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

Hello Stef,

I usually just tie the RTCC pin to gound on my projects.  An easy way to do it is just create a small solder bridge from the RTCC pin to the groud pin next to it.  This is what I normally do on my SX48 DIP module:

[url]http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=166781[/url]

In regards to the resonator it may not be the problem since you've tried another with the same results.  On the other hand if you've tried the exact same brand perhaps it is something odd with that and perhaps a different brand of resonator might give better results.

When using the resonator besides a small cap there is often a 10K resistor used as well.  You can clearly see this as it is used on the Parallax BS2p40 Stamp module:

[url]http://www.parallax.com/dl/docs/prod/schem/BS2p40SchematicRevD.pdf[/url]

What board do you have the SX48 chip mounted on?  Is the Parallax SX48 Protoboard or some board that you designed?  If it is your board is it one that you've etched yourself or one that you designed and had fabricated?  The layout of the traces can adversely effect performance and cause erratic behavior.  Is the resonator close to the CPU?  Speeds like 4Mhz are far more forgiving than 50Mhz.  The faster you go the more critical the board layout becomes.  At high speeds you need to start thinking more along the lines of RF and analog design than purely digital.

Just a few things to consider.

Robert

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