Chapter 13

Inter-Integrated Circuit (S08IICV2)

13.1Introduction

The inter-integrated circuit (IIC) provides a method of communication between a number of devices. The interface is designed to operate up to 100 kbps with maximum bus loading and timing. The device is capable of operating at higher baud rates, up to a maximum of bus clock/20, with reduced bus loading. The maximum communication length and the number of devices that can be connected are limited by a maximum bus capacitance of 400 pF.

All MCF51QE128 Series MCUs feature the one or two IICs, as shown in Figure 13-1.

NOTE

The SDA and SCL should not be driven above VDD. These pins are psuedo open-drain containing a protection diode to VDD.

13.1.1Module Configuration

The IIC1 module pins, SDA and SCL, can be repositioned under software control using SOPT2[IIC1PS] as shown in Table 13-1. This bit selects which general-purpose I/O ports are associated with IIC1 operation.

Table 13-1. IIC1 Position Options

SOPT2[IIC1PS]

Port Pin for SDA

Port Pin for SCL

 

 

 

0 (default)

PTA2

PTA3

 

 

 

1

PTB6

PTB7

 

 

 

13.1.2Interrupt Vectors

For MCF51QE128 Series MCUs with two IICs, both IICs share a single interrupt vector. When interrupts are enabled for both IICs, the IICF bit must be polled in the IIC1S and IIC2S registers to determine which IIC caused the interrupt. See Chapter 8, “Interrupt Controller (CF1_INTC),” for the IIC interrupt vector assignment.

MCF51QE128 MCU Series Reference Manual, Rev. 3

Freescale Semiconductor

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Freescale Semiconductor MCF51QE128RM manual Chapter Inter-Integrated Circuit S08IICV2, Module Configuration, SOPT2IIC1PS