AN10661 Brushless DC motor control using the LPC2141 Rev. 01 — 17 October 2007 Application note Document information Info Content Keywords LPC2148, ARM7, Brushless DC motor control Abstract This application note demonstrates the use of a low cost ARM7 based LPC2141 microcontroller for sensored brushless DC motor control. AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 Revision history Rev Date Description 01 20071017 Initial version. Contact information For additional information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 2 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 1. Introduction This application note demonstrates the use of a low cost NXP Semiconductors LPC2141 microcontroller for brushless DC motor control. It may be used as a starting point for motor control system designers using an NXP LPC2000 microcontroller. The LPC2141 is based on a 16/32-bit ARM7 CPU combined with embedded high-speed flash memory. A superior performance as well as their tiny size, low power consumption and a blend of on-chip peripherals make these devices ideal for a wide range of applications. Various 32-bit timers, 10-bit ADC and PWM features through output match on all timers, make them particularly suitable for industrial control. Main reason to use the LPC2141 for this reference design (see Fig 1) is the on-chip USB interface, which is used to communicate with a PC GUI (Graphical User Interface) controlling the motor. Besides the use of an LPC2141, the reference design in this application note shows a complete motor control system solution from NXP Semiconductors in terms of NXP Microcontroller – NXP MOSFET driver – NXP MOSFET. Brushless DC (Direct Current) motors are most commonly used in easy to drive, variable speed and long life applications. They have become widespread and are available in all shapes and sizes from large-scale industrial models to small motors for light applications (such as 12 V BLDC motors). Applications: Air conditioners, electric pumps, fans, printers, robots, electric bikes, -doors, -windows, sun roofs, -seats, mixers, food processors, blenders, vacuum cleaners, toothbrushes, razors, coffee grinders, etc. Gate driver PWM Signals Speed Command MOSFET driver Control uC Motor Sensors • Speed • Current • Position Fig 1. Controller (green) and Power (blue) demo boards for BLDC motor application AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 3 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 2. Brushless DC motor fundamentals Brushless DC motors consist of a permanent magnet rotor with a three-phase stator winding. As the name implies, BLDC motors do not use brushes for commutation; instead, they are electronically commutated. Typically three Hall sensors (see Fig 2) are used to detect the rotor position and commutation is based on these sensor inputs. Brushless DC (BLDC) motors are rapidly gaining popularity. They offer longer life and less maintenance than conventional brushed DC motors. Some other advantages over brushed DC motors and induction motors are: better speed versus torque characteristics, noiseless operation and higher speed ranges. And in addition, the ratio of torque delivered to the size of the motor is higher, making them useful in applications where space and weight are critical factors. In a brushless DC motor, the electromagnets do not move; instead, the permanent magnets rotate and the three-phase stator windings remain static (see Fig 2). This gets around the problem of how to transfer current to a moving rotor. In order to do this, the brush-commutator assembly is replaced by an intelligent electronic “controller”. The controller performs the same power distribution as found in a brushed DC motor, but is using a solid-state circuit rather than a commutator/brush system. The speed and torque of the motor depend on the strength of the magnetic field generated by the energized windings of the motor, which depend on the current through them. Therefore adjusting the rotor voltage (and current) will change the motor speed. Fig 2. Brushless DC motor AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 4 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 3. How to control a brushless DC motor 3.1 Rotation A BLDC motor is driven by voltage strokes coupled with the given rotor position. These voltage strokes must be properly applied to the active phases of the three-phase winding system so that the angle between the stator flux and the rotor flux is kept close to 90° to get the maximum generated torque. Therefore, the controller needs some means of determining the rotor's orientation/position (relative to the stator coils.) In our design we use Hall effect sensors (some use a rotary encoder, others sense the back EMF in the un-driven coils) to directly measure the rotor's position. Each sensor element outputs a high level for 180° of an electrical rotation, and a low level for the other 180°. The three sensors have a 60° relative offset from each other. This divides a rotation into six phases (3-bit code). Fig 3 and Fig 4 show the relationship between the Hall sensor input code and the required active motor windings. Commutator Armature Windings Q1 Q2 Hall Sensor code Phase # 101 1 Q1 (PWM1) Q6 (PWM6) 100 2 Q1 (PWM1) Q5 (PWM5) 110 3 Q3 (PWM3) Q5 (PWM5) 010 4 Q3 (PWM3) Q4 (PWM4) 011 5 Q2 (PWM2) Q4 (PWM4) 001 6 Q2 (PWM2) Q6 (PWM6) Q3 Three phase bridge Q4 Q5 Active drive Q6 Fig 3. Three phase bridge and sensor input by active switch table Vm Vm Vm PWM1 Q1 OFF Q2 OFF Q3 PWM1 Q1 OFF Q2 OFF Q3 OFF Q1 OFF Q2 PWM3 Q3 OFF Q4 OFF Q5 PWM3 Q6 OFF Q4 PWM5 Q5 OFF Q6 OFF Q4 PWM5 Q5 OFF Q6 Vm Vm Vm OFF Q1 OFF Q2 PWM3 Q3 OFF Q1 PWM2 Q2 OFF Q3 OFF Q1 PWM2 Q2 OFF Q3 PWM4 Q4 OFF Q5 OFF Q6 PWM4 Q4 OFF Q5 OFF Q6 OFF Q4 OFF Q5 PWM6 Q6 Fig 4. Motor rotation Q1 to Q6 switch sequence AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 5 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 3.2 Speed control By simply varying the voltage across the motor, one can control the speed of the motor. When using PWM outputs to control the six switches of the three-phase bridge, variation of the motor voltage can be achieved easily by changing the duty cycle of the PWM signal (see Fig 5). Vm duty cycle PWM1 Q1 Q2 Q3 Q4 Q5 Q6 Fig 5. PWM speed control 3.3 Motor feedback 3.3.1 Current sense Low cost motor current measuring can be implemented (like in this application note) using a current sensing resistor between the switching MOSFETs and ground (see also block diagram Fig 6). The small voltage appearing across the current sense resistor is filtered and amplified, before being fed to an ADC input of the microcontroller. Like in this application note measuring the motor current is often used as a safety. In case the motor is in a stalled position, the current will increase dramatically. Due to this exceptional increase in current, the ADC values will reach a current limit level that will cause the system to shut down, avoiding any damages (switch into ‘coast’ mode). 3.3.2 RPM measurement For closed loop speed control the ‘real’ motor speed must be known. By having the Hall sensor signals available at the LPC2141 microcontroller input pins, they can easily be “misused” for exact motor speed (RPM) measurement. One possible way for example is to connect the Hall sensor outputs to external interrupt input pins of the microcontroller. This results in having an interrupt every 60° degrees of an electrical rotation. By simply counting the number of interrupts within a certain exact time (for example 1 second) it’s easy to calculate the exact motor speed. Another possibility is to connect the sensor signals to Timer Capture inputs of the microcontroller. This way the exact time is measured between every rotation phase change. AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 6 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 4. Application setup FET drivers PWM PWM 12V PWM Q1 Q2 Q3 BLDC Motor M Q4 Q5 Q6 HALL Sensors PWM N S PWM S N PWM USB USB CAP CAP CAP GPI GPI GPI Gain Amp AIN Im LPC2141 Fig 6. Block diagram 4.1 Using the LPC2141 For this application note the LPC2141 is used (see Fig 6), mainly because of its sixchannel PWM timer and the on-chip USB interface. Available in an LQFP64 package it is a small and cheap member of NXP’s ARM7 based LPC2000 family. It offers high speed (60 MHz) 32-bit CPU performance, 8 kB of on-chip static RAM and 32 kB of on-chip flash program memory. For larger memory - or additional specific peripheral (CAN, Ethernet, etc.) requirements, a broad selection of (compatible) NXP - LPC2000 family members are available. To give an impression of the possibilities this microcontroller offers, for this application note: − CPU load is less than 5 %, used code size is 6 kB (including USB communication) − Unused peripherals: UART, I2C, SPI/SSP, RTC, 2 x Timer and 5 x A/D input − Over 30 unused GPIO pins available for user’s application 4.2 Motor selection For this application note a 120 W Maxon EC-40 motor is used. The ‘no-load’ speed is 5900 RPM at 24 V input. The maximum continuous current is 6 A. AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 7 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 4.3 MOSFET selection The NXP Semiconductors PH20100S N-channel TrenchMOS logic level FET is used for this system. It is chosen in relation with the selected motor, which is supplied with 24 V. For a 24 V - supplied motor, the MOSFET VDS needs to be at least 40 V, while the drain current needs to be high enough to deal with the motor (starting) current. The latter is already reduced thanks to a soft-acceleration mechanism (in small steps up towards the required speed) implemented in software. The PH20100S can deal with a maximum drain current of 34.3 Amps and a peak current of 137 Amps and is available in an SMD SOT669 (LFPAK) package (see Fig 7). 4.4 MOSFET driver selection MOSFET drivers are needed to raise the controller’s output signal (driving the MOSFET) to the motor supply voltage level. In this application note we selected the PMD3001D and the PMGD400UN from NXP Semiconductors, as shown in Fig 7. Vcc Dbst Cbst Qa M1 SOT669 (LFPAK) package To motor winding M1, M2 = 2 x LFPAK: PH20100S Qa, Qb = 2 x PMD3001D M1s = 1 x PMGD400UN Dbst = 1 x BAS16VY 3V6 PWM_HS Qb M1s M2 PWM_LS Fig 7. Simplified MOSFET – driver diagram for low and high side driver 4.5 Adjusting motor speed The LPC2141 has an on-chip six-channel (32-bit) PWM timer, which makes it ideal for using it to control a three-phase bridge. Values for desired motor speed are received via the USB interface AN10661_1 Application note © NXP B.V.2007. All rights reserved. Rev. 01 — 17 October 2007 8 of 18 32 28 64 24 56 52 60 20 47K 3V3 57 RSTn 100n P1.16 P1.17 P1.18 P1.19 P1.20 P1.21 P1.22 P1.23 33e 11 10 DD+ LPC2141 PWM4 / P0.8 PWM6 / P0.9 P0.10 P0.11 P0.12 P0.13 P0.14 P0.15 P0.16 P0.17 P0.18 P0.19 P0.20 PWM5 / P0.21 P0.22 P0.23 19 21 22 26 27 29 30 31 PWM_1 33 34 35 37 38 39 41 45 PWM_4 PWM_6 PWM_3 PWM_2 47K 3V3 46 47 53 54 55 1 2 58 HAL_A HAL_B HAL_C PWM_5 33e 18p 18p AD0.4 / P0.25 1K5 USB 6 3 2 5 4 1 CAP0.2 / P0.28 CAP0.3 / P0.29 CAP0.0 / P0.30 P0.31 LD1117S33 5V IN + 3V3 OUT GND 49 63 23 43 51 7 Imotor 9 13 14 15 17 Vbat Vref Vdd Vdd Vdd Vdda + 100n 10u 100n 100n 100n 10u XTAL1 Fig 8. Hardware schematics – controller part Vss Vss Vss Vss Vss Vssa XTAL2 62 61 12MHz RTXC1 RTXC2 3 5 22p 22p AN10661 9 of 18 © NXP B.V. 2007. All rights reserved. 6 18 25 42 50 59 Brushless DC motor control using the LPC2141 Rev. 01 — 17 October 2007 16 12 8 4 48 44 40 36 PWM1 / P0.0 PWM3 / P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 PWM2 / P0.7 P1.24 P1.25 P1.27 P1.26 P1.29 P1.30 P1.28 P1.31 NXP Semiconductors AN10661_1 Application note 5. Hardware schematics NXP Semiconductors AN10661_1 Application note 12 - 24V 5V BAS16 10K 100n 1K 10E Q1 PH20100S Q3 PH20100S 3V6 PMD3001D Q2 PH20100S 1K BAS21 Same as Q1 FET driver PWM_3 Same as Q1 FET driver PWM_2 PWM_1 W1 W2 W3 PMBF170 Hall Sensor 10K 10K 10E Q4 PH20100S Q6 PH20100S PMGD400UN PMD3001D PWM_4 Q5 PH20100S BAS21 + A B C - 5V HAL_A HAL_B HAL_C Same as Q4 FET driver PWM_6 Same as Q4 FET driver PWM_5 LM358 + 1K 100K 1K 10u + AN10661 10 of 18 © NXP B.V. 2007. All rights reserved. Fig 9. Hardware schematics – power / motor part BAS21 10K 100n 0.01E Imotor Brushless DC motor control using the LPC2141 Rev. 01 — 17 October 2007 5V Motor windings AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 6. Software The software for the complete demo contains three main parts: User Interface (GUI), USB driver and the Motor Control application code. 6.1 User interface A WindowsⓇ user interface is available to control the BLDC demo (see Fig 10). The program is called “BLDC_USBGUI.EXE” and is developed in Microsoft Visual Basic 2005 Express, so it needs the Microsoft .NET framework installed at your PC. The program offers easy control of speed and readouts of motor current and RPM. Fig 10. Windows user interface screen 6.2 USB device driver For USB communication Keil’s LPC2148 USB HID (human interface device) software example is used. For more information please check website of Keil. 6.3 BLDC Motor Control code The example software is written in C language and compiled using Keil’s uVision (ARM7 RealView, V3.0) free demo compiler. It performs following main tasks: • USB interface for receiving desired speed, sending motor current and measure and send calculated RPM • Read and ‘guard’ the motor current, using 10-bit ADC input • Use Timer 1 to generate a system-interrupt every 10 milliseconds. • Motor commutation by reading Hall sensors (using Timer 0 input capture pins), set the PWM Timer duty cycle for speed and drive Q1-Q6 MOSFET outputs for control of the three-phase bridge. AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 11 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 7. Source code listings The motor control part consists of five modules (bldc.c – adc.c – pwm.c – hsensor.c timer1.c) and a header file (bldc.h), all listed below. The USB modules from Keil’s HID example are not listed in this application note. For LPC2141 configuration the standard startup code from Keil was used and set as CCLK = PCLK = 60 MHz. 7.1 BLDC.C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 #include <LPC214x.H> #include "bldc.h" unsigned char actualSpeed = 0; unsigned char desiredSpeed = 0; unsigned int RPM,fRPM; void GetInReport(unsigned char *rep) { rep[0] = fRPM; rep[1] = fRPM >> 8; rep[2] = AD0DR4 >> 8;; } void SetOutReport(unsigned char *rep) { if (rep[0] < 101) desiredSpeed = rep[0]; } int main (void) { ADC0_Init(); T1_Init(); PWM_Init(); HES_Init(); USB_Init(); USB_Connect(1); while (1) { if (((AD0DR4 >> 8) & 0xFF) > MAX_Im) { VICIntEnClr = 0xFFFFFFFF; PWMMR1 = 0; PWMMR2 = 0; PWMMR3 = 0; PWMMR4 = 0; PWMMR5 = 0; PWMMR6 = 0; PWMLER = 0x7F; while (1) ; } AN10661_1 Application note // LPC214x definitions // Host is asking for an InReport // send measured motor speed (low byte) // send measured motor speed (high byte) // send potm value for debugging // OutReport received from USB host // New desired speed value received // ADC0 Initialization // 10 msec tick // PWM Timer Initialization // USB Initialization // USB Connect // Loop forever // Check motor overcurrent // // // // // // // // // disable all interrupts! Q1 off Q2 off Q3 off Q4 off Q5 off Q6 off enable PWM0-PWM6 match latch (reload) wait for a RESET © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 12 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 if (f_10ms) { f_10ms = 0; // every 10 mseconds if (actualSpeed > desiredSpeed) actualSpeed --; else if (actualSpeed < desiredSpeed) actualSpeed ++; RPM = 10000000 / T0CR0; fRPM = ((fRPM * 15) + RPM) / 16; // calculate motor speed // filter it } } } 7.2 ADC.C 1 2 3 4 5 6 7 8 #include <LPC214x.h> void ADC0_Init(void) { PINSEL1 |= 0x00040000; AD0CR = 0x00200F10; AD0CR |= 0x00010000; } // P0.25 = AIN0.4 // initialise ADC0, select AIN4 // start burst mode now, see errata ADC.2 7.3 PWM.C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 #include <LPC214x.h> void PWM_Init(void) { PINSEL0 |= 0x000A800A; PINSEL1 |= 0x00000400; PWMPR = 20; PWMPC = 0; PWMTC = 0; PWMMR0 = 100; PWMMR1 = 0; PWMMR2 = 0; PWMMR3 = 0; PWMMR4 = 0; PWMMR5 = 0; PWMMR6 = 0; PWMMCR = 0x00000002; PWMPCR = 0x7E00; PWMLER = 0x7F; PWMTCR = 0x09; // select PWM1-4 and PWM6 // select PWM5 // // // // // // // // // // // // // // prescaler to 20, timer runs at 60 MHz / 20 = 3 MHz prescale counter to 0 reset timer to 0 -> PMW base frequency = 3 MHz / 100 = 30 KHz Match 1 for Q1 (off) Match 2 for Q2 (off) Match 3 for Q3 (off) Match 4 for Q4 (off) Match 5 for Q5 (off) Match 6 for Q6 (off) reset TC on MR0 enable PWM1 - PWM6 outputs enable PWM0 - PWM6 match latch (reload) enable PWM mode and start timer } AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 13 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 7.4 HSENSOR.C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 #include <LPC214x.H> #include "bldc.h" __irq void T0_Isr(void) { T0TC = 0; switch ((IO0PIN >> 18) & 7) { case 1: PWMMR1 = actualSpeed; PWMMR2 = 0; PWMMR3 = 0; PWMMR4 = 0; PWMMR5 = 0; PWMMR6 = actualSpeed; break; case 2: PWMMR1 = 0; PWMMR2 = actualSpeed; PWMMR3 = 0; PWMMR4 = actualSpeed; PWMMR5 = 0; PWMMR6 = 0; break; case 3: PWMMR1 = 0; PWMMR2 = actualSpeed; PWMMR3 = 0; PWMMR4 = 0; PWMMR5 = 0; PWMMR6 = actualSpeed; break; case 4: PWMMR1 = 0; PWMMR2 = 0; PWMMR3 = actualSpeed; PWMMR4 = 0; PWMMR5 = actualSpeed; PWMMR6 = 0; break; case 5: PWMMR1 = actualSpeed; PWMMR2 = 0; PWMMR3 = 0; PWMMR4 = 0; PWMMR5 = actualSpeed; PWMMR6 = 0; break; case 6: PWMMR1 = 0; PWMMR2 = 0; PWMMR3 = actualSpeed; PWMMR4 = actualSpeed; PWMMR5 = 0; // LPC214x definitions // Reset timer // read Hall sensor inputs P0.18, P0.19 and P0.20 // phase 6: 001 // phase 4: 010 // phase 5: 011 // phase 2: 100 // phase 1: 101 // phase 3: 110 AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 14 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 PWMMR6 = 0; break; default: break; // invalid } T0IR = 0xFF; PWMLER = 0x7F; VICVectAddr = 0; // reset flags // enable PWM0 - PWM6 match latch (reload) // Acknowledge interrupt by reseting VIC } void HES_Init(void) { VICVectAddr1 = (unsigned int) &T0_Isr; VICVectCntl1 = 0x24; // Channel1 on Source#4 ... enabled VICIntEnable |= 0x10; // Channel#4 is the Timer 0 PINSEL1 |= 0x3A000000; // P0.30,P0.28,P0.29 as CAP0.0,CAP0.2,CAP0.3 T0PR T0MR0 T0MCR T0CCR T0TC T0TCR // pre 60, timer runs at 60 MHz / 60 = 1 MHz // = 1 sec / 1 us = = = = = = 60; 1000000; 3; 0x0FC7; 0; 1; // Capture on both edges and enable the interrupt // Reset timer // start timer } 7.5 TIMER1.C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 #include <LPC214x.H> // LPC214x definitions char f_10ms = 0; __irq void T1_Isr(void) { f_10ms = 1; T1IR = 0x01; VICVectAddr = 0; } // Timer 1 ISR every 10 msec // toggles every 10 mseconds // reset interrupt flag // reset VIC void T1_Init(void) { VICVectAddr2 = (unsigned int) &T1_Isr; VICVectCntl2 = 0x25; // Channel2 on Source#5 ... enabled VICIntEnable |= 0x20; // Channel#5 is the Timer 1 T1MR0 = 600000; T1MCR = 3; T1TC = 0; T1TCR = 1; // // // // // = 10 msec / 16,67 nsec Interrupt on Match0, reset timer on match Pclk = 60 MHz, timer count = 16,67 nsec reset Timer counter enable Timer } AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 15 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 7.6 BLDC.H 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #define MAX_Im 0xF0 // max motor current limit extern unsigned char actualSpeed; extern extern extern extern void void void void GetInReport(unsigned char *rep); SetOutReport(unsigned char *rep); USB_Init(void); USB_Connect(unsigned int con); extern void ADC0_Init(void); extern void PWM_Init(void); extern void HES_Init(void); extern void T1_Init(void); extern char f_10ms; AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 16 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 8. Legal information 8.1 Definitions Draft — The document is a draft version only. The content is still under internal review and subject to formal approval, which may result in modifications or additions. NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information. 8.2 Disclaimers General — Information in this document is believed to be accurate and reliable. However, NXP Semiconductors does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. Right to make changes — NXP Semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof. Suitability for use — NXP Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of a NXP Semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. NXP Semiconductors accepts no liability for inclusion and/or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and/or use is for the customer’s own risk. Applications — Applications that are described herein for any of these products are for illustrative purposes only. NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. 8.3 Trademarks Notice: All referenced brands, product names, service names and trademarks are property of their respective owners. AN10661_1 Application note © NXP B.V. 2007. All rights reserved. Rev. 01 — 17 October 2007 17 of 18 AN10661 NXP Semiconductors Brushless DC motor control using the LPC2141 9. Contents 1. 2. 3. 3.1 3.2 3.3 3.3.1 3.3.2 4. 4.1 4.2 4.3 4.4 4.5 5. 6. 7. 7.1 7.2 7.3 7.4 7.5 7.6 8. 8.1 8.2 8.3 9. Introduction .........................................................3 Brushless DC motor fundamentals ...................4 How to control a brushless DC motor ...............5 Rotation .................................................................5 Speed control ........................................................6 Motor feedback......................................................6 Current sense........................................................6 RPM measurement ...............................................6 Application setup ................................................7 Using the LPC2101 ...............................................7 Motor selection ......................................................7 MOSFET selection ................................................8 MOSFET driver selection ......................................8 Controlling speed and direction .............................8 Hardware schematics .........................................9 Software .............................................................11 Source code listings .........................................12 BLDC.C ...............................................................12 ADC.C .................................................................13 PWM.C................................................................13 HSENSOR.C .......................................................14 TIMER1.C............................................................15 BLDC.H ...............................................................16 Legal information ..............................................17 Definitions............................................................17 Disclaimers..........................................................17 Trademarks .........................................................17 Contents.............................................................18 Please be aware that important notices concerning this document and the product(s) described herein, have been included in the section 'Legal information'. © NXP B.V. 2007. All rights reserved. For more information, please visit: http://www.nxp.com For sales office addresses, email to: [email protected] Date of release: 17 October 2007 Document identifier: AN10661_1