Texas Instruments MSP430x1xx - Manual (Page 34)

System Reset and Initialization
3-4
3.1.2 Device Initialization After System Reset
After a device reset (POR/PUC combination), the initial system conditions are:
- I/O pins switched to input mode (see note below).
- I/O flags are cleared as described in the I/O chapter (see note below).
- Other peripherals and registers initialized as described in their respective
chapters.
- Status register is reset.
- Program counter is loaded with address contained at reset vector location
(0FFFEh). CPU execution begins at that address.
Note:
I/O pins and flags are only initialized after power-up. After the ’430 is
powered and running, if a reset is generated with RST/NMI pin (in reset
mode), the I/O pins are unaffected.
After a system reset, the user program can evaluate the various flags to
determine the source of the reset and take appropriate action.
The initial state of registers and peripherals is discussed in each applicable
section of this manual. Each register is shown with a key indicating the
accessibility of the register and the initial condition, for example,
rw–(0), or
rw–0. In these examples, the r indicates read, the w indicates write, and the
value after the dash indicates the initial condition. If the value is in parenthesis,
the initial condition takes effect only after a POR – a PUC alone will not effect
the bit(s). If the value is not in parenthesis, it takes effect after a PUC alone or
after a POR/PUC combination. Some examples follow:
Type Description
rw–(0) Read/write, reset with POR
rw–0 Read/write, reset with POR or PUC
r–1 Read only, set with POR or PUC
r Read only, no initial state
w Write only, no initial state