Simple newbie questions
Beagle123
Posts: 1
Hi all:
I can't find anything about ADC inputs to the propeller chip.· So it doesn't have any ADC inputs?
According to the datasheet, its a 3.3v chip, and the pins can tolerate up to 3.6v (plus or minus 0.3v).· So If I'm using other 5v haardware how do interface it?· For example if I use the ADC chip at 5v, can I just connect the outputs directly to the pins eventhough the propeller datassheet says that its over the limit?
The data sheet aslo say that the chip can handle about 100mA current (and 1 watt).· Does that mean that I must use a resistor to limit the current?· If I connected the output of a 3.3v voltage converter directly to the power pin would that be bad?· Please advise.
I have a hall sensor that aabsolutely needs 5v or it will puke strange numbers.· So I have to run it at 5v.· Can its output be connected directly to a propeller pin?· Should I add a resistor?
That's actually a general question I have about all electronic components.· WHen their datasheet gives "maximum" limits for current does that meaan I have to use resistors to create that current?· HOw can I tell what a component needs?·
If I hook up a battery directly, will it just fry all this stuff?
Thanks in advance
Eric
·
I can't find anything about ADC inputs to the propeller chip.· So it doesn't have any ADC inputs?
According to the datasheet, its a 3.3v chip, and the pins can tolerate up to 3.6v (plus or minus 0.3v).· So If I'm using other 5v haardware how do interface it?· For example if I use the ADC chip at 5v, can I just connect the outputs directly to the pins eventhough the propeller datassheet says that its over the limit?
The data sheet aslo say that the chip can handle about 100mA current (and 1 watt).· Does that mean that I must use a resistor to limit the current?· If I connected the output of a 3.3v voltage converter directly to the power pin would that be bad?· Please advise.
I have a hall sensor that aabsolutely needs 5v or it will puke strange numbers.· So I have to run it at 5v.· Can its output be connected directly to a propeller pin?· Should I add a resistor?
That's actually a general question I have about all electronic components.· WHen their datasheet gives "maximum" limits for current does that meaan I have to use resistors to create that current?· HOw can I tell what a component needs?·
If I hook up a battery directly, will it just fry all this stuff?
Thanks in advance
Eric
·
Comments
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Post Edited (Leon) : 3/2/2008 10:46:25 AM GMT
The Propeller Education Kit Labs·sticky is a good source how to set up your circuits, see also the demoboard schematic pdf that is installed along with the Propeller Tool.
In the Education Labs you also find some examples of adc.
Post Edited (Clemens) : 3/2/2008 10:57:20 AM GMT
Probably best you take a look at the hardware sticky (top of forum page, but here's the link anyway: http://forums.parallax.com/showthread.php?p=667581
HTH.
Doh - Clemens can type quicker than me LOL
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Cheers,
Simon
www.norfolkhelicopterclub.co.uk
You'll always have as many take-offs as landings, the trick is to be sure you can take-off again ;-)
BTW: I type as I'm thinking, so please don't take any offense at my writing style
For most things you can just use a resistor in series with the input. If the pin is only going to be an output than you don't really need the resistor. Have a look at the sticky threads at the top of the propeller chip forum index.
You don't need and shouldn't use a resistor on the power supply pins. Just attach them straight to the output of the regulator. However, it would be a good idea to connect some capicators between the 3.3V supply and ground.
See above.
Depends on the battery that you are using. If it is a single cell lipo than you can probably get away with it. However, it is a good idea to use a regulator if you have one. It would be an even better idea to use a plug pack as then you won't have to change batteries
On data sheets you will often see a maximum current and voltage. You need to ensure that you don't go over these limits as you could fry your component if you do. To get a current you need a voltage difference and some kind of connection between the points that have a voltage difference. The connection between the two points will some level of resistance to current flow. For a wire this can be very low and for some resistors it can be extremely high. These three elements current(I), voltage(V) and resistance(R) are linked by this equation.
V=IR
or rearranging
I=V/R
Now say that you have one of the pins on your propeller hooked up to a resistor(1000ohms) connected to ground(0 volts) and the pin is set to output a 1(3.3V) than we have a voltage difference of 3.3V(3.3-0). If we plug this and the resistance into the formula above than we get a current of
I=V/R=3.3/1000=3.3mA
As the propeller can supply upto 50mA per pin this is will cause no problems at all.
To answer the second part of your question resistors don't really create current, its the voltage difference that creates current.
If you get a demo board than it comes with all the components needed to use your propeller. It will plug into a mouse, keyboard, tv, computer monitor, speakers/headphone and a microphone.
Edit: obviously I am the slowest typer of all
Post Edited (stevenmess2004) : 3/2/2008 11:29:36 AM GMT
But this looks like a real candidate for a newbie sticky...
I agree "But this looks like a real candidate for a newbie sticky..."
I'd also like to see a sticky with your excellent work on powering the Prop with batteries. I know you've done a lot of work in this area.
Rgds, David