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I once again apologize, this is my third (and hopefully final) attempt at trying to learn how to use this yahoo groups forum thing, and I think ive sent out the same message 2 or 3 times.

If ive repeated this information, I again apologize. :)

I've wirewrapped a simple M68HC11 board with 32K external SRAM/EEPROM, and serial port interface. I left it in my car during a road trip over the weekend, and I tested it when I got home, and everything seemed to work fine, until I tried to program the external EEPROM, which I have done many times before the trip. The software I use reports that MODA and MODB are not tied low and the system is not reset. However, when I check the voltages with a voltmeter, I get the following results:

Before Reset
------------
MODA: 3.1 - 3.3 volts
MODB: 4.89 volts
During Reset
------------
MODA: 4.89 volts
MODB: 4.89 volts
After Reset
------------
MODA: 3.1 - 3.3 volts
MODB: 4.89 volts

Also, the board always gets stuck in BUFFALO mode whenever MODB is high, which means that somehow, the MODA pin is stuck at a logic low level??
The pins on my board are connected via a DIP switch with a 4.7K SIP resistor. It doesn't matter if MODA is switched or not, but when I reset whenever MODB is high, the BUFFALO monitor comes up.

Can anyone out there with an o-scope verify that this is correct or incorrect please? Ive checked and rechecked my wiring diagrams, rewired the board several times, and Im about to scrap this thing and just start with a PLCC package. I have been struggling with this board for quite sometime, and I would appreciate any feedback on what I'm doing wrong or what I'm not doing.

THANKS,

Chuck




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Since nobody has answered you yet, I thought I'd comment briefly, off the
top of my head. I'm not familiar with the particular board/circuit design
you are using, but looking at your voltage measurements, I would say that
your software is correct in it's reporting that neither MODA or MODB are
tied low. If they were tied-low, you would see something much more like
0.0 volts on each of them, if the board you use is anything like my
board. I use a board from New Micros.

My board has a pair of jumper-shunts that I install for forcing MODA and
MODB low during reset. It is my thought that if your board was also built
with jumper-shunts involved, that maybe somehow the shunts became
dislodged...maybe while sitting in your car.

As for Buffalo coming up when you boot, I think that is related to whether
a specific pin on one of the ports is tied low or high during bootup. This
is documented somewhere, perhaps in the Buffalo manual. I have so seldom
used Buffalo, that I don't remember the details myself.

Steve

At 03:21 AM 7/9/2006, you wrote:
>...
>
>I've wirewrapped a simple M68HC11 board with 32K external SRAM/EEPROM, and
>serial port interface. I left it in my car during a road trip over the
>weekend, and I tested it when I got home, and everything seemed to work
>fine, until I tried to program the external EEPROM, which I have done many
>times before the trip. The software I use reports that MODA and MODB are
>not tied low and the system is not reset. However, when I check the
>voltages with a voltmeter, I get the following results:
>
>Before Reset
>------------
>MODA: 3.1 - 3.3 volts
>MODB: 4.89 volts
>
>During Reset
>------------
>MODA: 4.89 volts
>MODB: 4.89 volts
>
>After Reset
>------------
>MODA: 3.1 - 3.3 volts
>MODB: 4.89 volts



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c...@yahoo.com wrote:
> I once again apologize, this is my third (and hopefully final) attempt at trying to learn how to use this yahoo groups forum thing, and I think ive sent out the same message 2 or 3 times.

I'd appreciate it if you hit return from time to time.

> If ive repeated this information, I again apologize. :)

> I've wirewrapped a simple M68HC11 board with 32K external
> SRAM/EEPROM, and serial port interface. I left it in my car during a

Wirewrap is not the best choice for a "portable" application.
At just a 2MHz bus, frequency doesn't come into it much, but
most modern stuff operates at frequencies for which wirewrap
is more than just questionable.

I suppose that you mean 32K SRAM and 32K EEPROM. I don't know what
a single device SRAM/EEPROM would be.

> road trip over the weekend, and I tested it when I got home, and
> everything seemed to work fine, until I tried to program the external
> EEPROM, which I have done many times before the trip. The software I
> use reports that MODA and MODB are not tied low and the system is not

Ah, it expects SPECIAL BOOTSTRAP mode. I've been trying to sort through
all this, and you present a bunch of information all spread out,
and we're having to piece things together. See below...

> reset. However, when I check the voltages with a voltmeter, I get
> the following results:

Do you have a socketed chip? Try checking the voltages on
the chip pins, not the socket pins. Also, carefully inspect
all the wirewrap sockets for bent pins. Those long wirewrap
pins are very susceptible to being bent and shorting.

> Before Reset
> ------------
> MODA: 3.1 - 3.3 volts

This is a "high", but it is suspiciously "low".
Hmm... LIR? I bet that you are not using a 'scope.

> MODB: 4.89 volts

So is this. What is your power supply providing?
If it provides 4.89V then what you show here looks
not too bad.

> During Reset
> ------------
> MODA: 4.89 volts
> MODB: 4.89 volts

This is selecting SINGLE CHIP mode.

[snip]

> Also, the board always gets stuck in BUFFALO mode whenever MODB is
> high, which means that somehow, the MODA pin is stuck at a logic low
> level??

This sounds like you have BUFFALO on the chip ROM itself. When the
chip is in SINGLE CHIP mode, it ignores the ROMON bit, and forces
the internal ROM to be enabled. If this is BUFFALO, then that's
what you get. Does the signon have "(int)" in it? If so, then this
is an internal version of BUFFALO. External versions are supposed
to display "(ext)" in the signon message.

> The pins on my board are connected via a DIP switch with a 4.7K SIP
> resistor. It doesn't matter if MODA is switched or not, but when I reset
> whenever MODB is high, the BUFFALO monitor comes up.

Ok, MODB selects between NORMAL/SPECIAL modes. MODA selects between
SINGLE/EXPANDED modes. It sounds like MODA is stuck "low" and you are
always booting to SINGLE CHIP mode, and the internal BUFFALO is
coming up.

> Can anyone out there with an o-scope verify that this is correct or
> incorrect please? Ive checked and rechecked my wiring diagrams, rewired

How can we check your board?

> the board several times, and Im about to scrap this thing and just start
> with a PLCC package. I have been struggling with this board for quite
> sometime, and I would appreciate any feedback on what I'm doing wrong or
> what I'm not doing.

Oh, it's not the PLCC package. You are using the MC68HC11A8P version.

Ok, here's what I glean.

You are using an MC68HC11A8P version in a wirewrap socket.

You are using software to communicate via the SCI port. This
software expects the chip to be booted in SPECIAL BOOT mode.
(PCBUG?)

MODA and MODB go to jumpers or DIP switches or the like through
4.7K SIP resistor pack. Hmm, no this isn't right. Or is it?
Circuit might be
4.7K
+5 o----------/\/\/\---------+--------o MODA
|
o
o(switch/jumper)
|
---
///

or it might be

+5 o---------o 4.7K
o--/\/\----------o MODA
GND o---------o(switch/jumper)
In the first case, it sounds like your switch or jumper is
defective, or you have lost your ground connection to the
jumper/switch.

In the second case, it sounds like you have a
short between the resistor and +5.
The second circuit is the better one, BTW.

You don't specify whether the voltages on MODB change when
you move the jumper/switch. It's possible that you have
the first circuit, and you have lost the ground connection
to the mode selection circuitry altogether. This seems likely
to me based on your statement that you used a SIP resistor
pack. In that case, it would guess that you have a common
point tied to +5 as pull-ups, and jumpers/switches as
pull downs on the pins themselves.

Anyway, your problem seems to be that MODA is not getting
grounded. Check all your wirewrap posts for being bent.
Check your MODA circuit switches/jumpers for proper operation.

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!



(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

THANKS STEVE and MIKE for helping me out thus far...your comments are very much appreciated!!!
To Steve:
The board that I am using is a handmade board using DIP chip packages and wirewrap.

To Mike:
Sorry since my last posts were a bit unclear, I was getting frustrated with the forms on the forum getting cleared accidentally. The board that I am using is a lab project from last Spring, not meant to be used for any commercial or portable applications. I am aware of the high-freq. limitations of wirewrap, however I simply used wirewrap for this board because I have no other alternatives at the moment. I am using this board for some simple tinkering and other development I plan on doing later (given that I can get it working).

About the, "32K external SRAM/EEPROM" comment, I again apologize if this was unclear, but yes I meant separately 32K SRAM and 32K EEPROM.

Yes, the chips are socketed. As soon as I get a chance I'll take a look at the alignment of the pins and the chip pin voltages. I don't have access to a scope at the moment unfortunately, but If I can get my hands on one I'll check it out.

I'm using a simple 7805 +5vdc regulator for this design, and I have this chip coupled with 2 bypass capacitors.

The software I am using (and have used successfully in the past before) is a TTERM script that a friend of mine developed for these generic type HC11 boards. From what I know, his code is uploaded to the internal EEPROM of the HC11 in SPECIAL BOOTSTRAP mode. This progam then sends an *.s19 file via SCI to be programmed into the external EEPROM.

So my schematic for switching between hardware modes looks kind of like this:

- Note: 4.7K resistor in SIP package with common pin connected to +5vdc

+5vdc-------/\/\/\-----o DIP switch o---------GND
|
|
|
MODA Pin

And the same goes for the MODB Pin.
My MODB pin works at 5vdc (or very close to 5vdc) with the switch open and a solid 0.0vdc with the switch closed. BUT, when my MODA pin switch is open, I get a wierd 3.1-3.3vdc. However, when I close the switch, it gets a solid 0.0vdc also. So technically, my MODA pin only works for modes with a logic 0 associated with it, IE bootstrap and single chip mode.

When powering up the board with MODB high, it seems that my MODA pin is always recognized as low. So I'll always get the BUFFALO mode. I've just checked it again just now, and it says "(int)" in the signon.

Yes the voltages change when I move the switches. But see, its weird because when I move the switches without resetting, I get solid logic levels for each pin, but after reset, the MODA pin is 3.1-3.3vdc. (Probably because of the fast switching that my multimeter can't pick up when the MODA pin goes to LIR.) Also, I changed the resistor pack and the DIP switches, thinking that they were faulty. But it did not resolve the issue.

I know the DIP package for the HC11 is obsolete, however at this point, I have no choice. Also, I am using the E1 DIP not the A8P series of the chip, if that makes any difference.

I'll check for bent wirewrap pins, loose grounding, and correct switch operation.

Thanks again for the information! It gave me some new insight on what I need to check to make this thing work. (HOPEFULLY!) If anyone else could contribute, I would totally appreciate any input!!

Chuck




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NOTICE!!! Sorry, but when I posted the last thing I accidently had a schematic that looked like this:
+5vdc-------/\/\/\-----o DIP switch o---------GND
|
|
|
MODA Pin

but its actually this:

+5vdc-------/\/\/\-----o DIP switch o---------GND
|
|
|
MODA Pin

I'm no good at ASCII schematics. :)

Chuck




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c...@yahoo.com wrote:
> THANKS STEVE and MIKE for helping me out thus far...your comments are very much appreciated!!!

Very welcome.

> To Steve:
> The board that I am using is a handmade board using DIP chip packages and wirewrap.
>
> To Mike:
> Sorry since my last posts were a bit unclear, I was getting
> frustrated

Understandable, and no problem, except for trying to
figure out how to help.

[snip]

> because I have no other alternatives at the moment. I am using this
> board for some simple tinkering and other development I plan on doing
> later (given that I can get it working).

I wasn't trying to criticize, and this is what I had gathered.
What I was trying to state was that if you are going to transport
a wirewrap board, then you can expect to see this kind of thing
happen again.

[snip]

> I'm using a simple 7805 +5vdc regulator for this design, and I have this chip coupled with 2 bypass capacitors.

Then 4.89V looks ok. The TI book specifies 4.8V to 5.2V.

[snip]

> So my schematic for switching between hardware modes looks kind of like this:
>
> - Note: 4.7K resistor in SIP package with common pin connected to +5vdc
>
> +5vdc-------/\/\/\-----o DIP switch o---------GND
> |
> |
> |
> MODA Pin
>
> And the same goes for the MODB Pin.

Ok, then your symptoms are consistent with loss of ground
connection to the DIP switch, or with a defective DIP switch.

> My MODB pin works at 5vdc (or very close to 5vdc) with the switch
> open
> and a solid 0.0vdc with the switch closed. BUT, when my MODA pin switch
> is open, I get a wierd 3.1-3.3vdc. However, when I close the switch, it

This is not weird. You need to investigate what MODA actually is.
During RESET it is an input, but during normal operation it is
an open drain output, LIR.

> gets a solid 0.0vdc also. So technically, my MODA pin only works for
> modes with a logic 0 associated with it, IE bootstrap and single chip mode.

Eh? You just said that you get 3.1-3.3V on MODA, and now you say it
is solid 0.0V. Which is it? Your software apparently wants SPECIAL
BOOTSTRAP MODE, which requirs MODA = 0V, and MODB = 5V during
RESET. Your earlier message stated that you observed 4.89V on
both MODA and MODB during RESET.

> When powering up the board with MODB high, it seems that my MODA pin
> is always recognized as low. So I'll always get the BUFFALO mode. I've
> just checked it again just now, and it says "(int)" in the signon.

Ok, then you are booting into SINGLE CHIP MODE. That means that, during
RESET, MODA = HIGH and MODB = HIGH, which is consistent with your
earlier message.

> Yes the voltages change when I move the switches. But see, its weird
> because when I move the switches without resetting, I get solid logic
> levels for each pin, but after reset, the MODA pin is 3.1-3.3vdc.
> (Probably because of the fast switching that my multimeter can't pick
> up when the MODA pin goes to LIR.) Also, I changed the resistor pack

Exactly, not weird at all.

> and the DIP switches, thinking that they were faulty. But it did not
> resolve the issue.

During RESET, you stated that MODA = 4.89V, which is high.

> I know the DIP package for the HC11 is obsolete, however at this
> point, I have no choice. Also, I am using the E1 DIP not the A8P series
> of the chip, if that makes any difference.

Not a problem for me. I have four of the A8P, two of which are XC68HC11,
not MC68HC11, so you see how *I* stand!

> I'll check for bent wirewrap pins, loose grounding, and correct switch operation.
>
> Thanks again for the information! It gave me some new insight on what I need to check to make this thing work. (HOPEFULLY!) If anyone else could contribute, I would totally appreciate any input!!

Good luck! And find that RETURN key!

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!




(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

DAMN this thing, that last post I made about my MODA/MODB pin switch schematic was wrong again.

OK, last time :)...

So I had a post that had two of these:

+5vdc-------/\/\/\-----o DIP switch o---------GND
|
|
|
MODA Pin

let me redraw it right....this forum doesnt like spaces in ASCII art...

+5vdc
|
|
|
4.7k
RESISTOR
|
MODA PIN
|
o

DIP SWITCH

o
|
|
___
\\\ (GND)

Ok so more more thing, in table 2-1 of the big HC11 reference manual revision 6, page 47, bootstrap mode is MODA = 0 and MODB = 0.

(FOr the E series chips)

MODB = 0, MODA = 0 : Special Bootstrap
MODB = 0, MODA = 1 : Special Test
MODB = 1, MODA = 0 : Normal Single Chip
MODB = 1, MODA = 1 : Normal Expanded

Chuck





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c...@yahoo.com wrote:
> DAMN this thing, that last post I made about my MODA/MODB pin switch schematic was wrong again.
>
> OK, last time :)...
>
> So I had a post that had two of these:

That's ok, we figured it out. One of them was ok, anyway.

[snip]

> Ok so more more thing, in table 2-1 of the big HC11 reference manual
> revision 6, page 47, bootstrap mode is MODA = 0 and MODB = 0.

Yes. Your table is correct for all families of the '11.

[snippity doo-dah]

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!




(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

c...@yahoo.com wrote:
> THANKS STEVE and MIKE for helping me out thus far...your comments are very much appreciated!!!

How did this come out?

[snip]

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!




(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

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 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.

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 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 need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

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




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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!



(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

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





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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
--
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This message made from 100% recycled bits.
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______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


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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





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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!



(You need to be a member of m68hc11 -- send a blank email to m68hc11-subscribe@yahoogroups.com )

HI everyone,

Could any one of you say me about
TRAFFIC SIGNAL LIGHT TESTER. I hadn't even heard this before.

Regards,
Selva.

---------------------------------
Find out what India is talking about on Yahoo! Answers India.

[Non-text portions of this message have been removed]





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