MAC7200 datasheet(923/976 Pages) FREESCALE

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Initialization/Application Information

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

845

34.8

Initialization/Application Information

34.8.1

Using a Pin in Peripheral Mode

To use a pin in Peripheral Mode, follow these steps:

1. Using Table 34-6, determine the Port number(s) for the desired peripheral pin(s). Note that, in most

cases, all pins associated with a peripheral should be switched to Peripheral Mode for proper

operation of the peripheral.

2. Using Table 34-11, determine the correct CONFIG register(s) for the selected port number(s).

3. Determine whether a pull-up or pull-down is required.

4. Write 0x80, 0x88 or 0x8C to the selected CONFIG register(s). Note that, in Peripheral Mode, the

values of all bits except the MODE and PULL[1:0] bits are unused.

5. If required, enable the peripheral. See the documentation for the peripheral for more information

on how to do this.

Example 34-1. Enable the IIC module

1. For the IIC module, enable both the SDA and SCL pins. Using Table 34-6, determine that these

pins are located on Port B0 and B1, respectively.

2. Using Table 34-11, determine the addresses for Port BO and B1 to be ’Base + 0x0040’ and ’Base

+ 0x0042’, respectively.

3. Write 0x008C to ’Base + 0x0040’ and 0x008C to ’Base + 0x0042’. Alternatively, it is possible to

write 0x0080 to both addresses (no Pull-up functionality). Use the following example code to do

this:

In File registers.h:

#define PIM_BASE_ADDRESS

0xFC0E8000/* Example only ! */

/* Following example assumes short is 16-bits */

volatile unsigned short *CONFIG_B0 = (volatile unsigned short *)

(PIM_BASE_ADDRESS+0x0040);

volatile unsigned short *CONFIG_B1 = (volatile unsigned short *)

(PIM_BASE_ADDRESS+0x0042);

In File main.c:

#include "registers.h"

*CONFIG_B0 = 0x008C;

// Pull-up enabled

*CONFIG_B1 = 0x008C;

// Pull-up enabled

4. If required, enable the IIC module by writing to the appropriate register in the IIC register map.

MAC7200 Datasheet(PDF) 923 Page - Freescale Semiconductor, Inc