Burning up stuff is learning, right?
Ragtop
Posts: 406
I messed up a propeller in a new way for me anyway. I was using the demoboard's 3.3v power connection
to trip a 12vdc relay. After disconnecting and bringing the demoboard back to computer I get a RAM checksum error if
I F10 or F11 from the propeller tool.
When I F7 though, it returns that it found Propeller chip version 113.
Thinking I might should of used a bigger resister going to the transistor that charges the coil.
to trip a 12vdc relay. After disconnecting and bringing the demoboard back to computer I get a RAM checksum error if
I F10 or F11 from the propeller tool.
When I F7 though, it returns that it found Propeller chip version 113.
Thinking I might should of used a bigger resister going to the transistor that charges the coil.
Comments
RIP, P8X32A, you'll be missed!!
Education ALWAYS costs you something.
You can pay for it in a college, or you can pay for it in the field, but it always costs.
Sounds like you furthered your education this week, so all is good.
OBC
With all the excitement about a the Propeller 2, I'd think you'd be thrilled with a Propeller 113. (That is darn weird.)
Still not completely sure what happened. I still don't understand the concept of using the relay to separate the circuits but then having to drive the relay
with 12v connected to the propeller via a transistor.
I used a 330ohm resister from prop to transistor, I am assuming I should have went higher or I am wondering if I could use a 3.3v diode there.
Which way round was the diode?
(one way works, the other way = spitzundsparken)
The moral of this story is. I still haven't learned...
on wikipedia and it has the diode the other way round with band going toward ground.
You had the diode wired correctly. If you had used the diode the other way around you wouldn't have been able to trigger the relay.
What kind of diode did you use? I believe a fast acting Schottky diode is best for these applications.
When the relay is turned off, the coils resist a change in current which causes a voltage spike (higher than 12V) the diode lets the current die down at a more controlled manner. (It works something like that anyway.)
What transistor were you using? I don't know much about transistors but maybe someone else would know if it was appropriate or not for this application.
If F7 finds the prop all is not lost. I am unsure where you get 113 from.
I am presuming you mean ctl-F10 gives you a ram error. I was not aware that the prop will actually report an error from hub ram (and I have looked at the rom code before).
So lets dig a little deeper...
What program are you using to download? PropTool and version? bst, homespun?
Maybe even if you have damaged the prop you can find ways of using it.
Have you measured the voltages on the prop (maybe the regulator(s) have failed. Maybe the eeprom has failed.
FWIW, the prop is extremely robust, as many of us have found.
Oh, and driving the transistor, we need to know what one you are using, and the relay coil rating (current). Presume npn.
A series resistor of 1K - 4K7 to the base with a resistor from the base to ground of 10x the series resistor value would be good. The series value depends on the minimum gain of the transistor and the current required to pull-in the relay. The higher resistor the safer the design for protecting the prop.
You may have even blown the transistor and that could be causing you problems with the prop.
Bean
I was using F10 not ctrl-F10. Using Propeller Tool 1.2.7. The voltage coming out of the 3.3v VDD port is still 3.2 via my 2 dollar Harbor Freight multi-meter.
It is a 2N222 transistor. The relay's coil rating is nominal 12VDC with current 30ma. Coil resistance 400 ohms with pickup/dropout voltage 9/.6VDC
The diode was a Micro Commercial Components 1N4001, 1A 50V STANDARD RECOVERY RECTIFIER
It pays to have a schematic and a wiring diagram that shows the chips, pins, and connections as they really appear. Not that you won't still destroy stuff occasionally, it's just that the occasions will be less frequent.