Maxim Integrated Secure Microcontroller - Manual (Page 139)

Secure Microcontroller User’s Guide
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16.4 Exiting the Loader
In the DS5000 series, the RST pin must be driven low or allowed to float and the PSEN signal should be
allowed to float. The RST pin has an internal pulldown. The PSEN is an output and drives itself. Note
that both of these conditions must occur or the loader will not be exited. For the DS5001/2, there are
several options. If the RST and
PSEN option is used, they must be removed as described above. If PROG
is pulled low, it can either be returned high or the Exit “E” command can be issued. Since the loader is
edge activated, this will restart the user’s code even while the
PROG pin is low. If power were to cycle
while the PROG pin were low, the loader would be invoked on power-up. The flow of these conditions is
shown in Figure 16-1 .