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Thread

Connecting to 332

2003-06-18 by Shyam mali

Hi All, 
I have some problems with my first 332 project. 

1. I am having an intermittent problem connecting to the 332 using the SDS debugger (BDM-wiggler cable) on a prototype derived from a working 68332 based target board; same clock, same memory configuration.

After working with the debugger for a few days, my prototype board started having problems with the connection. SDS began giving connection errors ( cannot FREEZE ) on some of the connection attempts and loading incorrect memory values into RAM on others. 

I started looking at the pins and found a waveform on the reset pin when the BDM is not connected. The signal is low and then starts to rise, it reaches up to 0 .4Vdd and then is pulled low again. Looks like a spiked waveform with the signal low for approximately 160ms. This continues until I try to connect to the 332 using BDM port. ( probably random code is being executed until an illegal instruction or memory access occurs forcing the CPU to reset. ) Once in a while the spikes stop to toggle from low to high and then I can connect. If the waveform continues the debugger fails to connect. 

2. I get read verify error at some memory locations. My RAM is configured to start at base address of 0x800000. 

Kindly advise. 
Shyam Mali 




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Re: [68300] Connecting to 332

2003-06-18 by Scott Newell

>I started looking at the pins and found a waveform on the reset pin when the
>BDM is not connected. The signal is low and then starts to rise, it reaches
>up to 0 .4Vdd and then is pulled low again. Looks like a spiked waveform
>with the signal low for approximately 160ms.

What's the value of the pullup resistor on the reset pin?


newell

RE: [68300] Connecting to 332

2003-06-18 by Melear Charles-rdph40

Scott,
 
I have seen the exact waveform you are describing.  Here is how a Power ON Reset sequence works.
 
1.  Reset is asserted low from the application of power.
2. Reset remains low until the SLOCK bit is set in the Clock Synthesizer Control Register.
3. Reset has a 2 system clock cycle period where it goes into a 3-state condition.
4. Reset is then asserted (as an output) to a logic 0 for 512 clock cycles.
5. At the end of the 512 clock cycles, the reset pin enters a 3-state condition for 10 system clock cycles.  If by the end of the 8th clock cycle, the reset pin has reached a logic 1, the reset pin becomes an input (at the end of the 10th cycle).
6.  The reset remains an input and program execution starts.
 
However, if the reset pin has not reached a logic 1 by the end of the 8th or 9th cycle, the internal control circuitry asserts the reset pin to a logic 0 for 512 cycles.
 
Then, go back to step 5 above.
 
I think that what you are seeing is that you have NO pull up resistor on RESET.  The "rise" that you are seeing is the reset pin floating during the 10 cycle period mentioned in step 5 above.
 
Put a 2 Kohm pull up on RESET and I think all your problems will go away.
 
Charlie

Show quoted textHide quoted text

-----Original Message-----
From: Scott Newell [mailto:newell@...]
Sent: Wednesday, June 18, 2003 2:25 PM
To: 68300@yahoogroups.com
Subject: Re: [68300] Connecting to 332


>I started looking at the pins and found a waveform on the reset pin when the
>BDM is not connected. The signal is low and then starts to rise, it reaches
>up to 0 .4Vdd and then is pulled low again. Looks like a spiked waveform
>with the signal low for approximately 160ms.

What's the value of the pullup resistor on the reset pin?


newell



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RE: [68300] Connecting to 332

2003-06-18 by Scott Newell

At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:

>Scott,
>I have seen the exact waveform you are describing.  Here is how a
>Power ON Reset sequence works.

Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
the original poster.  

I'm betting on the missing reset line pullup too.

newell

RE: [68300] Connecting to 332

2003-06-19 by Allen Nance

Shyam:

I had the same type of problem when I tried to add some filtering to the 
reset line.
The most capacitance I could add was .001uF. Otherwise the reset line came 
up too slow
and the scenario that Charlie described earlier would occur.

Allen




At 06:15 PM 6/18/2003 -0500, you wrote:

Show quoted textHide quoted text

>At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:
>
> >Scott,
> >I have seen the exact waveform you are describing.  Here is how a
> >Power ON Reset sequence works.
>
>Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
>the original poster.
>
>I'm betting on the missing reset line pullup too.
>
>
>newell
>
>
>
>
>---------------------------------------------------
>To unsubscribe from this group, send an email to:
>68300-unsubscribe@yahoogroups.com
>
>To learn more about Motorola Microcontrollers, please visit
>http://www.motorola.com/mcu
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

RE: [68300] Connecting to 332

2003-06-19 by Shyam mali

The reset line of the 332 is tied to the MAX707 through a 4k7 series resistor. The design is proven, this board ain't. I tried second board of the same batch and it indicated the same problem. then i isolated all the pins (pulled up the reset and halt pin(which are shorted in my circuit) and observed the waveform... it was the same.
Shyam

--

Show quoted textHide quoted text

--------- Original Message ---------

DATE: Wed, 18 Jun 2003 18:15:41
From: Scott Newell <newell@...>
To: 68300@yahoogroups.com
Cc: 

>At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:
>
>>Scott,
>>I have seen the exact waveform you are describing.  Here is how a
>>Power ON Reset sequence works.
>
>Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
>the original poster.  
>
>I'm betting on the missing reset line pullup too.
> 
>
>newell
>
>
>



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RE: [68300] Connecting to 332

2003-06-19 by Melear Charles-rdph40

Hello everyone,
 
The reset pin of the 683xx family is not really made to be driven by a totem-pole type driver that is used by the Maxim part you mentioned.  What you need to do is use an OPEN COLLECTOR Low Voltage Chip to drive the 68322's reset pin.  You also need a 2 Kohm (or stronger) pull-up resistor on the RESET pin.
 
IF YOU DO NOT HAVE A VERY STRONG PULL UP ON RESET YOUR CIRCUIT WILL NOT WORK!!!!!!!!!!!!!!!!!
 
IF YOU DRIVE THE RESET PIN OF THE 68332 WITH A TOTEM POLE DRIVER (AS OPPOSED TO AN OPEN COLLECTOR DRIVER) YOUR CIRCUIT WILL BE MARGINAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
I have seen people use a totem pole driver (even Maximum's parts) and they use about a 5 Khom resistor (as I recall) between the output of the LVI chip and the 68332 RESET line.
 
The whole problem that is being described here is that the LVI chip is NOT driving the RESET pin of the 68332 high fast enough.  Remember, the RESET pin of the 68332 is an output when the 68332 is asserting reset.  This makes the LVI chip FIGHT the 68332.  Not a good thing.  
 
If you want to send me a copy of the schematic that just shows the reset circuitry, I'll take a look at it.
 
Regards,
 
Charlie

Show quoted textHide quoted text

-----Original Message-----
From: Shyam mali [mailto:sscomputers2@...]
Sent: Thursday, June 19, 2003 8:18 AM
To: 68300@yahoogroups.com
Subject: RE: [68300] Connecting to 332

The reset line of the 332 is tied to the MAX707 through a 4k7 series resistor. The design is proven, this board ain't. I tried second board of the same batch and it indicated the same problem. then i isolated all the pins (pulled up the reset and halt pin(which are shorted in my circuit) and observed the waveform... it was the same.
Shyam

--

--------- Original Message ---------

DATE: Wed, 18 Jun 2003 18:15:41
From: Scott Newell <newell@...>
To: 68300@yahoogroups.com
Cc: 

>At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:
>
>>Scott,
>>I have seen the exact waveform you are describing.  Here is how a
>>Power ON Reset sequence works.
>
>Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
>the original poster.  
>
>I'm betting on the missing reset line pullup too.
> 
>
>newell
>
>
>

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RE: [68300] Connecting to 332

2003-06-19 by Melear Charles-rdph40

Newell,
 
10 - 4.  I posted another message whinning about the pull-up.  As I say, no pull up  --  no work.
 
If the original poster of the message about the reset wave form wants to contact me, send me a private email at charles.melear@... <mailto:charles.melear@...>  and I'll visit with you personally on this issue.  I've seen it before and the fix is ultra easy.
 
Regards,
 
Charlie

Show quoted textHide quoted text

-----Original Message-----
From: Scott Newell [mailto:newell@...]
Sent: Wednesday, June 18, 2003 6:16 PM
To: 68300@yahoogroups.com
Subject: RE: [68300] Connecting to 332


At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:

>Scott,
>I have seen the exact waveform you are describing.  Here is how a
>Power ON Reset sequence works.

Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
the original poster.  

I'm betting on the missing reset line pullup too.


newell




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RE: [68300] Connecting to 332

2003-06-19 by Godiska, Jim

Hello all,
 
I just have three notes for those interested in the 683xx reset.
 
1.  The manuals for this family (or at least the 68376 that I use) recommend
a pullup resistor of 820 ohms.
 
2.  Most reset chips or supervisors (that I found anyway) do not recommend
this low of a resistance (820 ohms) for reset lines.  They cannot handle the
current draw.
 
3.  On my board I use a MAX813L to drive an NPN BJT transistor, which then
uses the 820 ohm pullup resistor for the reset.  I made the mistake once of
using a FET (instead of the BJT) and got burned because of the output
capacitance of the FET (about 220 pF as I recall) and the fact that I use a
20 MHz clock oscillator IC to directly feed the chip (not the internal PLL).
 
Hope this helps.
 
Good luck.
 
Jim

Show quoted textHide quoted text

-----Original Message-----
From: Melear Charles-rdph40 [mailto:charles.melear@...]
Sent: Thursday, June 19, 2003 9:41 AM
To: '68300@yahoogroups.com'
Subject: RE: [68300] Connecting to 332

Hello everyone,

The reset pin of the 683xx family is not really made to be driven by a
totem-pole type driver that is used by the Maxim part you mentioned.  What
you need to do is use an OPEN COLLECTOR Low Voltage Chip to drive the
68322's reset pin.  You also need a 2 Kohm (or stronger) pull-up resistor on
the RESET pin.

IF YOU DO NOT HAVE A VERY STRONG PULL UP ON RESET YOUR CIRCUIT WILL NOT
WORK!!!!!!!!!!!!!!!!!

IF YOU DRIVE THE RESET PIN OF THE 68332 WITH A TOTEM POLE DRIVER (AS OPPOSED
TO AN OPEN COLLECTOR DRIVER) YOUR CIRCUIT WILL BE
MARGINAL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I have seen people use a totem pole driver (even Maximum's parts) and they
use about a 5 Khom resistor (as I recall) between the output of the LVI chip
and the 68332 RESET line.

The whole problem that is being described here is that the LVI chip is NOT
driving the RESET pin of the 68332 high fast enough.  Remember, the RESET
pin of the 68332 is an output when the 68332 is asserting reset.  This makes
the LVI chip FIGHT the 68332.  Not a good thing.  

If you want to send me a copy of the schematic that just shows the reset
circuitry, I'll take a look at it.

Regards,

Charlie

-----Original Message-----
From: Shyam mali [mailto:sscomputers2@...]
Sent: Thursday, June 19, 2003 8:18 AM
To: 68300@yahoogroups.com
Subject: RE: [68300] Connecting to 332

The reset line of the 332 is tied to the MAX707 through a 4k7 series
resistor. The design is proven, this board ain't. I tried second board of
the same batch and it indicated the same problem. then i isolated all the
pins (pulled up the reset and halt pin(which are shorted in my circuit) and
observed the waveform... it was the same.
Shyam

--

--------- Original Message ---------

DATE: Wed, 18 Jun 2003 18:15:41
From: Scott Newell <newell@...>
To: 68300@yahoogroups.com
Cc: 

>At 12:48 PM 6/18/2003 -0700, Melear Charles-rdph40 wrote:
>
>>Scott,
>>I have seen the exact waveform you are describing.  Here is how a
>>Power ON Reset sequence works.
>
>Don't you mean Shyam Mali?--I'm not the original poster, I was replying to
>the original poster.  
>
>I'm betting on the missing reset line pullup too.
> 
>
>newell
>
>
>

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RE: [68300] Connecting to 332

2003-06-19 by Scott Newell

>2.  Most reset chips or supervisors (that I found anyway) do not recommend
>this low of a resistance (820 ohms) for reset lines.  They cannot handle the
>current draw.

I've had good luck with the Microchip MCP130 series and the Dallas/Maxim
DS1811. I have an older design using a MAX691, but that might be marginal
at 5V--reset pin spec is 7mA typ, 20mA max.  All the designs have the 820
ohm reset pullup, of course!


I was severely burnt by a '707 (not Maxim) chip on an HC11 run once...none
of the 100 boards would work, and it turns out that they were actually '807
silicon marked as '707 devices!  The manufacturer didn't want to believe
me, until I faxed the pages from my lab notebook and sent some of the chips
to 'em.  Got a fresh tube of factory tested parts for my trouble.


newell