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MSP430x11x1
MIXED SIGNAL MICROCONTROLLER
SLAS241C – SEPTEMBER 1999 – REVISED JUNE 2000
11
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
boot ROM containing bootstrap loader (continued)
Program execution begins with the bootstrap vector at 0C00h (boot ROM) if a minimum of two positive edges
have been applied to TEST while RST/NMI is low, and TEST is high when RST/NMI goes from low to high. The
TEST signal is normally used internally to switch pins P1.4, P1.5, P1.6, and P1.7 between their application
function and the JTAG function. If the second rising edge at TEST is applied while RST
/NMI is held low, the
internal TEST signal is held low and the pins remain in the application mode:
RST/NMI PIN
TEST
(Internal)
TEST PIN
Bootstrap loader Starts
V
CC
Test mode can be entered again after TEST is taken low and then back high.
The bootstrap loader will not be started (via the vector in address 0C00h), if:
There were less than two positive edges at TEST while RST/NMI is low
TEST is low if RST/NMI goes from low to high
JTAG has control over the MSP430 resources
Supply voltage VCC drops and a POR is executed
WARNING:
The bootstrap loader starts correctly only if the RST
/NMI pin is in reset mode. If it is switched
to the NMI function, unpredictable program execution may result. However, a
bootstrap-load may be started using software and the bootstrap vector, for example the
instruction BR &0C00h.