Logic Analyzer Signals testing bs2 are not accurate at all!!!!!!

rwgast_logicdesign

This is driving me nutty as im trying to learn as much as possible and im having a real hard time here, I just want to view the logic signals of the bs2 Im using a propeller based analyzer with 100mhz bandwith called propalyzer, and I have tied a voltage buffer to it to make the prop pins 5 volt tolerant. Now when I analyze a propeller everything looks fine for example if I flash an LED with a 50% duty cycle my waves are cleanly timed.

So let me explain to get this all out of the way and clear up any questions. I have a propeller board I made, which is overclocked and tested. I then have a wing plugged into it I made using a 74lvc244 which allows for 5 volt tolerant input.

Now I have a quick start programed to togle a pin with a 50% duty cycle im not sure what speed since i didnt save the code but here is what my separate propalyzer board shows me is happening when the the quickstart pin is probed through the 5v buffer wing I made

Ok im sorry about the quality of that I truly am!!!

Now here is some bs2 code

DO


  LOW 14
    PAUSE 2
  HIGH 14
    PAUSE 2


LOOP

I should see a a 50% duty cycle of 2ms but im not... im seeing this

The hi patches are roughly 2ms but not always, and this gets way worse when I use pulsout to drive a servo when I excpect to see 1ms Hi i see half a ms of these rapid hi/lows im just doing a simple PULSOUT 14, 500...

Im hoping some here can PLEASE help me figure this out, maybe someone else here uses a logic analyzer and can either confirm its the bs2 or something to do with my analyzer

rwgast_logicdesign

Ok so I just tested a 555 circuit oscillating to drive a speaker its hi was a little over 5v, I was testing this to make sure this didnt happen with all 5v devices and thats why it was happening to the bs2 and not prop, well the timing looked clean on a 555 too so now im figuring this is a bs2 thing

rwgast_logicdesign

OK so I figured out the problem with this whole thing I was testing pin 14 and i had a 470ohm resistor going to a current limiting led, for some reason the resistor was screwing up my reading when I read directly at pin 14 i get nice clean wave although the timing is showing about 1ms on and 1ms off instead of 2ms on and off... so idk whats up there

rwgast_logicdesign

Alright Alright SO.......

DO
PULSOUT 14, 1000
PAUSE 20
LOOP

Should generate a 2ms pulse correct?? becuase im only seeing a 1ms pulse

Phil Pilgrim (PhiPi)

OK so I figured out the problem with this whole thing I was testing pin 14 and i had a 470ohm resistor going to a current limiting led, for some reason the resistor was screwing up my reading ...

The input that the buffer was seeing was a series of pulses rising no higher than the forward voltage of the LED. If that happened to be close to the buffer's logic threshold, you could easily get what you saw on the scope.

Regarding the timing "errors" you're noting, I would bet that the Propalyzer settings need to be re-examined.

-Phil

rwgast_logicdesign

Ok thank you phil thank you, I never even thought about the LED Vf being a factor, in all this.

Have you used propalyzer at all? Jazzed told me to set it to 10us, which I have done what other setting could be awry here? I could list them change them if you see an error. Changing the resalution wouldn not cause timing errors would it? I like propalyzer becuase of the bandwith the only other thing I have that can be used as an analyzer uses sump and can only get 1mhz of bandwith, plus its a pita to flash the firmwares back and forth on it all the time as I use propalyzer for signals and the bus pirate for protocol decoding

rwgast_logicdesign

Ok im using a 5mhz crystal and propalyzer is set to 80,000,000 mhz, I just tried higher lower resalutions and also faster slower com port speeds, im still measuring the his as 1ms. Here is the code once again



DOPULSOUT 14, 1000PAUSE 20LOOP
Here is what im seeing I have circled the time stamps at the bottom when I move my cursor

Im really getting frustrated here as I know im doing something wrong but I cant figure it out, I would really like to be able to use propalyzer well I feel it could help me greatly as a learning tool