Synth-DIY Yahoo! Groups Archives

double bus fault

2003-10-21 by Octagon Entwicklung

Dear Sirs,
I have a question about the double bus fault . 
In a dokumentation (M68331/68332TUD/D) 
"An introduction to the MC68331 and Mc68332"
I found the following statements: 

"If the double bus fault has been disabled by 
clearing the HME-Bit in the system protection register, 
the MCU will remain halted indefinitely and must be reset externaly. "

Is it possible to reset the MCU with the enabled watchdog 
if an double bus fault had occured. Or is the watchdog halted, too.
So the watchdog can not reset the MCU.

"After a double bus fault occurs, the MCU drives the HALT line low, 
and can only restarted by a reset."

When I want to watch the HALT signal at the HALT pin, 
is it necessary to set the HME-BIT ? I do not think so, but am not shure.

Best regards

Joachim

RE: [68300] double bus fault

2003-10-21 by Melear Charles-rdph40

Hello everyone,
 
You are correct, the Watchdog, if enabled, will reset the chip regardless of the setting of the HME bit.
 
Also, you will see the HALT line go low when the internal HALT is asserted.  One way, the HALT line is asserted until a system reset occurs.  Otherwise, the HALT line is asserted until the HALT monitor causes a reset.
 
Regards,
 
Charlie

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-----Original Message-----
From: Octagon Entwicklung [mailto:Entwicklung@...]
Sent: Tuesday, October 21, 2003 9:38 AM
To: 68300@yahoogroups.com
Subject: [68300] double bus fault

Dear Sirs,
I have a question about the double bus fault . 
In a dokumentation (M68331/68332TUD/D) 
"An introduction to the MC68331 and Mc68332"
I found the following statements: 

"If the double bus fault has been disabled by 
clearing the HME-Bit in the system protection register, 
the MCU will remain halted indefinitely and must be reset externaly. "

Is it possible to reset the MCU with the enabled watchdog 
if an double bus fault had occured. Or is the watchdog halted, too.
So the watchdog can not reset the MCU.

"After a double bus fault occurs, the MCU drives the HALT line low, 
and can only restarted by a reset."

When I want to watch the HALT signal at the HALT pin, 
is it necessary to set the HME-BIT ? I do not think so, but am not shure.

Best regards

Joachim

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