Texas Instruments manual MSP50C614/MSP50P614 Initialization Codes

MSP50C614/MSP50P614 Initialization Codes

In any C614 application, it is important for certain components to be located as close as possible to the C614 die or package. These include any of the decoupling capacitors at VDD (0.1 ∝F). It also includes all of the components in the crystal-reference network between OSCIN and OSCOUT (22 pF, 10 MΩ,

32kHz).

6.2MSP50C614/MSP50P614 Initialization Codes

Before any kind of application code can be written, the MSP50C614/ MSP50P614 processor state must be initialized. The initialization code is in- it.asm, where file extension .asm is for an assembly language file.

The entry point to the initialization routine is INIT_DEVICE_614. This entry point must not be called (call INIT_DEVICE_614). A jump to this routine should be used (jmp INIT_DEVICE_614). After the end of initialization, the routine always jumps to the _main, which is the beginning of MSP50P614/ MSP50C614 user code. It is recommended that INIT_DEVICE_614, is per- formed immediately after RESET to ensure that device initialization is always performed at RESET. Users modifying the initialization routine is not recom- mended.

The initialization routine does the following:

-Disables all interrupts.

-Zeros out all accumulators.

-Zeros out all memory.

-Starts oscillators at frequency 8.192 MHz. If CRO_FLAG is 1, then crystal oscillator is started. If CRO_FLAG is 0, then the resistor trim oscillator is started. If resistor trim oscillator is chosen in P614 part, then RESISTOR- TRIM must be defined by the user (this value is written under the P614 part). If the C614 part is used, then the resistor trim is read from I/O location RTRIM (0x2F).

-Delays execution of the core for 200 ms for PLL to stabilize.

-Zeros out system registers.

-Finally jumps to the label _main.

WARNING

If P614 parts are used for development, then the user MUST CHANGE the resistor trim initialization to read from port 0⋅2F when switching to the C6xx part.

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