In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

Peter,

this is an interesting circuit to do an auto-reset. I never did domething like this so far, therefore, I can't tell if it can generate a "clean" reset. As you had mentioned, when the SX I/O pin goes low, controlled by the SX application, it will pull low the reset line, so the SX will perform a reset which makes the I/O pin go high-Z. So, most likely, the SX will reset. The question is if this relatively short high-low-high transition on the reset line is long enough to reset the BS. Actually, "low" does not mean 0 V - it is the remaining voltage across the capacitor that is just below the SX /MCLR low threshold level. The datasheet specifies this value as 0.2Vdd.

For auto-resetting an SX, I use another "trick": I activate the watchdog timer, and make sure that a clr !WDT is executed often enough in the "regular" pogram loops. When I want to do an auto-reset, I bring program execution into an endless loop where the watchdog timer is no longer cleared. This causes a reset as soon as the watchdog timer conter overflows. You could extend this to reset the BS by connecting one SX I/O pin to the BS reset line. At startup of the SX program, you then pull this pin low, long enough to safely reset the BS.

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=97605#m97606

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2005 (http://www.dotNetBB.com)