For one-of-a-kind experimenting, what I find cheap and reliable is to
point-to-point soldering, using wire-wrap wire on a board that has sockets
with the usual PC pins, not the long wire-wrap pins. It takes a delicate
touch with the solder iron, but nothing all that tricky. It is no harder to
fix mistakes than unwinding wire-wrap, and the sockets are cheap. In fact,
I've done a few small boards soldering directly to the pins of a DIP IC
stuck
in perf board. Not production stuff, but works just fine.
The last wire-wrap board I did was in circa 1968. We sent a paper-tape to an
outfit and got 25 boards back machine wrapped. (A mess of wiring, but they
worked.)
Donald E Haselwood
MODA problems...again
Started by ●July 9, 2006
Reply by ●July 19, 20062006-07-19
Reply by ●July 19, 20062006-07-19
c...@yahoo.com wrote:
> Unfortunately, after about a month (on and off) of debugging my
> board, I have decided to scrap it and start over. I'm much too
> frustrated with it, and the last time I plugged it in, even the
> BUFFALO login messages are messed up. Sometimes it will report
> perfectly with nothing wrong at all, sometimes it will keep saying
> "BUFFALO 3.2 (int)...." over and over again, and sometimes I get
> nothing. Its hard to think that both the chips I had were faulty, but
> that's what I'm assuming is wrong with the unit. The chip im using,
> 68HC11E1 in a DIP package is nowhere to be
I wouldn't make that assumption. That sounds like either a power
problem, or a reset circuitry problem. I'd guess the former, as you
already seem to have some voltages which need some explaining, like
MODA being high when it should be low. I'd guess an intermittent
short to ground caused by a disconnected ground lead intended to
ground MODA grounding something else which pulls down the power
supply.
> found since it was discontinued a while ago, so I'm kinda out of luck
> here. I have the board still, but I removed all the chips and if I can
> find maybe A8 or something that will fit into the 48 pin DIP socket ive
> got and will still be compatible, I might give it a try again, but I
> have chosen to just start anew. I was also thinking of just getting a
> PLCC wirewrap socket and a new chip, but the sockets are like 12$ +
> shipping, and the PLCC chips are about 8-10$ + shipping, it could end up
> costing me like $30.
Tellya what. I've got chips and sockets both. Make me an offer. The
chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
price on your board. It seems a shame to scrap it when it's probably
really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
you one, you'd put it in, and find that your board still doesn't
work, and I wouldn't want that to happen.
Note that the A series chips has only 256 bytes of internal RAM,
and has one less output compare than the E series chips, which
have 512 bytes of internal RAM.
> At first I was going to prototype my own PCB but I am unexperienced
> in that field, and I figured that it would end up cosing me more in the
> long run. I have my engineering schematic all laid out in OrCAD, but I'm
That's correct, unless you factor in the experience and knowledge
you'll gain. But in pure $$$ you'll do better to buy a board.
> also unexperienced with how to convert it to PCB layout. So I found a
> EVBU HC11E1 board online for 20$ + shipping, I'm waiting for it in the
> mail right now, probably won't get here for awhile since its in Israel.
> Anyway, I'll keep you guys posted, and THANKS again to everyone for
> helping me out.
You're very welcome.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
> Unfortunately, after about a month (on and off) of debugging my
> board, I have decided to scrap it and start over. I'm much too
> frustrated with it, and the last time I plugged it in, even the
> BUFFALO login messages are messed up. Sometimes it will report
> perfectly with nothing wrong at all, sometimes it will keep saying
> "BUFFALO 3.2 (int)...." over and over again, and sometimes I get
> nothing. Its hard to think that both the chips I had were faulty, but
> that's what I'm assuming is wrong with the unit. The chip im using,
> 68HC11E1 in a DIP package is nowhere to be
I wouldn't make that assumption. That sounds like either a power
problem, or a reset circuitry problem. I'd guess the former, as you
already seem to have some voltages which need some explaining, like
MODA being high when it should be low. I'd guess an intermittent
short to ground caused by a disconnected ground lead intended to
ground MODA grounding something else which pulls down the power
supply.
> found since it was discontinued a while ago, so I'm kinda out of luck
> here. I have the board still, but I removed all the chips and if I can
> find maybe A8 or something that will fit into the 48 pin DIP socket ive
> got and will still be compatible, I might give it a try again, but I
> have chosen to just start anew. I was also thinking of just getting a
> PLCC wirewrap socket and a new chip, but the sockets are like 12$ +
> shipping, and the PLCC chips are about 8-10$ + shipping, it could end up
> costing me like $30.
Tellya what. I've got chips and sockets both. Make me an offer. The
chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
price on your board. It seems a shame to scrap it when it's probably
really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
you one, you'd put it in, and find that your board still doesn't
work, and I wouldn't want that to happen.
Note that the A series chips has only 256 bytes of internal RAM,
and has one less output compare than the E series chips, which
have 512 bytes of internal RAM.
> At first I was going to prototype my own PCB but I am unexperienced
> in that field, and I figured that it would end up cosing me more in the
> long run. I have my engineering schematic all laid out in OrCAD, but I'm
That's correct, unless you factor in the experience and knowledge
you'll gain. But in pure $$$ you'll do better to buy a board.
> also unexperienced with how to convert it to PCB layout. So I found a
> EVBU HC11E1 board online for 20$ + shipping, I'm waiting for it in the
> mail right now, probably won't get here for awhile since its in Israel.
> Anyway, I'll keep you guys posted, and THANKS again to everyone for
> helping me out.
You're very welcome.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
Reply by ●July 20, 20062006-07-20
Hmmm, buy your chips and sockets, or sell my board eh?? Sounds like an
interesting offer.
>Tellya what. I've got chips and sockets both. Make me an offer. The
>chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
>price on your board. It seems a shame to scrap it when it's probably
>really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
>you one, you'd put it in, and find that your board still doesn't
>work, and I wouldn't want that to happen.
The specifications of my board are as follows:
- Approximately 5x8 in size, and about 5/8 of the board space is currently used, alot of space for additions.)
- 32K SRAM (all 32K is implemented in this memory map, however there are 8 exhaustively mapped ports, but that could be easily changed since its just wirewrap)
- 32K EEPROM (however the chip is a 1 Mb, so 4 independent pages can be written) I've also got a ZIF socket to match this, so you can swap out EEPROM chips quickly without messing with an extractor or bending pins.
- SCI interface with the MCU via a MAX232CPE level shifter.
- LM7805 regulator (with heatsink) to provide power to the board, 1A protection diode, power headers for +5vdc and GND for later expansion, green LED indicator light.
- 8.000 MHz crystal
- All chips are bypassed using 0.1 uF capacitors, the power supply is bypassed with a 47 uF and a 0.1 uF.
- 8 DIP switches for mode selection, only 2 are used, leaving 6 for expansion.
- Reset circuitry and XIRQ buttons are provided.
- Wirewraps are point-to-point and are taut.
- All chips have been labeled with pin markers on the underside to ensure correct connectivity and to speed debugging and development.
Thats all I can think of for right now, if youre really interested in buying the board, I can post up some pictures of it, and some schematics if you like. If you can make some interesting offer, like trade me for some chips or something, that might work out too. Just out of curiosity, how much would you sell your A8 for, or your PLCC and the A8?
But beware! I have already expressed that fact that the board doesn't work 100%, but if you really wanna try to debug it. Be my guest.
Thanks,
Chuck
>Tellya what. I've got chips and sockets both. Make me an offer. The
>chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
>price on your board. It seems a shame to scrap it when it's probably
>really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
>you one, you'd put it in, and find that your board still doesn't
>work, and I wouldn't want that to happen.
The specifications of my board are as follows:
- Approximately 5x8 in size, and about 5/8 of the board space is currently used, alot of space for additions.)
- 32K SRAM (all 32K is implemented in this memory map, however there are 8 exhaustively mapped ports, but that could be easily changed since its just wirewrap)
- 32K EEPROM (however the chip is a 1 Mb, so 4 independent pages can be written) I've also got a ZIF socket to match this, so you can swap out EEPROM chips quickly without messing with an extractor or bending pins.
- SCI interface with the MCU via a MAX232CPE level shifter.
- LM7805 regulator (with heatsink) to provide power to the board, 1A protection diode, power headers for +5vdc and GND for later expansion, green LED indicator light.
- 8.000 MHz crystal
- All chips are bypassed using 0.1 uF capacitors, the power supply is bypassed with a 47 uF and a 0.1 uF.
- 8 DIP switches for mode selection, only 2 are used, leaving 6 for expansion.
- Reset circuitry and XIRQ buttons are provided.
- Wirewraps are point-to-point and are taut.
- All chips have been labeled with pin markers on the underside to ensure correct connectivity and to speed debugging and development.
Thats all I can think of for right now, if youre really interested in buying the board, I can post up some pictures of it, and some schematics if you like. If you can make some interesting offer, like trade me for some chips or something, that might work out too. Just out of curiosity, how much would you sell your A8 for, or your PLCC and the A8?
But beware! I have already expressed that fact that the board doesn't work 100%, but if you really wanna try to debug it. Be my guest.
Thanks,
Chuck
Reply by ●July 20, 20062006-07-20
c...@yahoo.com wrote:
>
> Hmmm, buy your chips and sockets, or sell my board eh?? Sounds like an interesting offer.
>>Tellya what. I've got chips and sockets both. Make me an offer. The
>>chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
>>price on your board. It seems a shame to scrap it when it's probably
>>really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
>>you one, you'd put it in, and find that your board still doesn't
>>work, and I wouldn't want that to happen.
> The specifications of my board are as follows:
[snip]
> Thats all I can think of for right now, if youre really interested in
> buying the board, I can post up some pictures of it, and some schematics
> if you like. If you can make some interesting offer, like trade me for
> some chips or something, that might work out too. Just out of curiosity,
> how much would you sell your A8 for, or your PLCC and the A8?
I've got something like 100 A8 in PLCC and I have a few tens of sockets.
You quoted prices, I suggested that you make an offer. Concerning the
chips and sockets
The chips are pulls from socketed equipment, and each has
been verified by me personally to boot in all four modes
I have not checked the A/D for accuracy etc. but see no
reason they should not be working properly. Many have
BUFFALO (3.2) on board, and I'd make sure you got one/some
with BUFFALO if that's what you want.
the sockets are new in tubes (though I'd pull the sockets
you want and package them separately)
> But beware! I have already expressed that fact that the board doesn't
> work 100%, but if you really wanna try to debug it. Be my guest.
I wonder if your board isn't worth just about a chip or two and a socket
or two.
It just seems a shame to toss what is a board with almost surely a
simple problem. And it seems a shame that I've got a bunch of chips
which are likely never to be used. At least I'll never build 100 boards.
This probably needs to go to private e-mail, not the group, at this
point, since it's not really a trading post.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
>
> Hmmm, buy your chips and sockets, or sell my board eh?? Sounds like an interesting offer.
>>Tellya what. I've got chips and sockets both. Make me an offer. The
>>chips I have are MC68HC11A8 PLCC and matching sockets. Or, make me
>>price on your board. It seems a shame to scrap it when it's probably
>>really ok. I've also got MC68HC11A8P 48 pin DIP (0.6"), but if I sold
>>you one, you'd put it in, and find that your board still doesn't
>>work, and I wouldn't want that to happen.
> The specifications of my board are as follows:
[snip]
> Thats all I can think of for right now, if youre really interested in
> buying the board, I can post up some pictures of it, and some schematics
> if you like. If you can make some interesting offer, like trade me for
> some chips or something, that might work out too. Just out of curiosity,
> how much would you sell your A8 for, or your PLCC and the A8?
I've got something like 100 A8 in PLCC and I have a few tens of sockets.
You quoted prices, I suggested that you make an offer. Concerning the
chips and sockets
The chips are pulls from socketed equipment, and each has
been verified by me personally to boot in all four modes
I have not checked the A/D for accuracy etc. but see no
reason they should not be working properly. Many have
BUFFALO (3.2) on board, and I'd make sure you got one/some
with BUFFALO if that's what you want.
the sockets are new in tubes (though I'd pull the sockets
you want and package them separately)
> But beware! I have already expressed that fact that the board doesn't
> work 100%, but if you really wanna try to debug it. Be my guest.
I wonder if your board isn't worth just about a chip or two and a socket
or two.
It just seems a shame to toss what is a board with almost surely a
simple problem. And it seems a shame that I've got a bunch of chips
which are likely never to be used. At least I'll never build 100 boards.
This probably needs to go to private e-mail, not the group, at this
point, since it's not really a trading post.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
Reply by ●July 24, 20062006-07-24
Okay, so I've decided to hang on to my existing board for awhile (as per
request of a buddy of mine who helped me with the board's software) and
I've ordered some extra parts that I think might be faulty (and some more
parts to build another board if I need to).
So afer debugging for awhile, I noticed that I've checked and rechecked my wiring, however I did not check the passive components (ie resistors, capacitors, diodes, etc) to see if they were still working. So, while checking the circuitry for the crystal oscillator (8 Mhz), I checked the voltages across the load capacitors (22 pF monolithic, 50 v) and noticed that the voltage across the capacitor connected to EXTAL (pin 29) was 0.0 volts, however the other load cap connected to XTAL (pin 30) was consistently about 4.9 volts.
Is this correct? Could anyone out there pull out their board and do a quick sanity check for me please?
I don't know the specifics of how the cystal oscillator works, I just know that the load capacitance serves to increase the frequency of the crystal. I also don't have access to an oscilloscope, so I wouldn't be able to check the actual waveforms of the crystal or E clock.
I also tried to charge the cap in question to +5vdc and test the voltage across it, but there was nothing, however it doesn't show any symptoms of it being dead. I've also heard that the failure rate for these types of capacitors is quite low, so...
AND, if the oscillator circuit is faulty, it may explain why my mode select doesn't work since the documentation for the HC11 says that the mode select voltages (MODA and MODB) are clock edge trigged and are latched into a status register on reset.
If anyone could tell me if I'm on the right track or not, I'd appreciate it.
Thanks,
Chuck
So afer debugging for awhile, I noticed that I've checked and rechecked my wiring, however I did not check the passive components (ie resistors, capacitors, diodes, etc) to see if they were still working. So, while checking the circuitry for the crystal oscillator (8 Mhz), I checked the voltages across the load capacitors (22 pF monolithic, 50 v) and noticed that the voltage across the capacitor connected to EXTAL (pin 29) was 0.0 volts, however the other load cap connected to XTAL (pin 30) was consistently about 4.9 volts.
Is this correct? Could anyone out there pull out their board and do a quick sanity check for me please?
I don't know the specifics of how the cystal oscillator works, I just know that the load capacitance serves to increase the frequency of the crystal. I also don't have access to an oscilloscope, so I wouldn't be able to check the actual waveforms of the crystal or E clock.
I also tried to charge the cap in question to +5vdc and test the voltage across it, but there was nothing, however it doesn't show any symptoms of it being dead. I've also heard that the failure rate for these types of capacitors is quite low, so...
AND, if the oscillator circuit is faulty, it may explain why my mode select doesn't work since the documentation for the HC11 says that the mode select voltages (MODA and MODB) are clock edge trigged and are latched into a status register on reset.
If anyone could tell me if I'm on the right track or not, I'd appreciate it.
Thanks,
Chuck
Reply by ●July 24, 20062006-07-24
c...@yahoo.com wrote:
> Okay, so I've decided to hang on to my existing board for awhile (as
> per request of a buddy of mine who helped me with the board's software)
> and I've ordered some extra parts that I think might be faulty (and some
> more parts to build another board if I need to).
Good. Troubleshooting this board will help you learn some electronics.
> So afer debugging for awhile, I noticed that I've checked and
> rechecked my wiring, however I did not check the passive components (ie
> resistors, capacitors, diodes, etc) to see if they were still working.
> So, while checking the circuitry for the crystal oscillator (8 Mhz), I
> checked the voltages across the load capacitors (22 pF monolithic, 50 v)
> and noticed that the voltage across the capacitor connected to EXTAL
> (pin 29) was 0.0 volts, however the other load cap connected to XTAL
> (pin 30) was consistently about 4.9 volts.
Placing the probe from an ordinary voltmeter on a crystal is enough
kill most oscillators.
> Is this correct? Could anyone out there pull out their board and do a quick sanity check for me please?
No, it is not. But then, it could be your means of test.
OTOH, if you use a high-impedance DMM, and remove one lead
of the crystal, you should see about 2.5V on the output
(XTAL) pin. This sounds like your feedback resistor (usually
10M to 20M) may have come disconnected, one of your caps may
have shorted, or you may have a cracked crystal.
The feedback resistor is used to bias the CMOS gate into its
linear operating range.
> I don't know the specifics of how the cystal oscillator works, I just
> know that the load capacitance serves to increase the frequency of the
> crystal. I also don't have access to an oscilloscope, so I wouldn't be
> able to check the actual waveforms of the crystal or E clock.
The "load capacitances" provide proper phase shift for oscillation.
They are not for frequency determining, though in the case of
"parallel" operation of the crystal they do have a slight effect
on the frequency of operation.
> I also tried to charge the cap in question to +5vdc and test the
> voltage across it, but there was nothing, however it doesn't show any
> symptoms of it being dead. I've also heard that the failure rate for
> these types of capacitors is quite low, so...
The amount of energy stored in a 20pF cap. at 5V is too minute
to notice with an ordinary voltmeter.
> AND, if the oscillator circuit is faulty, it may explain why my mode select doesn't work since the documentation for the HC11 says that the mode select voltages (MODA and MODB) are clock edge trigged and are latched into a status register on reset.
>
> If anyone could tell me if I'm on the right track or not, I'd appreciate it.
HTH. And, please hit Return about every 60 or 70 characters.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
> Okay, so I've decided to hang on to my existing board for awhile (as
> per request of a buddy of mine who helped me with the board's software)
> and I've ordered some extra parts that I think might be faulty (and some
> more parts to build another board if I need to).
Good. Troubleshooting this board will help you learn some electronics.
> So afer debugging for awhile, I noticed that I've checked and
> rechecked my wiring, however I did not check the passive components (ie
> resistors, capacitors, diodes, etc) to see if they were still working.
> So, while checking the circuitry for the crystal oscillator (8 Mhz), I
> checked the voltages across the load capacitors (22 pF monolithic, 50 v)
> and noticed that the voltage across the capacitor connected to EXTAL
> (pin 29) was 0.0 volts, however the other load cap connected to XTAL
> (pin 30) was consistently about 4.9 volts.
Placing the probe from an ordinary voltmeter on a crystal is enough
kill most oscillators.
> Is this correct? Could anyone out there pull out their board and do a quick sanity check for me please?
No, it is not. But then, it could be your means of test.
OTOH, if you use a high-impedance DMM, and remove one lead
of the crystal, you should see about 2.5V on the output
(XTAL) pin. This sounds like your feedback resistor (usually
10M to 20M) may have come disconnected, one of your caps may
have shorted, or you may have a cracked crystal.
The feedback resistor is used to bias the CMOS gate into its
linear operating range.
> I don't know the specifics of how the cystal oscillator works, I just
> know that the load capacitance serves to increase the frequency of the
> crystal. I also don't have access to an oscilloscope, so I wouldn't be
> able to check the actual waveforms of the crystal or E clock.
The "load capacitances" provide proper phase shift for oscillation.
They are not for frequency determining, though in the case of
"parallel" operation of the crystal they do have a slight effect
on the frequency of operation.
> I also tried to charge the cap in question to +5vdc and test the
> voltage across it, but there was nothing, however it doesn't show any
> symptoms of it being dead. I've also heard that the failure rate for
> these types of capacitors is quite low, so...
The amount of energy stored in a 20pF cap. at 5V is too minute
to notice with an ordinary voltmeter.
> AND, if the oscillator circuit is faulty, it may explain why my mode select doesn't work since the documentation for the HC11 says that the mode select voltages (MODA and MODB) are clock edge trigged and are latched into a status register on reset.
>
> If anyone could tell me if I'm on the right track or not, I'd appreciate it.
HTH. And, please hit Return about every 60 or 70 characters.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
Reply by ●July 25, 20062006-07-25
