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ST9 USER GUIDE

5.5 GLOBAL INITIALISATION: CORE AND PERIPHERALS

5.5.1 Core Initialisation

Set the lower program memory addresses to the addresses of the interrupt service routines

that the peripherals will use.

Initialise the core, as shown above.

Initialise the PLL.

If the Multifunction Timers are to work synchronously, you must start them at the same time.

To do this,

Reset the Global Counter ENable bit (GCEN, bit 7 of register CICR) before the MFTs are ini-

tialised.

Then set it just before the main program starts.

Initialise the memory. This may include:

Resetting the register file and/or the data memory to zero, and

Preloading the variables with the initial values.

The procedure to follow when programming in C is described above.

5.5.2 Peripheral Initialisation

It is now time to configure the peripherals. For each one, you must take the following steps:

Set the Page Pointer Register to the page that contains the peripheral's registers. On some

peripherals, several pages are involved so set the Page Pointer Register accordingly.

Set the various registers that define the behavior of the peripherals. In some cases, you have

to set them in a certain order. Refer to the appropriate Data Sheet. Do not yet set the bits that

start the peripheral working.

Set the Interrupt Vector Register of each peripheral to point to the corresponding group of

pointers to the interrupt service routines in program memory.

You can now set the Interrupt Mask Register, since the global Interrupt ENable bit is reset.

If you are using DMA, set the DAPR and DCPR registers to point to two registers in the reg-

ister file. Then:

– Initialise the address register to the address of the buffer in which the data is to be stored.

– Set the counter register to zero to inhibit DMA transfers.

You can now set the peripheral Enable bit or Start bit, unless you only want it to start later (as

can be the case with the Watchdog Timer).

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