Freescale MC9S08LL16自动调温参考设计

Freescale公司的MC9S08LL16自动调温参考设计具有8位HCS08中央处理器器件(CPU)，片上存储器，省电模式，时钟源选项，系统保护，开发支持，外设，输入/输出，以及封装选项等性能。本文主要介绍了MC9S08LL16特性和方框图、自动调温方框图、低端和高端调温图，配置图等。

Thermostat Reference Design

MC9S08LL16 Series Covers: MC9S08LL16 and MC9S08LL8

Features

• 8-Bit HCS08 Central Processor Unit (CPU)

– Up to 20-MHz CPU at 3.6V to 1.8V across temperature range of -40°C to 85°C

– HC08 instruction set with added BGND instruction

– Support for up to 32 interrupt/reset sources

• On-Chip Memory

– Dual Array FLASH read/program/erase over full operating voltage and temperature

Random-access memory (RAM)

– Security circuitry to prevent unauthorized access to RAM and FLASH contents

• Power-Saving Modes

– Two low power stop modes

– Reduced power wait mode

– Low power run and wait modes allow peripherals to run while voltage regulator is in standby

– Peripheral clock gating register can disable clocks to unused modules, thereby reducing currents.

– Very low power external oscillator that can be used in stop2 or stop3 modes to provide accurate clock source to real time counter

– 6 usec typical wake up time from stop3 mode

• Clock Source Options

– Oscillator (XOSC) — Loop-control Pierce oscillator; Crystal or ceramic resonator range of 31.25 kHz to 38.4 kHz or 1 MHz to 16 MHz

– Internal Clock Source (ICS) — Internal clock source module containing a frequency-locked-loop (FLL) controlled by internal or external reference; precision trimming of internal reference allows 0.2% resolution and 2% deviation over temperature and voltage; supports bus frequencies from 1MHz to 10 MHz.

• System Protection

– Watchdog computer operating properly (COP) reset with option to run from dedicated 1-kHz internal clock source or bus clock

– Low-Voltage Warning with interrupt

– Low-Voltage Detection with reset or interrupt

– Illegal opcode and illegal address detection with reset

– Flash block protection

• Development Support

– Single-wire background debug interface

– Breakpoint capability to allow single breakpoint setting during in-circuit debugging (plus two more breakpoints in on-chip debug module)

– On-chip in-circuit emulator (ICE) debug module containing three comparators and nine trigger modes. Eight deep FIFO for storing change-of-flow addresses and event-only data. Debug module supports both tag and force breakpoints

• Peripherals

– LCD — 4x28 or 8x24 LCD driver with internal charge pump and option to provide an internally regulated LCD reference that can be trimmed for contrast control.

– ADC — 8-channel, 12-bit resolution; 2.5 μs conversion time; automatic compare function; temperature sensor; internal bandgap reference channel; operation in stop3; fully functional from 3.6V to 1.8V

– ACMP — Analog comparator with selectable interrupt on rising, falling, or either edge of comparator output; compare option to fixed internal bandgap reference voltage; outputs can be optionally routed to TPM module; operation in stop3

– SCI — Full duplex non-return to zero (NRZ); LIN master extended break generation; LIN slave extended break detection; wake up on active edge

– SPI— Full-duplex or single-wire bidirectional; Double-buffered transmit and receive; Master or Slave mode; MSB-first or LSB-first shifting

– IIC — IIC with up to 100 kbps with maximum bus loading; Multi-master operation; Programmable slave address; Interrupt driven byte-by-byte data transfer; supports broadcast mode and 10-bit addressing

– TPMx — Two 2-channel (TPM1 and TPM2); Selectable input capture, output compare, or buffered edge- or center-aligned PWM on each channel;

– TOD— (Time Of Day) 8-bit quarter second counter with match register; External clock source for precise time base, time-of-day, calendar or task scheduling functions; Free running on-chip low power oscillator (1 kHz) for cyclic wake-up without external components.

• Input/Output

– 38 GPIOs, 2 output-only pins

– 8 KBI interrupts with selectable polarity

– Hysteresis and configurable pull up device on all input pins; Configurable slew rate and drive strength on all output pins.

• Package Options

64-LQFP, 48-LQFP and 48-QFN

MC9S08LL16 Series Block Diagram

Thermostat Reference Design Using the MC9S08LL16

A thermostat regulates the temperature of a system, room, or building, keeping the temperature at a desired level. There are different ways to get the temperature measurement in an electronic system, for example the use of a thermistor, thermocouples, and in some cases integrated circuits. To control the temperature a digital thermostat is typically connected to an HVAC unit. The thermostat provides voltage to the heater, venting, and air conditioning (HVAC) terminals indicating to the HVAC system, what should be turned on based on the current system temperature.

The thermostat reference design is an example of how a thermostat can be built taking advantage of the MC9S08LL16 features. The main features of this microcontroller that makes it ideal for low-power LCD applications are:

• Low power consumption with LCD configurations that support operation in low power microampere range, as low as 1.5 μA in the thermostat.

• 32 LCD pins, up to 196 segments with eight backplanes and 18 LCD-pins multiplexed with GPIO giving this module a lot of flexibility.

• Any LCD pin can be frontplane or backplane, simplifying the hardware routing and allowing the use of different LCDs with the same board.

• TOD module with quarter to second and second interrupt. It also has a comparator module that allows waking the MCU up to every 64 seconds.

• Low power blinking model enables an LCD blink without waking the controller that saves power consumption.

• 12 bit ADC that can be triggered by the TOD module.

• Wake from stop, based on time or keyboard event.

Thermostat block diagram

Low-end and high-end thermostat
Features and Advantages

The thermostat reference design has the following features:

• Accuracy of 0.1 ℃

• Day-of-the-week, hours, and minutes calendar for the low-end version, and date, hours, and minutes for the high-end version

• Temperature display in ℃ or °F

• Programmable set points for heating and cooling

• Programmable run and hold mode

• Fan on and auto mode

• Standard HVAC connections

• Current sensing switch and screw-terminals to measure power consumption

• HVAC LED indicators

• Contrast control for the high-end version

Main features of the MC9S08LL16 family used in this reference design are:

• 2 x 28 (low-end) and 8 x 24 (high-end) LCD display to show the temperature, date, and time. Any LCD pin can be used either as frontplane or backplane simplifing the layout work.

• An LCD blink mode to display different messages without waking the MCU using a one second blink period.

• 12 bit ADC that gives more accuracy to the temperature measurement using a thermistor.

• TOD capable of waking the MCU from every quarter second up to every 64 seconds.

• Hardware triggered ADC to start the conversion after the TOD module wakes the MCU. • Stop3 mode keeps the TOD and the LCD working using a typical 6 μA current consumption for the high-end and 1.5 μA for the low end.

• A very low power external oscillator used in stop2 or stop3 modes that provide an accurate clock source to the TOD. The external 32.768 KHz crystal does not need resistors or capacitors to work.

Configuration diagram

MC9S08LL16 connections

HVAC connections

Buttons, LED, and power supply

Optional USB to SCI MC9S08JS16

Complete schematic