TNETV1002IDZHK datasheet(49/102 Pages) TI1

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MCU Subsystem Functional Overview

June 2001 -- Revised December 2002

SPRS180C

4.3.5 MCU Inter-Integrated Circuit (I2C) Interface

The master I2C interface module provides an interface between the MCU subsystem bus and the I2Cpins,

allowing the MCU to control external peripheral devices connected to the I2C pins. Fundamentally, the I2C

interface module is a parallel-to-serial and serial-to-parallel converter. The parallel data received from the

MCU for transmit has to be converted to a suitable serial form for external peripheral devices on the I2CBus™.

Conversely, the serial data received from the I2C bus has to be converted to a suitable parallel form for passing

to the MCU.

The I2C interface features are:

•

Operates as an I2C master only; cannot be configured as an I2Cslave

•

Supports 7-bit I2C device address

•

Supports an 8-bit I2C device subaddress

•

Master write to slave receiver in single or multiple mode (data loop)

•

Provides a 16-byte transmit FIFO to reduce MCU overhead

•

Supports simple read cycle, read combined cycle

•

A 3-bit programmable prescale internal clock divider and 7-bit programmable SCL clock divider to support

a wide range of input clock frequencies. The I2C SCL clock frequency are:

I2C Standard Mode: 100 kHz

I2C Fast Mode: 400 kHz

•

3-bit programmable spike filter to provide noise filtering on the I2C data input signal

The module does not support:

•

I2C bus 10-bit addressing

•

I2C bus CBUS compatibility

•

Multi-Master I2C

•

Clock synchronization as a handshake: slave devices are NOT allowed to hold the SCL line LOW to force

the master (5471) into a wait state until the slave is ready for the next transfer.

4.3.6 MCU Timers

The 5471 MCU subsystem implements three 16-bit timers configurable either in “auto reload” or in “count

down to zero and stop” modes. Each timer can generate an interrupt to the MCU when it counts down to zero.

The TIMER0 may be configured as either a watchdog counter or as a general-purpose timer. The two others

(TIMER1 and TIMER2) are general-purpose timers.

TIMER2 may be used to provide timing to an external device via the shared pin GPIO19/TIMER_OUT. When

this pin is configured to provide TIMER_OUT, the pin will provide a low pulse when the TIMER2 interrupt

occurs.

4.3.6.1

General-Purpose Timers

TIMER1 and TIMER2, are general-purpose timers, and can be programmed to provide specific timing via a

clock prescale value (PTV) and a starting count value (LOAD_TIM). The timer counts down to zero from the

LOAD_TIM value, changing value every n MCU subsystem clocks, depending on the PTV value. The time

between interrupts to the MCU interrupt handler is defined as:

tint =tclk * (LOAD_TIM + 1)* 2(PTV + 1)

If the counter’s auto-reload (AR) bit is set when the counter reaches zero, the timer will auto-reload the

LOAD_TIM value into its counter and start counting again.

The counter will only run when its start (ST) bit is set. The PTV and AR bits of the CNTL_TIMER register and

LOAD_TIM must not be programmed when the timer is running. The TIMERn current counter value may be

read via the VALUE_TIMn register.

I2C Bus is a trademark of Philips Electronics N. V. Corporation.

TNETV1002IDZHK 数据表(PDF) 49 Page - Texas Instruments

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