SX 48/52 Proto Board and 50 Mz Resonator problems

RW Senser

Greetings.·· I've been successfully running an SX 48/52 Prototype board, with an SX52, at 50 MHz using the SX-Key and/or a·50 Mhz TTL Oscillator 4-pin can.· When I try the 50 MHz (Murata) Resonator (part 250-05060), the circuit runs well for 5-30 seconds and then hangs or goes "random".· Pushing the reset button restores the correct behavor for another 5-30 seconds.

Has anyone been able to successfull use the 50 Mhz Restonator with SX52 Proto board?· I've tried several resonators.....

And a second question: has anyone tried using the SX52 internal oscillator with SX/B programs that use SERIN/SEROUT?· It appears to me this is not a reliable configuration.

Any thoughts/feedback appreciated.

RW Senser

Sawmiller

do you mean the lil blue blob with 3 pins, yes i have used that on my sx 48/52 proto boards , got one running on the boe bot chassiss right now... i plug them in at the "x2 spot"·3 pins.... as for the internal clock, no that is not any good for using with serin and out... didnt get good connection with my lcd till i went to a external resonator
dan

Bean

RW Senser,
Try changing the OSC parameter on the device line.
I use OSCHS1 with a 50MHZ resonator and everything works fine.
I also recommend using BOR42 for reliable startup.
Bean.

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RW Senser

Hi Bean,

Thanks for the suggestions. Some interesting results:

1) Using BOR42 is a good step, no "odd starts"
2) Using OSCHS1 did change the behavior. The hangs and random behavior ended but the chip is running at 1/2 or 1/4 of the expected (and needed) speed.

I've decided just to stay with the TTL 4-pin can for now. Perhaps the particular Proto board I have has an issue.

Thanks again for the assist,
RW Senser

LoopyByteloose

Also, I just wonder if there is any chance that it would run better at 3.3volts.
One could change the regulator. It certainly lowers EMI spikes which might contribute to the problem.
Of course that lowers the BOR42 to BOR27 which may put you back into difficulties.

If the TTL crystal and the SXKey both clock the board at 50Mhz, it would seem to not be the board in particular.
Maybe an impedance mismatch with the Murata. There is a place to tweak it with plugging in capacitors.
You would likely need a scope to get things right though.

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Bill Franke

You might try putting a 100k ohm resistor across the two outside pins of the resonator. Some applications call for this.

LoopyByteloose

The resistor is a good idea, but I have seen 1 meg mentioned too. It can be plugged in.

I am not really comfortable with just saying the board or the chip has a personality.
The truth is that everyone would like plug and play with infinite options, but oscillators and crytals from dozens of sources may require fine tuning [noparse][[/noparse]with a scope and/or frequency counter]. So they hang up.

Then, once you get an optimal set up for a particular frequency with similar component from same source, you might duplicate it sucessfully many times. Also, there are a lot of 'sloppy' oscillator setups that will work and waste power, so working down from a high power FUSE setting to a lower power FUSE setting may hang.

I suspect that when you drive the properly tuned oscillator with less power, you will have less problems with the Brown Out as potential EMI reflected into the power lines is not driven as much.

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan