FAQ34.pdf

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COP Reset

I am using a debug tool which is interfaced through the JTAG/COP port on the PowerPC

device. When I execute a reset command the processor does not reset and I have to power cycle

the board. Why doesn't the reset from the tool work?

The JTAG/COP debug tools interface through a 16pin header on the target system. This header

has a reset signal on it which is tied into the board reset logic. Depending on how that reset signal

is routed on the target system will determine whether the "entire" board or just the processor is

being reset. Frequently, this reset signal is only routed to the processor. As a result, the reset

from the tool results in the system not being reset. In other instances, this signal is routed to the

system POR reset logic and what is happening is the memory controller chip is being reset.

After that happens the memory controller chip needs to be conﬁgured again in order for the pro-

cessor to access memory. As a result a detailed understanding of the target system is required

when routing this signal on the target system.