Version 1 ColdFire Debug (CF1_DEBUG)
MCF51CN128 Reference Manual
,
Rev. 6
20-66
Freescale Semiconductor
The move-to-SR, STLDSR, and RTE instructions include an optional PST = 0x3 value, indicating an entry
into user mode.
Similar to the exception processing mode, the stopped state (PST = 0x1E) and the halted state
(PST = 0x1F) display this status for two entries when the ColdFire processor enters the given mode.
20.4.4
Freescale-Recommended BDM Pinout
Typically, a relatively simple interface pod is used to translate commands from a host computer into
commands for the custom serial interface to the single-wire background debug system. Depending on the
development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port,
or some other type of communications such as a universal serial bus (USB) to communicate between the
host PC and the pod. The pod typically connects to the target system with ground, the BKGD pin, RESET,
and sometimes V
DD
. An open-drain connection to reset allows the host to force a target system reset,
useful to regain control of a lost target system or to control startup of a target system before the on-chip
nonvolatile memory has been programmed. Sometimes V
DD
can be used to allow the pod to use power
from the target system to avoid the need for a separate power supply. However, if the pod is powered
separately, it can be connected to a running target system without forcing a target system reset or otherwise
disturbing the running application program.
Figure 20-26. Recommended BDM Connector
2
4
6
GND
RESET
V
DD
1
3
5
BKGD
No Connect
No Connect