Propeller Education Kit
Michael Popoloski
Posts: 42
I finally got to use my Propeller education kit today, and I must say that everything is very nice. The only problem is, I cannot get the Propeller to communicate with the PC.
I have downloaded and installed the drivers, and the Plug itself is detected correctly. The problem is that the LED doesn't light when the 9V battery isn't plugged in, even though the USB cable is connected. I tested the voltage on the prop plug when it was not connected to the board, and it read a steady 3.3V. But when plugged into the board, it barely reads 1.5. The Propeller chip itself is drawing all the power, because when I take it off the board the voltage on the prop plug pins goes back to 3.3V.
Any ideas on how to make the LED light? The setup and testing lab doesn't has tons of information for troubleshooting, but none of it seems to help.
I have downloaded and installed the drivers, and the Plug itself is detected correctly. The problem is that the LED doesn't light when the 9V battery isn't plugged in, even though the USB cable is connected. I tested the voltage on the prop plug when it was not connected to the board, and it read a steady 3.3V. But when plugged into the board, it barely reads 1.5. The Propeller chip itself is drawing all the power, because when I take it off the board the voltage on the prop plug pins goes back to 3.3V.
Any ideas on how to make the LED light? The setup and testing lab doesn't has tons of information for troubleshooting, but none of it seems to help.
Comments
Mike's advice is good, as always. You're probably not going to damage anything by attempting a program download. Plug in the battery, and verify that the power LED glows brightly. Then, plug in the Propeller Plug. If the power LED stays nice and bright, try a program download. The only thing to watch out for would be if the power LED is glowing brightly with the 9 V supply, but gets faint or goes out when the Propeller Plug gets connected. If that happens, disconnect the Propeller Plug immediately and go back to checking your wiring.
Just a four more suggestions:
(1) Make sure you are using v1.1 of the Setup and Testing lab. If not, download it from http://www.parallax.com/detail.asp?product_id=32305.
(2) Double-check to make sure the parts on the Propeller plug are facing up, and the label is facing down. (See Figure 3 in Setup and Testing v1.1.)
(3) Make sure your Propeller chip is well socketed. If it's not properly socketed, the LED might not glow faintly without the battery.· When the pins are all the way into the sockets, the underside of the chip will be flush with the breadboard.
(4) Check the orientation of the Propeller chip and 24LC256 EEPROM. Both of their reference notches should be toward the top of the board. (Figure 3 again)
If the program does successfully download, we'll know the connections were correct, and we'll have to revisit those faint power LED instructions. If you instead get an error message, continue with item 6 in Setup and Testing's Trouble Shooting section.
Please let us know the results either way.
One·unrelated note -·make sure that one end of the 10 k resistor is tied to 3.3 V, and the other to pin 5 of the 24LC256.
Regards, Andy
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Andy Lindsay
Education Department
Parallax, Inc.
Post Edited (Andy Lindsay (Parallax)) : 2/28/2007 5:48:36 AM GMT
Also, the regulators all display the correct voltage on their output pins, but they get fairly hot fairly quick. Is this part of the problem?
The only pins on the whole board that are higher than a volt are the Tx and Rx pins on the plug, and pins 31 and 32 on the Propeller. Everything else has a barely noticeable voltage.
Post Edited (statemachine) : 2/28/2007 12:43:51 PM GMT
setup and we can take a look for something obvious.
Good news was is that the EEPROM survived, but I'm sure that I have made a dramatic impact on it's life expectancy.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
backwards. Because it had been so long since I did soldering work, it took me most of the day to go out and purchase the necessary
desoldering stuff (solder wick, and a spring-loaded solder sucker) which was a pain. I also have a tendency to solder multiple pins of
something too early, before checking it for alignment and so on. Even when I'm doing something simple, like soldering the female
headers on a protoboard so I can breadboard things, I make little errors---in this case I chose the holes further from the processor
(to minimize the heat going into the prop package), but I realize now that's going to be a problem when I hardwire logic onto the
same board (because the other set of holes are now much less accessible, being on the wrong side of the header).
You have to break a few eggs, I guess. So far nothing has actually broken yet (which probably just means I'm not trying hard enough).
Here's something I've done that has helped in the past. Starting with a printout of Figure 3, (or a photocopy of the box sleeve) I'll write down the coordinates of one of the components (chip, wire, resistor, pushbutton, etc). Then, I'll set the figure aside and verify the component coordinates on my board. Then, going back to the figure, I'll draw over that component with a highlighter pen to check it off. The process is similar for the schematic.
Upside-down and backwards chips are quite possibly the problem. The reference notch on the Propeller chip should be in the same location as the one on the sticker, top-center of the chip in Figure 3. Likewise with the 24LC256, the reference notch should also be top-center.
The print on the voltage regulators should be facing to the left as you look at Figure 3, and both metal tabs should be toward the right. The upper-left voltage regulator should be the LM2940-5.0, and the lower-right one should be the LM2937-3.3.
Power to ground mistakes are easy to make, especially in the area around the voltage regulator and EEPROM. All a wire has to be is one row off. Other places where a problem can occur is in the neighborhood of the Propeller chip's GND and 3.3 V connections. One column off on one of the power rails will have the same effect.
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Andy Lindsay
Education Department
Parallax, Inc.
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Andy Lindsay
Education Department
Parallax, Inc.
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Andy Lindsay
Education Department
Parallax, Inc.
mike.popoloski.googlepages.com/images.zip
Here's the first installment of extra trouble-shooting suggestions.
Try removing the EEPROM. Then, connect everything else and load the Program into the Propeller chip with F10. Disconnect power as quickly as possible if it doesn't work.
It's pretty rare, but sometimes a long wire end can snake its way through and make contact with an adjacent row/column. I would examine any wire that seemed to go into the socket too deeply. Also examine wires that are entering the socket at an angle (instead of vertical).
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Andy Lindsay
Education Department
Parallax, Inc.
With USB connection (Propeller plug to 4-pin header to PC USB port) but without 9 V battery:
Power rails (all): 1.88 V (all four)
Propeller Plug RX pin (a-f, 1): 2.27 V
Propeller Plug TX pin (a-f, 2): 2.53 V
Propeller Plug RES pin (a-f, 3) : 0 V (Regardless of whether reset button is pressed)
Propeller Plug Vss pin (a-f, 4) : 0 V
With 9 V Battery connected and Propeller Plug Disconnected:
Power rails: 3.3 V (all)
Propeller Plug RX pin (a-f, 1): 0.03 V
Propeller Plug TX pin (a-f, 2): 0.04 V
Propeller Plug RES pin (a-f, 3) : 3.30 V <0 V when Reset button pressed>
Propeller Plug Vss pin (a-f, 4) : 0 V
With 9 V Battery and Propeller Plug + PC USB connected:
Power rails: 3.3 V (all)
Propeller Plug RX pin (a-f, 1): 3.24 V
Propeller Plug TX pin (a-f, 2): 3.28 V
Propeller Plug RES pin (a-f, 3) : 3.30 V <0 V when Reset button pressed>
Propeller Plug Vss pin (a-f, 4) : 0 V
Regardless of USB connection:
Positive power input (g-l, 1): 6 to 10 V*
GND (g-l, 2 and 4): 0 V
+ 5 V (g-l, 3): 4.99 V
+ 3 V (g-l, 5): 3.3 V
* For best results, use a new alkaline battery, which should be 9+ V.
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Andy Lindsay
Education Department
Parallax, Inc.
Please contact me via email using the envelope icon to the left of this post, and I'll we'll send you another Propeller chip to test.
Thanks, Andy
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Andy Lindsay
Education Department
Parallax, Inc.
I once had a similar problem (over-heating components) when I installed a push-button the wrong way around, but your pic's suggest that's not the case here.
It's intriguing -- please let us know what it was when you've fixed it [noparse];)[/noparse]
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Cheers,
Simon
BTW: I type as I'm thinking, so please don't take any offense at my writing style
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 ;-)