BN permits p2.6 and p2.7 to be in any state. see folowing note at bottom of page 5 of AN461.

"P2.6 and P2.7 are not required to be in any Particular state in the 2nd generation P89C51Rx2 devices. These devices are distinguished by the absence of an “H” in the suffix."


3. same way R1 is not required as these devices have on chip pull down resistor on reset RST.

'RRST Internal reset pull-down resistor min 40- max 225 kW'


abhishek