As I mentioned, the 3.3's I have used did more than fluctuate, the output sat at the full input voltage until I put the 10uF. If you happened to have hit the Vdd with 5V that may have done it. Just a guess.
Post Edited (originator) : 1/25/2007 4:27:43 AM GMT
Not to keep beating a 'dead horse'! But when I built my HBPDB·I used a LM2937-3.3 +3.3VDC voltage regulator. From the data sheet of this part, it states that:
** Required for stability. Cout must be at least 10 μF (over the full expected operating temperature range) and located as close as possible to the regulator.
I realize that you maybe using a different +3.3VDC regulator, however when I first built the +3.3VDC power supply, using the LM2937, on my HBPDB I left out the 10uF capacitor. When I first powered up the board, with out the Propeller chip installed, the +3.3VDC power supply was 'all over the place'. When I installed the 10 uF capacitor then I had a rock solid +3.3VDC power supply. I would double check the data sheet for the part that you are using.
I originally ordered four Propeller chips, back in May 2006 ($25.00 each!) and I'm still using the original Propeller chip, still have the three others in my parts bin. From my experience the Propeller chip (D40) has been quite robust and has survived everything I've thrown at it so far.
1) however you will notice that the line was scoped and there was no appreciable fluctuations#
2) Since the circuit was built on stripboard this evening I cannot kill it ? - same circuit
based on comments - I removed even the 0.1uf at output (and also removed the prop !)
measured and it was at 3.286v - and flat lined on the scope without any fluctuations even with
load attached ..
Mike Cook
Quoting the specs of the regulators you have used is fine - however I have out lined that the manufacturers of mine specified a 10uf in i/p cap and only if vin exceeds 28v - and none required ! on output with an output ripple difference of 5 - to 10mv with or without cap - so I have attached the data sheet for your perusal... where·possibilities are·include vin+ &·vin-·/ vin+ & GND.
I think by now it has been clarified that the reg o/p cap is not the issue - due to
1) measurements taken at all stages - yielding nothing fruitfull
2) Reg specs as attached - and requirement or lack there of o/p capacitors -
3) the same circuit was built on stripboard - same 'Kill' tests carried out -·and I did not manage to kill it.
however I·appreciate the feedback and think ·a) you all are a great group of helpful and enthusiastic people ·b) future props will be (at least) stripboarded ·c) the propellor rocks !
· finally I must go and make final arrangements for my 2 dead·props !
I have attached an image of a breadboard parallax propellor 40pin dil test circuit. You can see that I too am running dual regulators 5v for aux devices and 3.3v for prop. Ok maybe different regulators to yours but have 2 100uF caps on outputs of both 5v and 3.3v. I have Hot Pulled the prop, accidently shorted pins / connections, did not adhere in any great way to static handling - except for the odd touch of earthed devices,pulled connections while it was on etc etc - basically I have been very bold and it lives on.
I have used the max232 for serial connection with no issues even with laptop usb to serial devices of all flavours and I continue to be a bold boy with the prop and I have not killed one·,so i think there may be some fundamental issue with your layout.
God Bless Parallax.
Post Edited (QuattroRS4) : 1/25/2007 5:06:27 PM GMT
Comments
Post Edited (originator) : 1/25/2007 4:27:43 AM GMT
it would still run one cog, and blink any output led, but beyond that no go... ( it was in a propstick at the time)
definately not the fault of the propstick... just a absent minded expirementer..
replaced the prop, propstick works fine
Not to keep beating a 'dead horse'! But when I built my HBPDB·I used a LM2937-3.3 +3.3VDC voltage regulator. From the data sheet of this part, it states that:
** Required for stability. Cout must be at least 10 μF (over the full expected operating temperature range) and located as close as possible to the regulator.
I realize that you maybe using a different +3.3VDC regulator, however when I first built the +3.3VDC power supply, using the LM2937, on my HBPDB I left out the 10uF capacitor. When I first powered up the board, with out the Propeller chip installed, the +3.3VDC power supply was 'all over the place'. When I installed the 10 uF capacitor then I had a rock solid +3.3VDC power supply. I would double check the data sheet for the part that you are using.
I originally ordered four Propeller chips, back in May 2006 ($25.00 each!) and I'm still using the original Propeller chip, still have the three others in my parts bin. From my experience the Propeller chip (D40) has been quite robust and has survived everything I've thrown at it so far.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Mike
1) however you will notice that the line was scoped and there was no appreciable fluctuations#
2) Since the circuit was built on stripboard this evening I cannot kill it ? - same circuit
based on comments - I removed even the 0.1uf at output (and also removed the prop !)
measured and it was at 3.286v - and flat lined on the scope without any fluctuations even with
load attached ..
Mike Cook
Quoting the specs of the regulators you have used is fine - however I have out lined that the manufacturers of mine specified a 10uf in i/p cap and only if vin exceeds 28v - and none required ! on output with an output ripple difference of 5 - to 10mv with or without cap - so I have attached the data sheet for your perusal... where·possibilities are·include vin+ &·vin-·/ vin+ & GND.
I think by now it has been clarified that the reg o/p cap is not the issue - due to
1) measurements taken at all stages - yielding nothing fruitfull
2) Reg specs as attached - and requirement or lack there of o/p capacitors -
3) the same circuit was built on stripboard - same 'Kill' tests carried out -·and I did not manage to kill it.
however I·appreciate the feedback and think
·a) you all are a great group of helpful and enthusiastic people
·b) future props will be (at least) stripboarded
·c) the propellor rocks !
· finally I must go and make final arrangements for my 2 dead·props !
Thanks all - keep up the good work..
Post Edited (TE44) : 1/25/2007 6:03:38 AM GMT
I have used the max232 for serial connection with no issues even with laptop usb to serial devices of all flavours and I continue to be a bold boy with the prop and I have not killed one·,so i think there may be some fundamental issue with your layout.
God Bless Parallax.
Post Edited (QuattroRS4) : 1/25/2007 5:06:27 PM GMT