PIC-EL Kit
Online Assembly / Test Manual

 

Fully-detailed instructions for assembly and test of the PIC-EL Kit.

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Section 14: TROUBLESHOOTING

Perhaps the best way for us to handle this subject is to list the various problems experienced by the initial round of PIC-EL builders, along with the corresponding guidance provided by the design team.  Look over the Topics listed below to see if your specific problem is close to any of the described situations. If none of the guidance is applicable, or if you tried the solution and it didn't work, please feel free to contact us and we'll do our best to help you out.

PIC-EL Support Team:  
    George Heron N2APB - project manager - n2apb@amqrp.org 
    Craig Johnson AA0ZZ - designer - cbjohns@cbjohns.com 


TOPIC 1: PB1 Pushbutton Test Fails and LED1 is ON all the time.

"The PB1 push button test failed because the light was on continuously. The pull up for the input was not high enough with the counter amp load on it. But when I removed the jumper, it was OK."

Yes, it does that.  This is one of those interactions that we ran into when we tried to multiple functions on the small number of pins that are available. That's why we had to put the header in the Counter line - to keep the counter driver disconnected in most cases.  The Assembly manual notes to keep the shunt off the two pins of HDR3, but some guys have it fully installed when starting the Test Program, which will cause the problem you note.


TOPIC 2: Paddle test operates LED1 and LED3, not 1 & 2.

"During the paddle test the dits and dahs operated LED1 and LED3 whereas I was expecting LED1 and LED2.   LED2 was on continuously during the paddle test phase. Is this OK?"

Yes, that's correct.  It just happens to be the way John programmed the test program to work. By the way, the paddles are also connected to the same pins as PB1 and PB2, so you could actually send CW with those two pushbuttons instead of paddles. Don't try this when you are the FOX !  It may be tiresome.


TOPIC 3: Speaker Problems

Here's an important caution to PIC-EL builders ... be very careful not to overheat the leads for speaker SPKR when attaching it to the pc board. The plastic body of this part is really thin and has a low melting point, so if the pads are heated for an extended amount of time there's a good chance the speaker body will "sink onto" the leads on the inside, thus losing electrical connection with the internal speaker element. This would be especially true if you are pushing the device down while soldering the leads to the pad.  It would be *really* true if you are trying to remove the speaker for some reason by pulling the device while heating the pads.

We only have a handful of extra speakers and cannot replace or even sell them to those who request it.  Sorry.  We only had 500 of these nifty little speakers, which was thought to be enough when we started the project.  We had no idea the PIC-EL response and excitement would be as great as it is. We're going to another part (Digi-Key 433-1020-ND) for the next round and we can make extras available from this next batch within a couple of weeks if yours goes south. 

A makeshift speaker to use during the interim can be most any mini "real" speaker, such as from an old modem card, telephone or even a 2" speaker from a kid's walkie talkie.  A "piezo" device than many of us are familiar with won't have the frequency response that a speaker has, so you'd only be able to hear beeps made at about 4 kHz.


TOPIC 4: Assembly Guidance - Resistors

For those that haven't scratch built something before, TAKE YOUR TIME. Those 1/8 watt resistors are hard to read if your eyes are getting old like mine. Even with a magnifying glass, I got the digital meter out and measured the resistors to double check my eyes.  Paid off too, I caught myself thinking I had a 3.3K resistor when in fact I had a 330 ohm one.  


TOPIC 5: Assembly Guidance - Mounting the DDS Card and connector

"The only thing I didn't like was the means for connecting the DDS Daughtercard to the board. You have to either sit it at an angle, or solder stiff wire between the socket pins and the main board.  If you have the 3/8" tall 2-56 standoffs I happened to have only 2 of in the junque box, you can mount the board solid and make it much easier.  Otherwise, it may be a problem.  This board really should be mounted solid if at all possible."

Yes, without a long-pin, right angle socket connector for J6, there's no real elegant way to mount the DDS Daughtercard in its optimal position parallel to the main board and elevated about 3/8".  Connectors couldn't be found ... until right now.  The AmQRP is obtaining a bunch of the ideally-sized right angle connectors and will soon have them available for new kits going out the door.  We'll also provide them at cost to those PIC-EL owners wishing to have a prettier connector on their DDS daughtercard.


TOPIC 6: Use Standoffs for Secure Mounting of LCD and DDS Cards

The earlier kits contain a white reinforced pinheader (P4) for the LCD, and the card is held well in place with just this arrangement. Later kits do not have this reinforced pinheader and the LCD may benefit from being held rigidly in place by using standoffs in the holes provided. If you  happen to have some 4-40 threaded standoffs of the right height, you can use them to firmly fasten the LCD to the board.  You can also mechanically improve your PIC-EL board by making your own standoffs for the DDS Daughtercard by using a couple of 2-56 by 3/4" screws and six 2-56 nuts.  Use 2 of the nuts to mount the screws to the board, leaving them stick up.  Use 2 more nuts to set the desired height above the chassis (about 3/8 to 1/2") and lock the board down with 2 more nuts.  Adjust them so that the DDS board looks level.  Then put the socket on the DDS Card pins and now you can solder the wires between the pins and the main board.  Use the stiffest wire you can find - some old 1 watt resistors in values that you'll never use come in handy for this. Cut the leads from the resistors to use for the wires.  Nice and stiff, and they don't look to bad in the finished version either.

Lowe's had some nice nylon spacers that, in conjunction with some appropriate 4-40 screws, made for a nice way of mechanically holding down the LCD.  These are probably a little more available than the threaded standoffs, although not nearly as nice.  The same could be done for the LCD, but with 14 pins holding up the little display card, not much improvement is needed.


TOPIC 7: Go Through Lesson 10 Before Installing Serial Connector J2

It may be helpful if you delay mounting the RS-232 connector until you get halfway through Lesson 10.  The reason for this is that in the beginning of Lesson 10, you want to hang your voltmeter on the RS-232 pins.  These things are a bear to grab, but if you plug the connector in, it's no problem.  Once you have the connector soldered into the PIC-EL, you can no longer reach the pins with your probe. If you have a spare RS-232 connector laying around then you can use that just as well.


TOPIC 8: Using a ZIF Socket for the PIC

If all goes well in building the PIC-EL, the Elmer 160 students should never need to remove the PIC.  I've had mine in place on my prototype PIC-EL board since early December, and it's been through maybe 200 re-programming cycles.

But if you use the PIC-EL as a programmer board for a PIC destined for use in another project application, you'll frequently be removing and inserting PICs to the socket.  In this case, you might want to find yourself a ZIF (zero insertion force) socket to save wear & tear on the board and socket supplied as stock with the kit.

To fit a 20-pin ZIF in the 18-hole slot left by the "removed" IC socket, first relocate C9 and R30 to the bottom of the board. You may need to re-form (bend) the lever on the ZIF to clear other parts on the board.

Jim Sheldon, W0EB tells us:  "I saw a post by someone looking for an inexpensive ZIF socket (18 pin) that would fit the PIC-EL board.  I did a google search on "zif socket" and after checking several sites, I ordered myself one from a company called Futurlec. They have an 18 pin standard ZIF socket available that should fit the board for $4.00 each in quantities of 1 and their shipping/handling is only $3.00 for ground.  Not bad and no minimum order.  I placed an order with them and got immediate email confirmation of receipt of order.  Now we'll see how they shape up.   Usual disclaimer applies, I had never even heard of them before doing this search, so I'm going to be the guinea pig.  Anyone interested can check 'em out at http://www.futurlec.com/Sockets/ZIFS18.shtml ".


TOPIC 9: Problems after Programming my first PIC

"Here's my starting point:  PIC-EL built and passes all tests in Lesson 10. Downloaded T-Pickel.ZIP.  Loaded T-PICEL.hex. Can read and verify PIC. No DDS daughter PCB. After power-up, no display on LCD, LED1 never turns on, LED2 and LED3 go on and off, SPKR burps and then eventually plays a scale, I observe no response from pressing PBs, and observe no response from encoder.  Help!"

I would look hard at that LED1 line.  If you notice, it's shared with LCD data, and if you can't get the LCD initialized then the encoder test will be a flop, too.  However, I would expect buttons 2 and 3 to work.

Here's the deal, though.  It's tough without the LCD. When you power up, the LCD displays a banner that takes a few seconds.  Then there's a little chirp, and it should blink the LEDs for about 15 seconds. Then another chirp, and it's about 15 seconds of the button test.  It's only in this second 15 second slot that the buttons should be responsive.  During this time, if you press PB1, LED1 should light, PB2, LED2 etc.  At this point, it's possible that RB3 (LED1/LCD DB7/DDS DATA) is your only problem.

Besides checking for shorts/solder bridges (don't forget that the trace goes all the way over to the DDS socket) check to be sure you didn't fold the PIC pin under in the socket.  I would also check for continuity from PIC pin 9 to LCD pin 14.

Another worthwhile test would be to remove the PIC and power up the board. Then ground pin 9 of the PIC socket.  That should cause LED1 to illuminate. Hopefully this will give you some clues.


TOPIC 10: Using Linux with the PIC-EL board

From Rich Mulvey (rich@mulveyfamily.com) ... "For those of us who prefer to use Linux, instead of Windows, there are a variety of tools you can use for learning to use the PIC in the Elmer 160 course.  http://www.gnupic.org/  has links to many of these tools.  I've been
using gpsim to simulate the exercises, and gpasm to assemble them.  (gpasm is compatable with the Microchip assembler, and I haven't had to make any changes, so far. ;-) )  Now that I have the PIC-EL completed, I'm going to look around for a compatible programmer.

Also, for additional resourced, I picked up a copy of "Programming and customizing PICMicro microcontrollers", by Myke Predko, and it seems like a very good into about how to interface to all sorts of different devices like keyboards, LCD's, etc, do serial port handling, etc.  The book however, is $15.00 more than the PIC-EL.  ;-)


TOPIC 11: Display jumps multiple numbers in Encoder Test

"For Test 5 (Encoder) the display does show incrementing and decrementing, but by twos if the control is turned from one detent to the next. To inc/decrement by ones I have to get "in between" the detents. It will also occasionally jump multiple values, or not respond at all  to rapid rotations. Am I correct in suspecting that this test program doesn't do much debouncing?"

The "erratic" changing of the displayed values when the encoder shaft is turned is a normal situation in our test program. The intention of the Test Program is to ensure that the various components on the board are working, and here it ensures that turning the encoder results in its two signals moving and being read by the PIC. The test program uses only the bare minimum of code and logic to do this, whereas in a full-blown software program that actually uses the encoder to control something (like in the VFO program PEgen, also supplied on the website), other techniques are used to obtain debounce the switch closures, resulting in a nice smooth-incrementing encoder-display combination.  For an example of this extra logic and smooth encoder operation, see the PEgen VFO software provided by Craig AA0ZZ for the PIC-EL board.

Cla KA0GKC says to try this mod to remove the encoder detent ... "As must of you are aware the pickle encoder seems to count 4 for every detent.  The solution is to remove the detent. Warning: This may destroy your encoder.  You are on your own. The hardest part of this mod is removing the encoder if you've already soldered it in. :-(  With the shaft of the encoder facing down, make sure that both mounting tabs are bent slightly to the outside.  With a very small flat blade screwdriver carefully pry up the four metal tabs on the bottom of the encoder.  Lift the black plastic housing off and set aside. (A quick look on the inside of the housing and the end of the shaft will reveal how simple this encoder is.)  Lift the shaft up and out of the metal housing.  See the copper colored square piece?  This is the detent spring.  Remove and discard it. Reassemble the encoder and use a small needle nose the press the four metals tabs back down.  Re-straighten the mounting tabs and install it back in the Pic-El board. Put a nice sized knob on the encoder shaft and you should be able to see nice smooth single counts. YMMV!"


TOPIC 12: Q5 and Speaker getting pretty warm

Just a reminder to PIC-EL builders that transistor Q5 and the speaker will get warm when using the initial version of software that came pre-programmed the PIC supplied in the kit. Although not an ideal condition, it won't hurt anything.  In the Test software downloadable from the website now for some time, we changed the "at-rest" condition of the PIC I/O bit from being a logic HI (which would turn on Q5 and have current going through the speaker), to a logic LO which keeps Q5 turned off. One of the first things we expected guys to do in testing out the programmer portion of the board was to download the updated Test program and burn the new software into the PIC, thus correcting this condition.

So do indeed download and use the latest T-PICEL test program located on the project page at http://www.amqrp.org/elmer160/board/manual/manual.html


Check back often, as we regularly update this page with hints, kinks and ideas that homebrewers might like to try with their PIC-EL.

 

 

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Page last updated:  Feb 10, 2004