DRM159, Automotive HVAC Control System with LCD Interface for S12HY Family D ...

Automotive HVAC Control System with
LCD Interface for S12HY Family Devices
Document Number: DRM159
Rev. 0
03/2015
Automotive HVAC Control System with LCD Interface
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Freescale Semiconductor, Inc.
CHAPTER 1
INTRODUCTION
1.1.
1.2.
APPLICATION FEATURES AND COMPONENTS ....................................................................................................................... 5
MC9S12HY64 CONTROLLER ADVANTAGES AND FEATURES .................................................................................................. 6
CHAPTER 2
HARDWARE DESCRIPTION
2.1.
INTRODUCTION ............................................................................................................................................................. 8
2.2.
HARDWARE INTERFACE ................................................................................................................................................... 9
2.2.1. Power supply........................................................................................................................................................ 9
2.2.2. MC9S12HY64 MCU............................................................................................................................................. 10
2.2.3. Liquid Crystal Display (LCD) ................................................................................................................................ 16
2.2.4. Actuator motor driver ........................................................................................................................................ 17
2.2.5. Blower motor driver........................................................................................................................................... 17
2.2.6. MC9S08PT60 for touch sense ............................................................................................................................ 19
2.2.7. IR receiver .......................................................................................................................................................... 20
2.2.8. Temperature sensor........................................................................................................................................... 20
2.2.9. Controller Area Network (CAN) ......................................................................................................................... 21
2.2.10.
Background debug mode (BDM) ................................................................................................................... 21
CHAPTER 3
SOFTWARE DESIGN
3.1.
INTRODUCTION ........................................................................................................................................................... 23
3.2.
SOFTWARE ARCHITECTURE ............................................................................................................................................ 23
3.2.1. LCD graphics display........................................................................................................................................... 25
3.2.2. User interface .................................................................................................................................................... 27
3.2.3. Motor control..................................................................................................................................................... 30
3.2.4. Temperature sensor........................................................................................................................................... 32
3.2.5. Real time clock ................................................................................................................................................... 32
CHAPTER 4
TESTING AND MEASUREMENTS
4.1.
HARDWARE SETUP ....................................................................................................................................................... 33
4.2.
DEBUGGING AND MEASUREMENT ................................................................................................................................... 34
4.2.1. LCD ..................................................................................................................................................................... 34
4.2.2. User interface .................................................................................................................................................... 35
4.2.3. Motor control..................................................................................................................................................... 37
4.3.
TEMPERATURE SENSOR ................................................................................................................................................. 45
APPENDIX A
A.1
SCHEMATIC ................................................................................................................................................................ 46
A.2
LAYOUT ..................................................................................................................................................................... 51
A.2.1
Silkscreen Top .................................................................................................................................................... 51
A.2.2
Silkscreen Bottom .............................................................................................................................................. 51
A.2.3
Top ..................................................................................................................................................................... 52
A.2.4
Bottom ............................................................................................................................................................... 52
APPENDIX B
BILL OF MATERIAL
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
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Chapter 1
Introduction
This document describes the reference design of an automotive Heating, Ventilation, and Air
Conditioning (HVAC) control system with LCD interface board based on MC9S12HY64.
The purpose of the design is to replace the existing mechanical switches, which are prone to wear and
tear, with interactive LCD based system for longevity and robustness of the system. Freescale has a full
portfolio of HVAC design for the entire four-wheeler segments. The design described in this document
is intended for lower and mid segment four-wheelers.
Figure 1.
Conventional HVAC
The reference design replaces mechanical switches used for vent positions, blower speed, and
temperature control. This HVAC control system offers a capacitive touch pad interface (controlled
through proximity capacitive touch sensor), an IR remote control (provided for the ease of rear-seat
passengers) and micro-switches. It drives the actuator and blower motor with the help of a robust Hbridge and intelligent high-current switch. The design provides safety features such as motor stall
detection, motor jams/shorting, open load, etc.
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Introduction
The design also features car cabin’s temperature (in degree Celsius) display, date and time displays, thus
eliminating the need of separate date/time/temperature displays. Date/Time can be easily set through
touch pads/remote control.
Block diagram of MC9S12HY based HVAC system is shown in Figure 2.
Figure 2.
Block diagram
1.1. Application features and components
The salient features of the reference design are as follows:
•
•
LCD based Graphics Interface
Control for airflow (Face, Foot, Defrost, Face & Defrost and Face & Foot) directions using
actuator motors
• Control for defogger using actuator motor
• Control for recirculation using actuator motor
• 5-level control for blower speed using PMDC motor
• 9-level control for cooling/warming using actuator motor
• Car cabin’s temperature display
• Real Time Clock display and adjustment
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Introduction
• Date display and adjustment
• IR remote interface
• 8 Touch pad interface using PT60 MCU
• Low Power Mode interfaced through Ignition
The package that shall be supplied to the user for developing the HVAC system based on MC9S12HY64
MCU includes:
• Hardware – Reference HVAC board
• Documentation – DRM, BOM, Schematics
1.2. Advantages and features of MC9S12HY64 controller
Advantage of using MC9S12HY64:
• In-built LCD driver capable of driving 160 segments
• Stepper Motor Controller
• Low-voltage detect (LVD) with low-voltage interrupt (LVI) and Low-voltage reset (LVR)
• MCU security mechanism that prevents unauthorized access to the Flash memory
• Two static low-power modes Pseudo Stop and Stop mode to facilitate power saving when full
system performance is not required
The general features of MC9S12HY64 MCU are:
• HCS12 CPU core, 32 MHz bus frequency (64 MHZ core frequency)
• Up to 64 KB on-chip flash with ECC
• 4 KB data flash with ECC
• Up to 4 KB on-chip SRAM
• LCD driver, configurable up to 40 x 4, all LCD pins are multiplexed with GPIOs
• Stepper motor controller with up to four drivers
• Phase locked loop (PLL) frequency multiplier with internal filter
• 4–16 MHz amplitude controlled Pierce oscillator
• 1 MHz internal RC oscillator
• Two timer modules (TIM0 and TIM1) supporting input/output channels that provide a range of
16-bit input capture, output compare, counter, and pulse accumulator functions
• Pulse width modulation (PWM) module with up to eight 8-bit channels
• Autonomous periodic interrupt (API)
• Up to 8-channel, 10-bit resolution successive approximation analog-to-digital converter (ATD)
• One serial peripheral interface (SPI) module
• One serial communication interface (SCI) module supporting LIN 2.0, 2.1, and SAE J2602
communications
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Introduction
•
•
•
•
•
On-chip voltage regulator (VREG) for regulation of input supply and all internal voltages
One Inter-Integrated Circuit (I2C) module
One multi-scalable controller area network (MSCAN) module (supporting CAN protocol
2.0A/B)
Up to 22 key wakeup inputs
Available in 64 LQFP and 100 LQFP packages
Figure 3.
Block diagram of S12HY family
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Hardware Description
Chapter 2
Hardware Description
2.1. Introduction
The reference design consists of:
•
•
•
•
•
•
•
•
•
•
Power supply section
100-pin LQFP packaged MC9S12HY64 MCU
132 segment (33X4) LCD Glass interface with backlight control
Dual Intelligent High-current Self-protected Silicon High Side Switch, MC33984, capable of
driving two blower motors of 15 A each
Two Throttle Control H-Bridge, MC33932, for controlling four high current actuator motors,
three of these are used for temperature, vent position, and re-circulation, while one of the motor
control has been kept for future use
64-pin MC9S08PT60 which has Touch Sense Input (TSI) module for eight touch pad interface
IR remote interface, provided especially for the ease of control for rear-seat passengers
Temperature sensor, for measuring the car’s cabin temperature
CAN interface for communication with various other units
Ignition control section for low-power mode simulation
Figure 4.
S12HY based HVAC reference design PCB – MCU side
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Hardware Description
Figure 5.
S12HY based HVAC reference design PCB – LCD side
2.2. Hardware interface
The following section details each hardware block with the corresponding schematic.
2.2.1. Power supply
The reference design board is switched on from an automotive battery, 12 V, 32 AH. It is connected
directly with
• Blower motor driver, MC33984, as the blower motor is 12 V compatible
• Actuator motor driver, MC33932, as the actuator motors are 12 V compatible
Signal conditioning circuitry has been added on 12 V supply to avoid any negative spikes.
Figure 6.
Signal conditioning circuitry on input supply
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Hardware Description
A switching regulator LM2676S-5.0 is used to generate a 5 V power supply to the MCU and the
connected peripherals, which include:
• Temperature sensor
• IR receiver
• Digital interface of MC33984
• Digital interface of MC33932
• Controller Area Network transceiver
• LCD Glass backlight
Figure 7.
Switching regulator section
The design has a power grid controlled by the S12HY MCU to control power consumption during lowpower mode.
Figure 8.
MCU controlled peripheral power grid
2.2.2. MC9S12HY64 MCU
MC9S12HY64 is an automotive, 16-bit microcontroller including error correction code (ECC) on flash
memory, a separate data-flash module for diagnostic or data storage, a fast analog-to-digital converter
(ADC) and a frequency modulated phase locked loop (IPLL) that improves the EMC performance. This
family also services generic automotive applications requiring CAN, LCD, Motor driver control, or
LIN/J2602. Typical examples of these applications include automotive HVAC system, entry level
instrument clusters, automotive audio system, general purpose motor control, and body controllers.
The MC9S12HY family delivers all the advantages and efficiencies of a 16-bit MCU while retaining the
low cost, power consumption, EMC, and code-size efficiency advantages.
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Freescale Semiconductor, Inc.
Hardware Description
The reference design utilizes the following modules of MC9S12HY64:
1. LCD controller to drive 33X4 LCD.
2. Motor Controller module to drive Actuator motors.
3. SPI and TIM module for controlling and driving the blower motor driver IC and PT60 for Touch
sense application.
4. TIM module for interfacing IR remote control.
5. BKGD for programming.
6. CAN interface for communication.
7. ADC module for Temperature sensor and stall detection of blower and actuator motors.
8. IRQ/XIRQ as a wakeup source.
9. RTI module for time keeping.
The design uses 8 MHz crystal for feeding the PLL and also acts as the source for time keeping.
Figure 9.
Crystal section
The functional pin assignment for MC9S12HY64 is described in Table 1 and the schematic in Figure 10:
Table 1.
Pin#
Pin
Assignment
Functional pin assignment
Purpose
Major Block
1
—
—
2
—
—
3
M0C0M
Actuators (U10_IN1) (Fresh Air)
Actuators
4
M0C0P
Actuators (U10_IN2) (Fresh Air)
Actuators
5
M0C1M
Actuators (U11_IN3) (Temp)
Actuators
6
M0C1P
Actuators (U11_IN4) (Temp)
Actuators
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Hardware Description
7
Supply
Supply
8
Supply
Supply
9
M1C0M
Actuators (U11_IN1) (Mode)
Actuators
10
M1C0P
Actuators (U11_IN2) (Mode)
Actuators
11
M1C1M
Actuators (U10_IN3)
Actuators
12
M1C1P
Actuators (U10_IN1)
Actuators
13
MISO
SPI (used for Blower motor/PT60)
SPI
14
MOSI
SPI (used for Blower motor/PT60)
SPI
15
SCK
SPI (used for Blower motor/PT60)
SPI
16
SS
SPI (used for Blower motor)
SPI
17
Supply
Supply
18
Supply
Supply
19
IOC1_2
Used for Edge detect for checking
the Stall on
Blower Motor
20
PV5
Chip Select for PT60
Touch Sensor
21
PV6
IR data pin
IR
22
PV7
Peripheral power control
Power
23
—
—
—
24
—
—
—
25
RXD
UART (RXD)
UART
26
TXD
UART (TXD)
UART
27
RXCAN
CAN (RX)
CAN
28
TXCAN
CAN (TX)
CAN
29
—
—
—
30
PWM1
IN1 (MC33984)
Blower Motor
31
PWM2
IN2 (MC33984)
Blower Motor
32
—
—
—
33
PT60_IRQ
IRQ for Touch Sensor
Touch sensor
34
BLR_WK
Blower Motor wake up
Blower Motor
35
BLR_FAULT
Blower Motor Fault
Blower Motor
36
BLR_RST
Blower Motor Reset
Blower Motor
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Hardware Description
37
FP0
LCD (pin 11)
LCD
38
FP1
LCD (pin 10)
LCD
39
FP2
LCD (pin 9)
LCD
40
FP3
LCD (pin 8)
LCD
41
FP4
LCD (pin 7)
LCD
42
FP5
LCD (pin 6)
LCD
43
FP6
LCD (pin 5)
LCD
44
FP7
LCD (pin 4)
LCD
45
—
—
—
46
—
—
—
47
FP10
LCD (pin 3)
LCD
48
FP11
LCD (pin 2)
LCD
49
FP12
LCD (pin 1)
LCD
BDM Interface
BDM Interface
50
51
—
—
—
52
—
—
—
53
FP15
LCD (pin 12)
LCD
54
FP16
LCD (pin 13)
LCD
55
FP17
LCD (pin 14)
LCD
56
FP18
LCD (pin 15)
LCD
57
FP19
LCD (pin 16)
LCD
58
FP20
LCD (pin 17)
LCD
59
FP21
LCD (pin 18)
LCD
60
FP22
LCD (pin 19)
LCD
61
Supply
Supply
62
Supply
Supply
63
PH4
Actuator Motor Control
Actuator
64
FP24
LCD (pin 41)
LCD
65
FP25
LCD (pin 36)
LCD
66
FP26
LCD (pin 35)
LCD
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Hardware Description
67
FP27
LCD (pin 34)
LCD
68
FP28
LCD (pin 33)
LCD
69
Supply
Supply
70
Supply
Supply
71
Supply
Supply
72
Crystal
Crystal
73
Crystal
Crystal
74
IRQ
Ignition
Ignition
75
PA1
Actuator Motor Control
Actuator
76
FP31
LCD (pin 32)
LCD
77
FP32
LCD (pin 31)
LCD
78
FP33
LCD (pin 30)
LCD
79
FP34
LCD (pin 29)
LCD
80
FP35
LCD (pin 28)
LCD
81
FP36
LCD (pin 27)
LCD
82
FP37
LCD (pin 26)
LCD
83
FP38
LCD (pin 25)
LCD
84
FP39
LCD (pin 24)
LCD
85
BP0
LCD (COM1)
LCD
86
BP1
LCD (COM2)
LCD
87
BP2
LCD (COM3)
LCD
88
BP3
LCD (COM4)
LCD
89
VLCD supply
LCD Controller Supply
LCD Controller Supply
90
BDM Interface
BDM Interface
91
Supply
Supply
92
Supply
Supply
93
AN00
Temp Sensor I/p Data
Temp Sensor
94
AN01
Feedback for Temp Actuator
Feedbacks
95
AN02
Feedback for Mode Actuator
Feedbacks
96
AN03
Feedback for Blower Motor
Feedbacks
97
AN04
M0C0M(DNP) (Fresh Air Actuator)
Feedbacks
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Freescale Semiconductor, Inc.
Hardware Description
98
AN05
M0C0P(DNP) (Fresh Air Actuator)
Feedbacks
99
BLR_CSNS
Blower Motor Sense
Blower Motor
100
—
—
—
Figure 10. MCU section
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Hardware Description
2.2.3. Liquid Crystal Display (LCD)
132 segments (33X4) LCD Glass, GDC8799D, is interfaced with the MCU. The glass has four back
planes and 33 front planes and is shown in Figure 11.
Figure 11. LCD Glass
The details of the LCD glass are as follows:
1. Viewing angle
:
6 O’clock
2. LCD Type
:
TN, Positive, Transreflective
3. Multiplex level
:
¼ Duty, 1/3 Bias
4. LCD driving voltage :
5.0 V
As the LCD glass is transreflective, backlight has been added to improve its contrast, which is controlled
through the MCU and is shown in Figure 12.
Figure 12. LCD Glass backlight
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Hardware Description
2.2.4. Actuator motor driver
MC33932 is an H-Bridge Power IC that has two independent monolithic H-Bridge Power ICs in the
same package, which is used to drive the actuator motors. The present design uses two such ICs, capable
of driving four motors. Three of these motor drivers have been utilized while one has been kept for
future enhancements. Three actuator motors control include:
• Cooling control
• Air flow vent position control
• Recirculation control
Each actuator motor requires 200 mA @ 12 V of current, which is sourced through MC33932. SMC
module of MCU is used to interface the H-Bridge. The schematic of one of the actuator motor interface
is shown in Figure 13:
Figure 13. Actuator motor section
Two of the actuator motors (temperature and vent position) used in the design have feedback pins,
which return the actuator motor position in the form of 0-5 V signal. It is interfaced with the ADC pin of
the MCU for stall detection.
Recirculation actuator motor is a two wire actuator motor without any feedback, so the stall detection
has been implemented by a different mechanism. The total numbers of cycles, at fixed PWM duty cycle,
required to move the motor from one position to the other (internal to external or vice-versa) is known
(using the calibration process), after which the driving of the motor pin is stopped to implement the stall.
2.2.5. Blower motor driver
Intelligent, high-current, self-protected, silicon, high side switch MC33984 is used to drive high current
blower motor. It is capable of driving two blower motors of 15 A each. It provides many protections,
few of which includes:
•
Over-voltage fault
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Hardware Description
• Over-temperature fault
• Under-voltage shutdown
• Open load fault
• Over-current fault
• Enhanced 16 V reverse polarity VPWR protection
MC33984 is programmed and controlled via the Serial Peripheral Interface (SPI). It communicates
various fault condition to the MCU via its fault status pin (𝐹𝑆) and the same can be read over SPI bus.
The current driver is interfaced with the PWM channel of the MCU for controlling the blower motor
speed. The output of the blower motor is interfaced to the ADC channel to implement stall so that motor
drive could be stopped once the motor jams. The schematic of the blower motor section is shown in
Figure 14.
Figure 14. Blower motor section
The reference design has the support for interfacing two blower motors, as there are HVAC units which
requires two blower motors to be driven. The blower motor used in the design is of the following
specifications:
Table 2.
Blower motor specifications
S. No.
Parameters
Specifications
1
Motor Type
PMDC
2
Motor Rating
Continuous
3
Rated Voltage
12 V
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Hardware Description
4
No Load Current
1.7 A
5
No Load Speed
4500 rpm
6
Rate Torque
0.3 Nm
7
Rated Current
14.5 A
8
Rated Speed
3600 ± 5%
9
Direction of Rotation
CCW
2.2.6. MC9S08PT60 for touch sense
The 8-bit MCU S08PT60 has Touch Sense Interface (TSI) module which is utilized in the design for
capacitive touch sensing. The touch sensing input (TSI) module provides capacitive touch sensing
detection with high sensitivity and enhanced robustness. Each TSI pin implements the capacitive
measurement by a current source scan, charging and discharging the electrode, once or several times. A
reference oscillator ticks the scan time and stores the result in a 16-bit register when the scan completes.
Meanwhile, an interrupt request is submitted to CPU (which is S12ZVH128 in this design) for postprocessing. After receiving the interrupt, S12ZVH128 communicates with PT60 on SPI bus and gets the
information about which pad is touched. The schematic of the capacitive touch sensor is shown in
Figure 15.
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Hardware Description
Figure 15. Capacitive touch sensor section
2.2.7. IR receiver
NEC based IR remote is used to provide the controllability to the user, especially the rear-seat
passengers. IR sensor is interfaced to TIM module channel. The schematic of IR receiver is shown in
Figure 16.
Figure 16. IR receiver section
2.2.8. Temperature sensor
Temperature sensor interfaced to the ADC channel of the MCU provides car cabin’s real time
temperature, which in turn is displayed on the LCD. The sensor provides the voltage that is proportional
to the temperature. The schematic is shown in Figure 17.
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Hardware Description
Figure 17. Temperature sensor section
2.2.9. Controller Area Network (CAN)
This design provides the CAN interface for communication with other system units and the schematic is
shown in Figure 18.
Figure 18. CAN section
2.2.10. Background debug mode (BDM)
The BDM communication interface is used for programming and debugging the MCU. P&E’s USB
multilink is a debug interface which allows a PC to access the BDM on MCU is shown in Figure 19. It
connects between a USB port on a PC and the standard 6-pin berg debug connector on the target
(MCU). The user can directly control the target’s execution, read/write registers and memory values,
debug code on the controller and program internal or external FLASH memory devices. The schematic
of BDM section is shown in Figure 20
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Figure 19. PE micro USB multilink
Figure 20. Background debug section
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Software Design
Chapter 3
Software Design
3.1. Introduction
This chapter describes the embedded software design of the HVAC application based on MC9S12HY64.
This application’s main purpose is to demonstrate MC9S12HY64’s capability to interface LCD, drive
the motors, provide user interface, while maintaining the calendaring information at the same time.
All embedded software of this project was written using CodeWarrior Development Studio for Freescale
S12(X) Microcontrollers, V5.1 which is Windows supported and can be downloaded from
freescale.com.
Software design mainly consists of graphics display, user interface, motor control, real-time temperature
sensing & display, and RTI for time keeping. The controller uses external crystal (8 MHz) and internal
PLL to generate the core/bus clock of 40 MHz/20 MHz.
The software has following main modules:
• LCD graphics display
• User interface
— Capacitive touch pads
— IR remote control
• Motor control with stall detection
— Blower Motor(s)
— Actuator Motors
• Real time temperature sensing
• Real time clock
3.2. Software architecture
MC9S12HY64 is based on a high-speed S12 CPU, 16-bit processing unit that has a programming model
identical to that of the industry standard M68HC11 CPU. All the tasks are scheduled on round robin
basis.
Overall system flowchart is shown in Figure 21 and the system memory map in Table 3.
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Software Design
Figure 21. System flowchart
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Software Design
Table 3. Memory map
Module Name
Code Memory
Data Memory
ADC
65
1
Actuator Motors
1,812
122
Blower Motor
538
13
Clock
30
0
IR Remote
727
17
LCD
8,245
27
Push Buttons
129
0
RTC
351
11
Temperature Sensor
80
6
Touch
250
1
Data Page
185
0
Main
2,513
27
Total
14,925
225
The following subsection describes each of the modules and its design flow.
3.2.1. LCD graphics display
Figure 22. LCD major blocks
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Software Design
The existing HVAC units use mechanical knobs, which in the present design have been shown on LCD.
Major blocks of LCD are shown in Figure 22, which include
•
•
Date display – shows the date in DD/MM/YY format.
Time display – shows the Time in HH:MM format. User can select between 24H/12H display
format.
• Cabin temperature display – displays the car’s real time cabin temperature.
• Fan position – A fan is made up of four spokes/blades, as is shown in Figure 23. L1 shows the
position 1 of all the four spokes of the fan, L2 shows position 2, and L3 shows position 3.
Rotation of the fan is a function of blower motor speed, higher the blower motor speed faster the
fan will rotate.
Figure 23. Fan positions
• Blower speed – shows the speed of the blower motor at which it is currently running.
• AC display – shows AC on/off position.
• Defogger – it is shown when the defogger is switched on.
• Cooling control display – it is a 9-level display for showing the level of cooling/heating. Any
level indicates the mixing of hot/cold air through the vents using the flap control. The flap will
be positioned to one extreme, for level 1 display, allowing only the cold air to flow, while it will
be positioned on the other extreme, level 9 allowing only the hot air to flow.
• Air flow position – shows the vent position for the air flow. There are total of five possible
positions as per the HVAC units used
— Face
— Foot
— Face & Foot
— Defrost
— Foot & defrost
In each of the above case the corresponding text will be displayed
• Recirculation display – shows the air circulation is fresh-air/recirculation-air.
All the above displays, except temperature display can be controlled by user interface. The temperature
display shows the cabin’s temperature which is not modifiable by any user interface.
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Software Design
3.2.2. User interface
The reference design has two types of interfaces:
1. IR remote control
2. Capacitive touch pads
These will be discussed in detail in the following section.
3.2.2.1. IR remote control
Figure 24. IR remote control along with key descriptions
NEC protocol based IR remote control is used for the reference design. Each key press updates its
corresponding section on the LCD and is shown in Figure 24. Unmarked keys are kept for future
enhancements. The functionality of each key block is as below:
• AC ON/OFF – AC can be switched ON/OFF with this key, and the corresponding AC status will
be display on LCD.
• Air flow positions – AF +/- keys are used to change the vent positions. Each key press will drive
the vent position actuator motor and the corresponding text and position on the LCD will be
displayed.
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
27
Software Design
Figure 25. AF+/- key press control flow
•
Defogger – defogger can be switched ON/OFF with this key. If the defogger is switched on the
icon will be displayed on LCD
• Recirculation – CIRC is used to select between fresh-air and recirculation-air, which will drive
the fresh air actuator motor and the corresponding arrow on the recirculation section of the LCD
will be displayed.
• Cooling Control – COLD/HOT key are used to change the degree of coldness/hotness in the
vehicle. Pressing this key will drive the cooling actuator motor in the background, while the
COLD/HOT level will be updated on the LCD.
• Blower Speed Control – F+/- keys are used to update the blower speed by increasing the duty
cycle of the PWM used to drive the PMDC blower motor. This will also update the blower speed
on the LCD.
• Date/Time display – Time Menu is used to select between the Date and Time display on the
LCD. When date display is selected, then the Mode key is used to select between
date/month/year, while in time display, it is used to select between hours/minutes/time-format
(AM/PM/24H). Set key increments the selected digit, and once the limit is reached, digit is reset
to zero.
Automotive HVAC Control System with LCD Interface
28
Freescale Semiconductor, Inc.
Software Design
3.2.2.2. Capacitive touch pads
Figure 26. Touch pads
Proximity Capacitive Touch Sensor Controller PT60 is interfaced to the MCU via SPI bus, through
which it communicates the various touch pad pressed. Each touch pad updates its corresponding section
on the LCD and is shown in Figure 26. ON/OFF, DEFG, CIRC, AF+/- have the same functionality as
the corresponding IR remote key, which have already been explained in the above section.
As the number of keys are limited, an innovative way of menu selection has been implemented using the
three keys:
• MENU SELECT
• MODE / +
• SET / ―
When the AC is switched on, the MENU SELECT key, selects between four menu states as shown
below in Figure 27, starting from Blower Motor Menu.
Table 4 shows the functionality of touch pads MODE/+ and SET/ in each mode, which will emulate the
functionality of IR remote keys.
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
29
Software Design
Figure 27. Menu Select control flow
Functionality of Mode/Set keys when Menu key is active
Table 4.
1.
S. No.
Menu Mode
Mode Key Function1
Set Key Function1
1
Blower Speed
F+
F―
2
Cooling Control
HOT
COLD
3
Date
MODE
SET
4
Time
MODE
SET
The touch key function emulates the IR keys are listed here
3.2.3. Motor control
The reference design has two types of motor control
• Blower motor control
• Actuator(s) motor control
These will be discussed in detail in the following section
3.2.3.1. Blower motor control
Blower Motor control is implemented using PWM channel of the MCU and is driven through the highcurrent switch MC33984. PWM duty cycle is varied as per the blower speed set through the user
interface. The duty cycle and the blower speed are shown in Table 5.
Automotive HVAC Control System with LCD Interface
30
Freescale Semiconductor, Inc.
Software Design
Blower Speed and Duty cycle
Table 5.
Blower Speed Levels
Duty Cycle (%)
0
0
1
10
2
20
3
40
4
60
NOTE
PWM’s frequency is 20 Hz (approx)
Blower motor may develop fault due to mechanical or electrical reason because of which it may be
jammed. Driving high current blower motor under such condition may lead to permanent damage of its
coils. To avoid this, stall detection is implemented in the design, for which the output of the MC33984 is
continuously monitored on the ADC channel of the MCU for generated back E.M.F.
3.2.3.2. Actuator motor(s) control
Actuator motor(s) control is implemented using Motor Controller module of the MCU and is driven
through the high-current H-Bridge MC33932. Actuator motor control consists of:
• Cooling control actuator motor – controls the mixing of hot and cold air. It controls the flap
position of the mixer unit as per the degree of coldness/hotness set through the user interface.
• Air flow vent position control – controls the air direction flow. It controls the flap position of the
actuator motor, having five possible positions, settable through user-interface. These are:
— Face
— Foot
— Face & Foot
— Defrost
— Defrost & Foot
• Recirculation control – controls the fresh air circulation in the vehicle. It controls the
recirculation actuator motor, which open/closes the flap for inlet of the fresh air. This is
controlled using the CIRC key/pad on IR remote/Touch pads.
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
31
Software Design
3.2.4. Temperature sensor
A temperature sensor has been interfaced with the MCU on the ADC channel, which is used to monitor
the vehicle’s cabin temperature. The temperature is read continuously and the average temperature is
shown on the LCD.
3.2.5. Real time clock
The application integrates the Real time clock and calendaring information and displays it on the LCD;
RTI is used for this purpose, which generates the interrupt periodically. In the reference design the
periodicity of the interrupt is 250 ms.
The application supports the setting of date and time through user interface. User can also select the time
format as 24H/12H.
Automotive HVAC Control System with LCD Interface
32
Freescale Semiconductor, Inc.
Testing and Measurements
Chapter 4
Testing and Measurements
4.1. Hardware setup
The jumper and test point placement on the board are shown in Figure 28 and their settings in Table 6,
which are useful for board bring up.
Figure 28. Jumper settings
Table 6.
Jumper settings
Jumper
Functionality
J1
Power connections on the board
J2
VLCD
1-2
J3
SCI connector
―
J4
S12 BDM Connector
―
HVAC unit 18 pin connector
―
J5
Connection
1: +12V
2: GND
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
33
Testing and Measurements
MC33984 Sense back
―
J8
HS0 Blower motor feedback
connected to ADC channel
J9
CAN termination connector
―
J10
CAN connector
―
J11
PT60 Reset Connector
―
J12
GPIO Connector
―
J13
PT60 BDM connector
―
J14
PT60 Power Selection Pin
2-3
4.2. Debugging and measurement
In this section, waveforms are shown for each section.
4.2.1. LCD
For testing the LCD, probe any of the frontplane pin, on which there is one ON segment. The waveform
on such a pin will be as shown below:
Automotive HVAC Control System with LCD Interface
34
Freescale Semiconductor, Inc.
Testing and Measurements
Figure 29. Waveform - a front plane with exactly one ON segment
4.2.2. User interface
For testing the IR receiver section, IR receiver data pin should be probed. The following waveform will
be observed when a single key is pressed for a long time.
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
35
Testing and Measurements
Figure 30. Waveform – when a single key is pressed for a long time
Automotive HVAC Control System with LCD Interface
36
Freescale Semiconductor, Inc.
Testing and Measurements
Figure 31. Waveform – when multiple IR keys are pressed at a very fast pace
4.2.3. Motor control
Waveforms for each of the interfaces are shown in following sections.
4.2.3.1. Blower motor
Waveform for blower motor control at different levels (changed using the user interface) is probed at the
MC33984 HS0 pin and is shown in figure below:
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
37
Testing and Measurements
Figure 32. Waveform – Blower motor control at different speed levels
4.2.3.2. Actuators Motor
Waveforms for recirculation actuator motor control in different position, with and without the actuator
motor being interfaced to MC33932, are shown in Figure 33 to Figure 36. The major difference in the
two waveforms when the actuator motor is connected/not connected is the flyback voltage (below the
Gnd level) marked in Figure 33 and Figure 34.
Automotive HVAC Control System with LCD Interface
38
Freescale Semiconductor, Inc.
Testing and Measurements
Figure 33. Recirculation motor control waveform for fresh air to internal circulation, when motor is
connected
Figure 34. Recirculation motor control waveform for internal to fresh air circulation, when motor is
connected
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
39
Testing and Measurements
Figure 35. Recirculation motor control waveform for fresh air to internal circulation, when motor is not
connected
Figure 36. Recirculation motor control waveform for internal to fresh air circulation, when motor is not
connected
Automotive HVAC Control System with LCD Interface
40
Freescale Semiconductor, Inc.
Testing and Measurements
Waveforms for air flow vent position actuator motor control in different positions are shown in Figure
37 to Figure 42. For each position change we have captured the initial phase, transition phase and the
final phase of the waveforms.
Figure 37. Air flow actuator motor control waveform for defrost position to face & foot position - initial
phase
Figure 38. Air flow actuator motor control waveform for defrost position to face & foot position – transition
phase
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
41
Testing and Measurements
Figure 39. Air flow actuator motor control waveform for defrost position to face & foot position – final
phase
Figure 40. Air flow actuator motor control waveform for face position to foot position – initial phase
Automotive HVAC Control System with LCD Interface
42
Freescale Semiconductor, Inc.
Testing and Measurements
Figure 41. Air flow actuator motor control waveform for face position to foot position – transition phase
Figure 42. Air flow actuator motor control waveform for face position to foot position – final phase
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
43
Testing and Measurements
Waveforms for temperature actuator motor control at different degree of coldness/hotness levels are
shown in Figure 43 and Figure 44.
Figure 43. Waveform when the degree of coldness is decreased
Figure 44. Waveform when the degree of coldness is increased
Automotive HVAC Control System with LCD Interface
44
Freescale Semiconductor, Inc.
Testing and Measurements
4.3. Temperature sensor
Waveform for the temperature sensor is shown in Figure 45 when the temperature on the sensor is
increased. The waveform is captured by bringing the solder rod @ 200°C close to the sensor for 2
seconds (approx).
Figure 45. Waveform for temperature sensor output when temperature is increased drastically from the
ambient temperature
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
45
Testing and Measurements
Appendix A
A.1
Schematic
Automotive HVAC Control System with LCD Interface
46
Freescale Semiconductor, Inc.
Testing and Measurements
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
47
Testing and Measurements
Automotive HVAC Control System with LCD Interface
48
Freescale Semiconductor, Inc.
Testing and Measurements
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
49
Testing and Measurements
Automotive HVAC Control System with LCD Interface
50
Freescale Semiconductor, Inc.
Testing and Measurements
A.2
Layout
A.2.1
Silkscreen Top
A.2.2
Silkscreen Bottom
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
51
Testing and Measurements
A.2.3
Top
A.2.4
Bottom
Automotive HVAC Control System with LCD Interface
52
Freescale Semiconductor, Inc.
Testing and Measurements
Appendix B
Bill of Material
Ite
m
Qu
an
tity
1
4
2
2
3
ASSY
_OPT
Reference
Value
Description
Mfg
Number
BH1,BH2,BH3,B
H4
MOUNTING
HOLE
MOUNTING HOLE DRILL 108
PAD 140 PLATED TH NO PART
TO ORDER
Mounting Hole
- 108mil Drill
PTH
BH5,BH6
MH_180
MOUNTING HOLE DRILL 135
PAD 180 PLATED TH NO PART
TO ORDER
Mounting Hole
- 135mil Drill
PTH
2
BH7,BH8
MH_180
MOUNTING HOLE DRILL 135
PAD 180 PLATED TH NO PART
TO ORDER
Mounting Hole
- 135mil Drill
PTH
4
12
C1,C18,C20,C2
3,C24,C33,C34,
C36,C37,C45,C
46,C51
0.01UF
CAP CER 0.01UF 50V 10% X7R
0805
C0805X7R50
0-103KNE
5
15
0.1 UF
CAP CER 0.1UF 50V 10% X7R
0805
C0805C104K
5RAC
6
1
C2,C6,C11,C13,
C14,C15,C16,C
17,C19,C27,C29
,C39,C41,C48,C
60
C3
1000PF
CAP CER 1000PF 50V 5% C0G
0805
C0805C0G50
0-102JNE
7
1
C5
1000UF
CAP ALEL 1000UF 50V 20% -RADIAL
UVZ1H102M
HD
8
1
C7
10UF
CAP TANT ESR=.125 OHMS
10UF 35V 10% 7343-31
TPSD106K03
5R0125
9
1
C8
68UF
CAP TANT ESR=0.045 OHMS
68UF 25V 10% -- 7343-43
TPME686K02
5R0045
10
2
C9,C10
47UF
CAP TANT 47UF 16V 10% -7343-31
293D476X901
6D2TE3
11
1
C12
10uF
CAP TANT 10uF 10V 10% -2013
T491R106K01
0AT
12
2
C21,C22
18PF
CAP CER 18PF 50V 5% C0G
0805
08055A180JA
T2A
DNP
Part
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
53
Testing and Measurements
13
4
C26,C28,C38,C
40
47UF
CAP ALEL
6.3X6.3X5.3
SM
MAL2153754
79E3
14
4
C30,C31,C42,C
43
0.033UF
CAP CER 0.033UF 50V 10%
X7R 0805
08055C333K
AT2A
15
4
C32,C35,C44,C
47
1uF
CAP CER 1uF 16V 10% X7R
0805
C0805C105K
4RAC
16
1
C49
10UF
CAP CER 10UF 16V 10% X5R
1210
1210YD106K
AT2A
17
1
C50
3.3 UF
CAP CER 3.3UF 10V +80%/20% Y5V 0805
C0805C335Z
8VAC
18
1
C52
0.1uF
CAP CER 0.10UF 50V 5% X7R
0805
MCCE104J2N
RTF
19
1
C53
0.047UF
CAP CER 0.047UF 50V 5% X7R
0603
GMC10X7R4
73J50NTLF
20
6
C54,C55,C56,C
57,C58,C59
0.1UF
CAP CER 0.10UF 25V 10% X7R
0603
C0603C104K
3RAC
21
1
DS1
GDC8799
LCD DISPLAY 5V CUSTOM TH
GDC8799
22
1
DS2
LX88461594
WS6
LCD BACK-LIGHT MODULE 3V
TH
LX88461594
WS6
23
2
D1,D2
B130LB-13
DIODE SCH RECT 1A 30V SMB
B130LB-13-F
24
1
D3
LED GREEN
LED GRN -- 25MA SMT 1206
APT3216SGC
25
1
D5
BAT54S
DIODE DUAL SCH 200MA 30V
SOT23
BAT54S
26
1
D6
BAT54S
DIODE DUAL SCH 200MA 30V
SOT23
BAT54S
27
8
D7,D8,D9,D10,
D11,D12,D13,D
14
LED_GRN +
ELECTROD
E
SUBASSEMBLY LED GRN SGL
20MA 1206 + RECTANGULAR
ELECTRODE 590X270MIL
510-77640,
370-76519
28
1
F1
Fuse Holder
FUSE CLIP,5X20
MOUNT
HTC-15M
29
2
JP1,JP4
HDR 1X1
HDR 1X1 TH -- 330H AU 100L
HTSW-10107-SM-S
30
3
JP2,JP3,JP5
HDR 1X1
HDR 1X1 TH -- 330H AU 100L
HTSW-10107-SM-S
31
1
J1
CON TB 2
CON 1X2 TB TH 200MIL SP
709H - 197L
1711725
DNP
DNP
47UF
50V
FUSE,PC
Automotive HVAC Control System with LCD Interface
54
Freescale Semiconductor, Inc.
Testing and Measurements
32
2
J2,J8
HDR 1X2
HDR 1X2 TH 100MIL SP 330H
SN 115L
TSW-102-07T-S
33
1
J3
HDR_1X4
HDR 1X4 TH 100MIL SP 336H
AU 100L
TSW-104-07G-S
34
2
J4,J13
HDR 2X3
HDR 2X3 TH 2.54MM SP 340H
AU 118L
M20-9980345
35
1
J5
CON_2X8
CON 2X8 PLUG SHRD TH
4.2MM SP 516H SN 140L
39-28-8160
36
2
J6,J11
HDR
TH
HDR 1X2 TH 100MIL SP 339H
AU 98L
TSW-102-07G-S
37
1
J7
HDR_1X4
HDR 1X4 TH 100MIL SP 336H
AU 100L
TSW-104-07G-S
38
1
J9
HDR 2X2
HDR 2X2 TH 2.54MM CTR
330H AU
TSW-102-07G-D
39
2
J10,J14
HDR
1X3
HDR 1X3 TH 100MIL SP 339H
AU 100L
TSW-103-07G-S
40
1
J12
HDR_2X5
HDR 2X5 TH 100MIL CTR 330H
AU
TSW-105-08G-D
41
1
L1
47UH
IND
PWR
47UH@100KHZ
1.65A 30% SMT
SRU1038470Y
42
1
L2
68UH
IND
PWR
68UH@100KHZ
2.22A 20% SMT
DR125-680-R
43
6
L3,L4,L5,L6,L7,
L8
330 OHM
IND
FER
BEAD
330OHM@100MHZ 2.5A -- SMT
MPZ2012S33
1A
44
2
L9,L10
BLM31AJ60
1SN1L
IND
FER
BEAD
600OHM@100MHZ 200MA 25%
1206
BLM31AJ601
SN1L
45
1
P1
CON_1_PW
R
CON 1 PWR PLUG RA TH 1A -430H NI
RAPC722X
46
1
Q1
BC857BLT1
TRAN PNP GEN 100MA 45V
SOT23
BC857BLT1G
47
4
Q2,Q3,Q5,Q6
BC847AL
TRAN NPN GEN 45VDC
BC847ALT1G
48
1
Q4
MGSF1N02
LT1G
TRAN NMOS PWR 750MA 20V
SOT-23
MGSF1N02LT
1G
49
1
R1
560
RES MF 560 OHM 1/8W 1%
0805
23227346560
1L
50
1
R2
0.01 OHM
RES MF 0.01 OHM 1/2W 1%
2010
WSL2010R01
00FEA
DNP
DNP
2010
1/2W
1X2
TH
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
55
Testing and Measurements
51
16
R3,R6,R7,R12,
R13,R18,R21,R
22,R35,R37,R51
,R52,R54,R59,R
61,R74
R4,R14,R36,R5
3,R62
10.0K
RES MF 10.0K 1/8W 1% 0805
CR0805-8W1002FT
52
5
100
RES MF 100 OHM 1/8W 5%
0805
RC73L2D101
JTF
53
8
R9,R10,R31,R3
2,R38,R39,R46,
R47
R11,R19
1.0K
RES MF 1.00K 1/8W 1% 0805
RK73H2ATTD
1001F
54
2
200
RES MF 200 OHM 1/8W 1%
0805
CR0805FX20
00ELF
55
3
R15,R16,R56
10.0K
RES MF 10.0K 1/8W 1% 0805
CR0805-8W1002FT
56
3
R17,R65,R73
4.7K
RES MF 4.7K 1/8W 5% 0805
CR0805-8W472JT
57
1
R20
1M
RES MF 1M 1/10W 5% 0805
RC73L2A105
JTF
58
2
R23,R25
1.0K
RES MF 1.00K 1/8W 1% 0805
RK73H2ATTD
1001F
59
10
0ohm
RES 0.0 OHM 1/8W 5% 0805
SMD
RC0805JR070RL
60
1
R24,R26,R27,R
28,R29,R40,R42
,R43,R45,R58
R30
270
RES MF 270 OHM 1/8W 1%
0805
MCR10EZHF
2700
61
3
DNP
R33,R41,R48
0ohm
RES 0.0 OHM 1/8W 5% 0805
SMD
RC0805JR070RL
62
3
DNP
R34,R44,R49
270
RES MF 270 OHM 1/8W 1%
0805
MCR10EZHF
2700
63
1
R50
2.2K
RES MF 2.2K 1/8W 5% 0805
CR0805-JW222ELF
64
1
R55
15.0K
RES MF 15.0K 1/8W 1% 0805
RK73H2ATTD
1502F
65
9
1.0K
RES MF 1.0K 1/8W 5% 0805
MCR10EZPJ1
02
66
1
R57,R66,R67,R
68,R69,R70,R71
,R72,R75
R60
15.0K
RES MF 15.0K 1/8W 1% 0805
RK73H2ATTD
1502F
67
2
R63,R64
60.4
RES MF 60.4 OHM 1/8W 1%
0805
23227346604
9L
68
1
SW1
EG1213
SW SPDT SLD RA 200MA 30V
TH
EG1213
69
1
U1
LM2676S5.0
IC VREG SWT 5V 3A 8.0-40V
TO-263
LM2676S5.0/NOPB
70
1
U2
MC9S12HY/
HA
IC MCU 16BIT 64K FLASH 4K
RAM 4.5-5.5V LQFP100
P9S12HY64J
0MLL
DNP
DNP
DNP
Automotive HVAC Control System with LCD Interface
56
Freescale Semiconductor, Inc.
Testing and Measurements
71
1
U3
LM94022
IC
MULTI-GAIN
ANALOG
TEMPERATURE SENSOR 1.55.5V SC70-5
LM94022BIM
GXNOPB
72
1
U4
TSOP34838
IC IR RCVR MODULE 38KHZ
2.5-5.5V TH
TSOP34838
73
2
U5,U6
MC33932
IC THROTTLE CONTROL DUAL
H-BRIDGE 8.0-28V HSOP44
MC33932VW
74
1
U7
MC33984CP
NA
IC LIN SW DUAL 4MILLIOHM 627V PQFN16
MC33984CPN
A
75
1
U8
TJA1040T
IC XCVR CAN HS 5V SO8
TJA1040T
76
1
U9
PC9S08PT6
0VLH
IC MCU 8BIT 60KB FLASH 4KB
RAM 20MHZ 2.7-5.5V LQFP64
PC9S08PT60
VLH
77
1
Y1
8MHz
XTAL 8MHz -- SMT
AT-51CD28.000M-STDPFE-2
Automotive HVAC Control System with LCD Interface
Freescale Semiconductor, Inc.
57
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© 2015 Freescale Semiconductor, Inc.
Document Number: DRM159
Rev 0
03/2015