114Mhz Propeller 1 @ $0.55
Alexis64
Posts: 42
Hi,
We've been testing the propeller's speed while running our telemetry units as well as a variety of graphic video drivers and we've found that using a 14.31818Mhz Crystal ($0.55 at digikey) will reliably clock the Propeller at 114,54544 Mhz with a pllx8 ... The test was conducted at different temperatures for the past 48 hours.
Now that you have this information, go and get a 14.31818Mhz Xtal (or rescue it from surplus PCBs) and start developing a better, cooler, video driver
...
P.S. both the loaded (18pf caps) and the unloaded crystal worked fine - although I personally prefer the 18pf loaded crystal
The beginning of your demos (like graphics.spin etc) will need to be altered as follows:
We've been testing the propeller's speed while running our telemetry units as well as a variety of graphic video drivers and we've found that using a 14.31818Mhz Crystal ($0.55 at digikey) will reliably clock the Propeller at 114,54544 Mhz with a pllx8 ... The test was conducted at different temperatures for the past 48 hours.
Now that you have this information, go and get a 14.31818Mhz Xtal (or rescue it from surplus PCBs) and start developing a better, cooler, video driver
...P.S. both the loaded (18pf caps) and the unloaded crystal worked fine - although I personally prefer the 18pf loaded crystal
The beginning of your demos (like graphics.spin etc) will need to be altered as follows:
_clkmode = xtal1 + pll8x _xinfreq = 14_318_180Video: http://www.youtube.com/watch?v=rd12opYAa3Y
Comments
However, overclocking is reliant on the proper decoupling capacitors right at the prop power pins. What prop are you using? (DIP or QFP) I found the DIP prop seems to perform slightly faster. Sapieha has run my TriBlade at 120MHz using 15MHz xtal for many months. There is another thread about proper decoupling and speeds.
-Phil
IIRC Chip said the osc was actually specd to run at 14.31818MHz tops. I do know my RamBlade fails at 7.3xxMHz. I had looked for a 7MHz xtal but no luck so far (cheap and readily avail). I was interested to see where the prop actually fails in both 8x and 16x.
Of course, we really do not know whether the whole chip works at these higher frequencies, only that our programs work.
I now have 2 standard xtals in use... 6MHz (96MHz) for any USB work and 6.5MHz (104MHz) otherwise, with 13.5MHz (108MHz) supplied as an option.
http://www.mouser.com/ProductDetail/ABRACON/ABLS-71240MHZ-10-R70/?qs=GgB7MJ%2fTIsRM5YcMOZ2k3g%3d%3d
how about 7.2mhz?
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=478-4346-1-ND
with Load Capacitance of 18pF
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=SER3412-ND
Something like:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=535-9874-1-ND
I am pondering an attempt to run the Propeller 1 at 3.8V, as the max stable frequency seems to increase with operating voltage, and Chip seems to imply that they have successfully run the Prop at up to 5V (look at post #4 in http://forums.parallax.com/showthread.php?85474-How-to-safely-interface-a-5v-signal-to-the-propeller-See-Post-Reply-104 ) (though he says not to do so) for a short time. If that does work, then it should be possible to run the Propeller at up to 130MHz with 3.8V at usable temps, if I am reading the graph in the Propeller Data Sheet correctly.
qfp44
The only DIP40 that loved 13-14MHz Xtals was the one that I tested at 9 Volts. R.I.P.
Pullmoll got the Nascom emu running and the interest wained.
As Mike Green has pointed out, running the Propeller beyond normal operating voltages will stress the chip even when performance appears normal, and can result in shortening the props life span.
Does the prop have any rise in temperature?
Do folks use extra cooling when overclocking micros? The PC overclockers say that a 20% overclock doesn't significantly affect life as long as the temps are kept at low (closer to room) temperature. Of course an overclocked PC is obsolete after 6 months so maybe "life span" is defined differently in these contexts.
It's been running for 3 days now (running full graphics screens) and honestly, the QFP44 does not seem to be any different in temperature than a similar board testing next to it running @ 5Mhz ... I am sure (logic dictates) that there will be a difference in power consumption and temperature, however how much of a difference still need to be determined.
http://www.youtube.com/watch?v=rd12opYAa3Y
The Prop, 512KB memory and the EEPROM weren't so charitable.
As for cooling I found that the Prop could sometimes read a SD card when frozen but not at room temp. That turned out to be unwanted capacitance or an open circuit lead (stub)
But imagine the high they must have felt up to the very end!!
-Phil
"Friends don't let friends do Vin."
However, your test is not substantial enough to prove anything of value for a chip "population" sample. YMMV and especially OUMMV. That is "other users' milage may vary" which is important.
You should also add temperature variations and low voltage in addition to high voltage for "four-corners" test. Limits specified by the processor should be used. Of course all 8 COGS have to be running flat out with CTRA/CTRB operational; running video only tests PLL mode on one counter. Once you have a fully qualified test, you can run "four-corners" test with each crystal frequency. Each corner should ramp to target temperature within an hour and soak for 8 hours at least twice. After that you can do MTBF life testing.
Heater:
What type of code would you recommend to provide the most even over all test for all cogs. As to thermal testing My equipment available will limit me to more crude methods.
Read and enjoy the benefit of their engineering.
The results of my testing will definitely be YMMV/OUMMV, though I would still wish to test as thoroughly as I can. So what type of code would be needed to fully test out all cogs to there limits in every way that matters? I will be using as good of a cross section of Props as I can with my limited resources.
Also:
Is it possible to produce a 1 pin signal with a counter that can be used by the PLL on another Prop? If so I could use a Propeller to generate the clock for testing, and not be limited by the frequency of available crystals.
It would be good to have a functional sanity check test which could check every function that could be run periodically. That test is a little harder to specify and I don't have time for researching that just now.
Just using one counter out of spec will heat up a propeller chip. A temperature probe from a DMM would be good for monitoring that.
Yes, this can be done easily. You could also use the other propeller to verify the second counter in NCO mode on the test target's COGs are running. Testing with crystals would give better qualified data since it approximates typical use, but you could at least verify some basic assumptions by generating different clocks.
That is exactly what I used to test the prop frequencies - Chip wrote that object a few years back - it's in the OBEX ...
The prop runs very cool and this is one of the reasons overclocking works so well. When we started discussing 100MHz operation, we got a very unofficial nod that it was probably ok from Chip. overclocking does require special decoupling at the prop pins and there is a thread devoted to this.
Sounds like I will not have a problem then. I am currently running 4 test Props at 130MHz with a supply of 3.8V, lets see what happens.
-Phil
I agree with you, on using the PLL16 setting. I do not agree with the 8MHz limit, as I am using 8.125MHz (with PLL16X, for 130MHz) for the 4 test props running on my bench at this time, and will be increasing that if all goes well.