Freescale MC9S08LL16自动调温器参考设计

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Freescale MC9S08LL16自动调温器参考设计

作者：时间：2009-08-28 09:32 来源：

Freescale 公司的自动调温器参考设计采用带LCD驱动器的MC9S08LL16超低功耗MCU. 自动调温器调节系统,房间或建筑物的温度,保持在所需的温故而知新范围.为了控制温度,数字自动调温器连接到加热器,通风和空调(HVAC)单元,为HVAC系统提供指示. MC9S08LL16的超低功耗和8位HCS08 CPU很适合用在低功耗的LCD应用.本文介绍了MC9S08LL16主要特性,方框图以及自动调温器参考设计方框图,各部分电路图和完整的电路图与温度传感器的各点温度系数.

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:

Thermostat Reference Design Using the MC9S08LL16 Ultra-Low-Power MCU with LCD Driver
MC9S08LL16 系列主要特性:

• 8-Bit HCS08 Central Processor Unit (CPU)

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

– 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主要应用:

Battery-operated handheld devices

Portable health care devices

Thermostats

Alarms/clocks

Exercise equipment

Personal diagnostics

Calculators

Low-end utility metering

ZigBee® nodes with display

Scrolling text displays

Small appliances

图1.MC9S08LL16系列方框图

自动调温器参考设计

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.

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

图2.自动调温器方框图

图3.高端自动调温器参考设计外形图

high-end thermostat

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.