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#22334 Cannot Get Clean OnInterrupt Event from InterruptPort
Posted by
on 02 January 2012 - 09:13 AM
Hi there - happy new year!
I'm not an expert on the software side of inputs and interrupts.
However on the hardware side, I think you might be having a problem with switch contact bounce.
Thats where a fast digital circuit registers several transitions as the contacts of a switch come together. Basically the contacts don't snap together cleanly in one go - they bounce.
To rule this out as the cause, can you connect your 555 output directly to the Netduino input? (Voltage & hardware allowing)
Alternativly, add a new thread to your code that waggles an output pin eg D1 and connect it to your D0 pin.
Then monitor the events and see if the problem goes away.
If it does, you need to look at software (or hardware) to filter out the extra pulses when using the relay.
Paul
#21257 Total Newbie Temperature Project
Posted by
on 02 December 2011 - 02:16 PM
OK, firstly apologies for anyone who read my previous post this morning, there was one glaring error I made. Not a dangerous one, but one that meant the sensor would not have worked properly.
There are three issues with the circuit in the photographs.
These are simple mistakes and absolutely nothing to be ashamed of. I have done plenty worse in my time!
1/ There is no power routed to the sensor because the red and blue breadboard "bus bars" don't connect to anything else until you add extra jumper wires.
The bus bars in a bread board form conducting columns at the edge of the board. The rest of the holes are arranged as pairs of rows of 5 sockets. See BreadBoard.JPG diagram, the conductors look like a ladder with a gap in the rungs.
2/ I maybe wrong with this observation - apologies if I am wrong. It looks like you intended for the ground (GND) to be on row 8 of the breadboard, and the supply to be on row 11. It should be the other way around. Luckily the first issue means you did not add any power and cause damage.
I have attached a cutting from the data sheet for the LM35 showing the connections. Note that it shows them looking from underneath the sensor.
3/ Finally, the sensor needs a 5V supply not 3.3V.
BUT remember the previous discussions above - the Netduino cannot accept analogue inputs or an Aref of more than 3.3V. The sensor will not output more than 1.5V so that is OK, but you must NOT connect Aref to 5V, just leave it unconnected.
I don't have any LM35 sensors myself, but I have taken a transistor in a similar package and made a mock up of what I think the bread board and Netduino should look like using your original choice of wire colours.
Note the extra red and yellow wires to take the 5V supply and the ground to the sensor.
Photos below:
As always, I hope this helps.
Paul
There are three issues with the circuit in the photographs.
These are simple mistakes and absolutely nothing to be ashamed of. I have done plenty worse in my time!
1/ There is no power routed to the sensor because the red and blue breadboard "bus bars" don't connect to anything else until you add extra jumper wires.
The bus bars in a bread board form conducting columns at the edge of the board. The rest of the holes are arranged as pairs of rows of 5 sockets. See BreadBoard.JPG diagram, the conductors look like a ladder with a gap in the rungs.
2/ I maybe wrong with this observation - apologies if I am wrong. It looks like you intended for the ground (GND) to be on row 8 of the breadboard, and the supply to be on row 11. It should be the other way around. Luckily the first issue means you did not add any power and cause damage.
I have attached a cutting from the data sheet for the LM35 showing the connections. Note that it shows them looking from underneath the sensor.
3/ Finally, the sensor needs a 5V supply not 3.3V.
BUT remember the previous discussions above - the Netduino cannot accept analogue inputs or an Aref of more than 3.3V. The sensor will not output more than 1.5V so that is OK, but you must NOT connect Aref to 5V, just leave it unconnected.
I don't have any LM35 sensors myself, but I have taken a transistor in a similar package and made a mock up of what I think the bread board and Netduino should look like using your original choice of wire colours.
Note the extra red and yellow wires to take the 5V supply and the ground to the sensor.
Photos below:
As always, I hope this helps.
Paul
Attached Files
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BreadBoard.JPG 6.78KB
17 downloads
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LM35.jpg 13.04KB
25 downloads
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PICT0701.JPG 46.6KB
40 downloads
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PICT0705.JPG 44.87KB
33 downloads
- Arron Chapman likes this
#21249 Total Newbie Temperature Project
Posted by
on 02 December 2011 - 07:58 AM
I made a mistake in this post. Which I did not spot until I was at work.
I am re-writing it now.....
Paul
- Arron Chapman likes this
