Paul Baker (Parallax) said...
hippy, if he got a 100Mhz oscillator, there's no need to do division, just set clkmode to xinput and don't use pll.
Aha; I'd realised the PLL could be over-clocked, I hadn't realised the XINPUT could be and the limit of 80MHz can be pushed as well. For me then, that would be the best solution; 100MHz module and no PLL.
If that's what you meant by "active external oscillator" we may be talking the same language. If we are, I was thrown by your saying they are only available in surface mount, as there seems to be quite a few suppliers of through-hole 100MHz modules.
We are indeed talking about the same thing, there probably are quite a few suppliers of through hole 100 MHz oscillators, I just didnt find any in my brief search.
Personally I wouldnt put a lot of time into getting non-SMD active oscillators. i just solder wire links directly to 3 of the pads (vcc,vss,out) at 90deg angles to the base, has always worked for me.
Fred Hawkins said...
deSilva,
am I correct in assuming that, per your diagram, that pins 1 and 8 get connected to the propeller? And that their order doesn't matter?
Fred
Pin #1 is N.C. If not, just ignore it. It seems SOMETIMES #1 and #8 are connected, but better just ignore #1.
Do you have an oscilloscop to check its output? As I said, I am not sure whether ALL oscillators work fine at 3V3. So if it does not work from the beginning, you COULD apply 5V to its Vdd, but then use a 100 to 220 Ohms series resistor between #8 and XINPUT. This is a kind of compromise to limit the current, as it also works as a lowpass with the 6pF input capacity, around 100 MHz
Fred + Desilva
Be aware :- re Xtal oscillators, sometimes ( depending on manufacturer )
Pin 1 can be OSC enable. Left floating may not work, or be unreliable, get a
data sheet, and tie high or low as recommended.
Best Regards
Ian
:- Blessed is the man who expects nothing, for he shall never be
disappointed.
Comments
am I correct in assuming that, per your diagram, that pins 1 and 8 get connected to the propeller? And that their order doesn't matter?
Fred
If that's what you meant by "active external oscillator" we may be talking the same language. If we are, I was thrown by your saying they are only available in surface mount, as there seems to be quite a few suppliers of through-hole 100MHz modules.
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.
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Holy parallel processing, Batman!
Do you have an oscilloscop to check its output? As I said, I am not sure whether ALL oscillators work fine at 3V3. So if it does not work from the beginning, you COULD apply 5V to its Vdd, but then use a 100 to 220 Ohms series resistor between #8 and XINPUT. This is a kind of compromise to limit the current, as it also works as a lowpass with the 6pF input capacity, around 100 MHz
>> Can you tell me the form factor and packaging of this crystal?
>> http://www.alltronics.com/cgi-bin/item/XTAL_6_25MHZ/search/6.25MHZ-CRYSTAL
<@alltronics.com> to me:
HC-18U with wire leads.
Be aware :- re Xtal oscillators, sometimes ( depending on manufacturer )
Pin 1 can be OSC enable. Left floating may not work, or be unreliable, get a
data sheet, and tie high or low as recommended.
Best Regards
Ian
:- Blessed is the man who expects nothing, for he shall never be
disappointed.