MICROCHIP 公司的PIC18F2585/2680/4585/4680是 28/40/44引脚的增强型闪存微控制器，具有ECAN™和nanoWatt技术以及10位ADC，适合许多高性能和对功耗敏感的应用。本文介绍了PIC18F 2680和PIC18F 4680在汽车轮胎监测系统（TPMS）的应用。首先介绍了PIC18F 2680和PIC18F 4680的主要性能和方框图，接着介绍了APGRD003 汽车轮胎监测系统（TPMS）的主要电路。

APGRD003 Tire Pressure Measurement SYSTEM

PIC18F2585/2680/4585/4680 28/40/44-Pin Enhanced Flash Microcontrollers with

ECAN TECHNOLOGY, 10-Bit A/D and nanoWatt Technology

Power Managed Modes:

Run: CPU on, peripherals on

Idle: CPU off, peripherals on

Sleep: CPU off, peripherals off

Idle mode currents down to 5.8 A typical

Sleep mode currents down to 0.1 A typical

Timer1 Oscillator: 1.1 A, 32 kHz, 2V

Watchdog Timer: 2.1 A

Two-Speed Oscillator Start-up

Flexible Oscillator Structure:

Four CRYSTAL modes, up to 40 MHz

4x Phase Lock Loop (PLL) – available for crystal and internal oscillators

Two External RC modes, up to 4 MHz

Two External Clock modes, up to 40 MHz

Internal oscillator block:

8 user selectable frequencies, from 31 kHz to 8 MHz

Provides a complete range of clock speeds, from 31 kHz to 32 MHz when used with PLL

User tunable to compensate for frequency drift

Secondary oscillator using Timer1 @ 32 kHz

Fail-Safe Clock MONITOR

Allows for safe shutdown if peripheral clock stops

Special Microcontroller Features:

C compiler optimized architecture with optional extended instruction set

100,000 erase/write cycle Enhanced Flash PROGRAM MEMORY typical

1,000,000 erase/write cycle Data EEPROM memory typical

Flash/Data EEPROM Retention: > 40 years

Self-programmable under SOFTWARE control

Priority levels for interrupts

8 x 8 SINGLE Cycle HARDWARE Multiplier

Extended Watchdog Timer (WDT):

Programmable period from 41 ms to 131s

Single-Supply 5V In-Circuit Serial PROGRAMMING™ (ICSP™) via two pins

In-Circuit Debug (ICD) via two pins

Wide operating VOLTAGE range: 2.0V to 5.5V

Peripheral Highlights:

High current sink/source 25 mA/25 mA

Three external interrupts

One Capture/Compare/PWM (CCP1) MODULE

Enhanced Capture/Compare/PWM (ECCP1) module (40/44-pin DEVICES only):

One, two or four PWM outputs

Selectable polarity

Programmable dead time

Auto-Shutdown and Auto-Restart

MASTER Synchronous Serial Port (MSSP) module supporting 3-wire SPI (all 4 modes) and I2C™ Master and Slave modes

Enhanced Addressable USART module:

Supports RS-485, RS-232 and LIN 1.3

RS-232 operation using internal oscillator block (no external crystal required)

Auto-Wake-up on Start bit

Auto-Baud Detect

10-bit, up to 11-channel Analog-to-Digital CONVERTER module (A/D), up to 100 Ksps

Auto-acquisition capability

Conversion available during Sleep

Dual analog comparators with input multiplexing

ECAN Module Features:

Message bit rates up to 1 Mbps

Conforms to CAN 2.0B ACTIVE Specification

Fully backward compatible with PIC18XXX8 CAN MODULES

Three modes of operation:

Legacy, Enhanced Legacy, FIFO

Three dedicated transmit buffers with prioritization

Two dedicated receive buffers

Six programmable receive/transmit buffers

Three full 29-bit acceptance masks

16 full 29-bit acceptance filters w/ DYNAMIC association

DeviceNet™ data byte filter support

Automatic REMOTE frame HANDLING

ADVANCED error management features