The autobaud algorithm I'm referring to is the default Atmel autobaud algorithm associated with the bootloader (invoked by hardware condition). And yes, the data is getting to the microcontroller (via a MAX3223). Also, the signal integrity is fine as viewed on a LeCroy oscilloscope. As for the specific application, I'm using Windows 98 SE Hyperterminal, though I must confess I'm unclear on the relevance. Please accept my apology for an unclear question and allow me to rephrase.
When initializing an Atmel AT89C51Rx2 to the default bootloader through hardware conditions, how many "U" characters should one expect the autobaud algorithm to require before completing its calculations and echoing back a "U" character (assuming everything is working properly)? Is this an algorithm that comnletes after a single character is sent, or should I expect it send ten or twenty or a couple hundred before it finishes?
Since it's been over a decade since I've fooled with any microprocessor circuits, and since I've never worked with an 8051 based microcontroller before, I might be better off asking what the most common "newbie" errors are? So I'm asking that too. Other than frequency matching errors, is there something else I should be looking at? Again I appreciate any and all help. Thanks.