Instruction/ maintenance manual of the product DRM079 Freescale Semiconductor
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RS08 Micr ocontr oller s freescale.com DRM079 Rev. 0 5/2006 Designer Reference Manual Variable Speed DC Fan Control using the MC9RS08KA2.
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V ariable Speed DC F an Control using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 3 Variable Speed DC Fan Control using the MC9RS08KA2 Designer Reference Manual by: Vincent Ko Freescale Semiconductor, Inc. Hong Kong To provide the most up-to-date information, the revisi on of our docume nts on the World Wide Web will be the most current.
Revision History V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 4 Freescale Semiconductor.
V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 5 Table of Contents Chapter 1 Introduction 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 6 Freescale Semiconductor.
V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 7 Chapter 1 Introduction 1.1 Introduction This document describes the imp lementation of a DC brushless fan controller using the Freescale ultra low cost MC9RS08KA2 8-bit microcontroller (MCU).
Introduction V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 8 Freescale Semiconductor 1.2 Freescale’s New Genera tion Ultra Low Cost MCU The MC9RS08KA2 microcontroller unit (MCU) is an extremely low cost, small pin count device for home appliances, toys, and small g eometry applications, such as a DC fan controller.
Bi-Phase BLDC Motor V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 9 1.4 Bi-Phase BLDC Motor The brushless DC motor (BLDC) design for DC fan is commonly consist of a permanent magnet attached on the rotor and the stator phase co il windings are mounted on the moto r shaft as illustrated in Figure 1-2 .
Introduction V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 10 Freescale Semiconductor.
Commutation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 11 Chapter 2 Motor Control 2.1 Commutation The typical bi-phase BLDC has one pole-pair per phase. Each commuta tion rotates the rotor by 90 degrees and four commutation ste ps complete a mechan ical revolution.
Motor Control V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 12 Freescale Semiconductor 2.3 Commutation Waveforms In general, in a bi-phase motor design, alternate co ils are tied together and give a single connection to the driver. In this design, the driver conne ction for coil A and coil C is called L1 (see Figure 2-1 ).
Motor Startup V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 13 Dramatic changes in the dead-time val ue will cause the motor to stall. In this design a software loop in the MCU will control the dead-time variation.
Motor Control V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 14 Freescale Semiconductor.
Block Diagram V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 15 Chapter 3 Implementation 3.1 Block Diagram The block diagram of the DC fan design is illustrated in Figure 3-1 . A 12V low cost bi-phase BLDC motor is used in this application.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 16 Freescale Semiconductor Hall sensor output is conn ected to the MCU’s GP IO port, PTA2, wh ich has a programmable edge trigger keyboard interrupt (KBI). The programmable e dge trigger feature provides an effective way to monitor the Hall sensor signal.
Control Loop V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 17 Figure 3-2. Firmware Control Loop START TargetPWMPeriod = L ongest ActualPWMPeriod = Longest Drive L1 De-energized coils = DeadTime Drive L2 Read Temp.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 18 Freescale Semiconductor 3.4 Temperature Sensor Measurement The temperature sensor measurement is perfo rmed based on the methodology of an emulated ADC described in the applica tion note, AN3266 “Getting Started with RS08”.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 19 Table 3-2 shows the entire dynamic range of the temper ature sensor voltage can be covered by about 44 timer counts.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 20 Freescale Semiconductor As described in the previous section the ove rall dead-time duration should be deterministic, the double WAIT statements in the sub routine can ensure the execution time to be mostly constant.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 21 T able 3-3. T emperature Conver sion T able Temperatu re (°C) Channel Resistan ce (k Ω ) (from sensor data sheet) Voltage across Sensor (V) Predefined Motor Speed (rpm) Target PWM Period (Timer Counts (1) ) NO TES: 1.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 22 Freescale Semiconductor.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 23 Appendix A. Schematic R2 1 2 10K 220 R1 1 2 C2 1 2 2u2F/25V C3 1 2 2u2F/25V R8 .
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 24 Freescale Semiconductor.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 25 Appendix B. Program Listing ;************************************************************** ; ; (c) copyright Freescale Semiconductor.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 26 Freescale Semiconductor MTIM_TCLK_FALLING equ $20 MTIM_TCLK_RISING equ $30 ;===========================================.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 27 TargetPeriod ds.b 1 ActualPeriod ds.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 28 Freescale Semiconductor sta KBIES ;HALL rising Edge Trigger sta KBIPE ;KBI Enable ;------------------------------------------------------- ;Config MTIM ; ;Timer prescalar=256 -> Timer clk = 16kHz ;Bus = 4MHz ;Max OF period = 16.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 29 ;5) Read Temp Sensor Again bsr ReadSensor ; Read Sensor value ;6) Dead time con.
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 30 Freescale Semiconductor ; X indicate the coil to be driven ;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%.
Temperature Sensor Measurement V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 Freescale Semiconductor 31 NoReading: mov #$00, SensorReading ; Smallest Number clr ACMPSC ; disable ACMP .
Implementation V ar iable Speed DC Fan Contr ol using the MC9RS08KA2, Rev . 0 32 Freescale Semiconductor lda #255 Quiet: bclr BUZZER, PTAD ; Clear buzzer mov #30, MTIMMOD mov #(mMTIMSC_TRST|mMTIMSC_TO.
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