DSCOPE: STRANGE BEHAVIOR OF THE SERIAL PORT

Information in this article applies to:

• C166 Version 3.12
• C166 Version 4.01
• C251 Version 2.14
• C51 Version 5.50

SYMPTOMS

I am using dScope to debug my application and I get unexpected behavior from the serial port. Right after moving something to the serial buffer, by using:

mov    sbuf, a

  an interrupt is generated two or three cycles later when it would normally wait for the transmission of the 10th bit before TI. I've set the serial port for 19.2K baud rate with timer 1 so that it should wait for around 50us * 10 = 0.5 ms before raising TI.   What am I doing wrong?

CAUSE

It sounds like the STIME vtreg is set to a value of 0 (this is the default).

RESOLUTION

Set the STIME vtreg to a value of 1. You can do that in the command window by typing:

STIME = 1

MORE INFORMATION

Refer to page 296 in the dScope for Windows User's Guide 01.97 for more information.

Last Reviewed: Wednesday, August 03, 2005