Renesas RL78G14 Installation and operating instructions

APPLICATION NOTE
RESH-OS-MC-20001 Rev.1.00 Page 1 of 26
Nov 03,2011
RL78/G14
Power Tool 120 deg. Reference Development
Introduction
This document will provide an overview of power tool 120 degree reference development. This solution is based on
Renesas Electronics' next-generation MCU (RL78 family), which combines advanced features from both the 78K and
R8C families. Same as mainstream power tool products in market, BLDC control is used in this solution.
Target Device
RL78/G14 Group
Contents
1. Overview ........................................................................................................................................... 2
2. System Diagram................................................................................................................................ 3
3. Configuration of R5F104BE .............................................................................................................. 4
4. Control theory.................................................................................................................................... 9
5. Hardware structure.......................................................................................................................... 13
6. Hardware and test data................................................................................................................... 19
7. Software flowchart........................................................................................................................... 22
APPENDIX .............................................................................................................................................. 25
RESH-OS-MC-20001
Rev.1.00
Nov 03, 2011

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1. Overview
1.1 Overview
120 degree control method are widely used in power tool controller, this kind of control mode not only include the
torque variation caused by phase change, but also include the torque variation caused by the step performance caused by
the control theory itself. This project adopts new method to overcome the torque variation on the basis of 120 control
mode.
The RL78 Family is Renesas Electronics' next-generation microcontroller family combining advanced features from
both the 78K and R8C families to deliver low power consumption and high performance. As one member of RL78
family, RL78/G14 achieves reduced system power consumption overall, and supports multifunctional consumer and
industrial applications without requiring additional external components. Since there is built-in three-phase PWM
output timer and two-phase encoder timer: Motor control, it is suitable to be used for Brushless DC motor control.
RL78/G14 is used to develop the 120 degree control method for the power tool controller. The main functions are list
below:
●120 degree sinusoidal wave control;
●Close-loop control of current;
●Three-step speed control;
●Over current protection;
●Thermal protection;
1.2 Electrical Specifications
Size: 50mm(L)*46.8mm(W)
Storage Environment: -20 ~ 85 ℃，40% ~ 95% RH
Operation Environment: 0 ~ 70 ℃，40% ~ 95% RH
Rated Voltage: DC 14V
Rated Current: 3.5A
Rated Power: 50W
Speed: High level: 0～2400 RPM
Middle level: 0～1800 RPM
Low level: 0～1100 RPM

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2. System Diagram
Figure 2-1 120 degree control system diagram
VDD=14.4V
BLDC
LM317
+
5V
RL78/G14
R5F104BE
Driver IC
L6387
Speed set
Direction set
LED lighting
…………
Strength set
LED Indication

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3. Configuration of R5F104BE
3.1 Pin of R5F104BE
Figure 3-1 Pin of R5F104BE

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3.2 Structure of R5F104BE
Figure 3-2 Structure of R5F104BE

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3.3 Function list of R5F104xx
Table 3-1 Function List
Item R5F104Ax R5F104Bx R5F104Cx R5F104Ex
Pin Count 30 32 36 40
Flash memory
(KB)
16 to 64 16 to 64 16 to 64 16 to 64
RAM (KB) 2.5 to 5.5 2.5 to 5.5 2.5 to 5.5 2.5 to 5.5
Internal
memory
Data Flash (KB) 4 4 4 4
Memory Space 1MB
High-speed
system clock
X1 (crystal/ceramic) oscillation, external main system clock
input (EXCLK)
1 to 20 MHz: VDD = 2.7 to 5.5 V, 1 to 8 MHz: VDD = 1.8 to
2.7 V, 1 to 4 MHz: VDD = 1.6 to 1.8 V
Main
system
Clock
（Oscillation
frequency
）
Internal high-
speed
oscillation
clock
Internal oscillation
64 MHz/48 MHz/32 MHz/24 MHz/16 MHz/12 MHz/8 MHz/4
MHz/1 MHz (TYP.)
Internal low-speed oscillation
clock
(For WDT)
Internal oscillation (Watchdog timer, Real-time clock,
Interval timer clock)
15 kHz (TYP.): VDD = 1.6 to 5.5 V
General-purpose register 8 bits 32 registers (8 bits 8 registers 4 banks)
0.03125 μs (Internal high-speed oscillation clock: fIH = 32
MHz operation)
0.05 μs (High-speed system clock: fMX = 20 MHz
operation)
Minimum instruction
execution time
30.5 μs (Subsystem clock: fSUB = 32.768 kHz operation)
Instruction set • 8-bit operation, 16-bit operation
• Multiplication (8 bits × 8 bits, 16 bits × 16 bits), Division (16
bits ÷ 16 bits, 32 bits ÷ 32 bits)
• Product-sum operation (16 bits × 16 bits + 32 bits)
• Bit manipulation (Set, reset, test, and Boolean operation),
etc.
I/O port
30-pin
produc
ts
32-pin
produc
ts
36-pin
produc
ts
40-pin
product
s
Total 26 28 32 36
CMOS I/O 21 22 26 28
CMOS input 3 3 3 5
CMOS output - - - -
N-ch open-drain
I/O
(6 V tolerance
2 3 3 3

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Timer
Timer
outputs
• 16-bit timer: 8 channels
• Watchdog timer: 1 channe
• Real-time counter: 1 channel
• Interval timer: 1 channel
A/D converter 8/10-bit resolution 8 channels
Serial interface [30-pin, 32-pin products]
• CSI: 1 channel/UART: 1 channel/simplified I2C: 1 channel
• CSI: 1 channel/UART: 1 channel/simplified I2C: 1 channel
• CSI: 1 channel/UART (UART supporting LIN-bus): 1
channel/simplified I2C: 1 channel
[36-pin, 40-pin products]
• CSI: 1 channel/UART: 1 channel/simplified I2C: 1 channel
• CSI: 1 channel/UART: 1 channel/simplified I2C: 1 channel
• CSI: 2 channels/UART (UART supporting LIN-bus): 1
channel/simplified I2C: 2 channels
Multiplier/divider • 16 bits × 16 bits = 32 bits (Unsigned or signed)
• 16 bits ÷ 16 bits = 16 bits, 32 bits ÷ 32 bits = 32 bits
(Unsigned)
• 16 bits × 16 bits + 32 bits = 32 bits (Unsigned or signed)
Data transfer controller
(DTC)
29 sources
Internal 24Vector
interrupt
source External 7
Reset • Reset by RESET pin
• Internal reset by watchdog timer
• Internal reset by power-on-reset
• Internal reset by voltage detector
• Internal reset by illegal instruction execution Note
• Internal reset by RAM parity error
• Internal reset by illegal-memory access
Voltage detector When voltage rises: between 1.63 V and 3.98 V (14 stages)
When voltage drops: between 1.67 V and 4.06 V (14 stages)
Power supply voltage VDD = 1.6 to 5.5 V
Operating ambient
temperature
TA = -40 to +85 C

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3.4 Pin function of R5F104BE
Table 3-2 Pin Function Configuration
Pin NO. Pin name Pin Function Note
1 P40/TOOL0 Program interface Input/Ouput
2 RESET Reset Input
3 P137/INTP0 AD analog input over-current
protection
4 P122/X2/EXCLK Not used
5 P121/X1 Not used
6 REGC Group via cap
7 VSS Group
8 VDD Power
9 P60/SCLA0 Direction control Input
10 P61/SDAA0 Strength indication 3 output
11 P62/SSI00 Strength indication 2 output
12 P31/TI03/TO03/INTP4/PCLBUZ0 Strength indication 1 output
13 P70 unused
14 P30/INTP3/SCK00/SCL00/TRJO0 HALL W Input
15 P50/INTP1/SI00/RxD0/TOOLRxD/SDA00/
TRGIOA HALL U Input
16 P51/INTP2/SO00/TxD0/TOOLTxD/TRGIO
B HALL V Input
17 P17/TI02/TO02/TRDIOA0/TRDCLK0 LED Lighting For lighting
18 P16/TI01/TO01/INTP5/TRDIOC0 Tact Switch Input
19 P15/PCLBUZ1/SCK20/SCL20/TRDIOB0 Drive of U High PWM output
20 P14/RxD2/SI20/SDA20/TRDIOD0 Drive of U Low PWM output
21 P13/TxD2/SO20/TRDIOA1 Drive of V High PWM output
22 P12/SO11/TRDIOB1 Drive of W High PWM output
23 P11/SI11/SDA11//TRDIOC1 Drive of V Low PWM output
24 P10/SCK11/SCL11/TRDIOD1 Drive of W Low PWM output
25 P147/ANI18 AD analog input Speed control
26 P23/ANI3 AD analog input Over-current
protection
27 P22/ANI2 AD analog input Thermal protection
28 P21/ANI1/AVREFM Not used
29 P20/ANI0/AVREFP AD power reference
30 P01/ANI16/TO00/RxD1/TRGCLKB/TRJIO
0 Failure indication Output
31 P00/ANI17/TI00/TxD1/TRGCLKA Tact switch
32 P120/ANI19 Battery check

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4. Control theory
4.1 Basic control theory of BLDC
The motors used in most power tool are Brushless DC motor, which the rated power is commonly very low. External
rotor structure is usually adopted to drive the power tool directly, but the power is very low because of its low rated
speed. Which cause the motor much bigger than other types of motor which have the same power value.
BLDC motor consists of motor, position sensor and electrical circuit. The stator is often made of several phases (such as
3 phases, four phases and five phases etc.), the rotor is consists of permanent magnet which arranged with different pole
pairs. Figure 4-1 shows a three phases, two poles BLDC motor.
3
2
1
电
源位置
传
感器
电子开关
电机本体
''
Figure 4-1 Structure of three phases, two poles BLDC motor
Three stator coils are connected with correspondent power devices in electrical circuit, A, B, C phase coils each
connected with power switch V1, V2, V3. Position sensors are used to detect the rotor position.
When one of the stator coils are power on, the current will cause torque by the interaction with magnetic field caused by
the rotor permanent magnetism, and the torque will cause the rotor running, the rotor position will be converted to
electrical signal by position sensors to control the electrical switches, thus make the each coils of stator are switched on
sequentially, the stator phase current will also change sequentially according to the position of rotor. Because of the
power on sequence of electrical switches are synchronous with the rotor angle, thus cause the same effect of mechanical
phase change.
Figure 4-2 shows the theory diagram of the half-bridge control of three phases, two poles BLDC motor. Photo-electric
devices are use as the position sensors. The power logic unit consists of three power MOSFET. The control theory will
be discussed below according to the half-bridge control.
Power
Motor
Hall sensors
Electrical switch

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2
3
1
'
'
电
源
123
Figure 4-2 Three phase brushless motor
The discrepancy of space position of three photo-electrical devices VP1、VP2 and VP3 are 120 degree each. Via the
function of photo-electrical, the rotor position can be achieved.
'
'
'
'
'
'
'
'
a) b) c) d)
Figure 4-3 Commutation sequence and the rotation of magnetic field
The rotor position of figure 4-2 is same as that of figure 4-3a). at this position, the power MOSFET V1 is switched on
and the current flows into coil A-A’, the torque caused by the interaction between the coil current and rotor magnetic
will make the rotor rotate as the direction shown in figure 4-3b). when the rotor locate at the position as in figure 4-
3b), the power MOSFET V1 will be switched off and V2 will be switched on, the current will be changed form coil
A-A’ to B-B’, and the rotor will continue to rotate as the direction shown in figure 4-3b). When the rotor reaches the
position shown as in figure 4-3c), the power MOSFET V2 will be switched off and V3 will be switched on，the
current will be flowed through C-C’，thus the rotor will continue rotate to the position shown in figure 4-3a).
With the change of position sensor signal, the stator coil will be switched on and off sequentially, then the phase
current will be changed sequentially. During the phase change period, the rotating magnetic field generated by the
coils of the stator is not continuous. This kind of rotating magnetic field has three state in 360 degree range, each
state lasts 120 degree. The relationship between each coil and rotor magnetic field are showed in figure 4-3. Figure 4-
3a）is the first state, Fa is the magnetic force generated by coil A-A’, then the interaction between the coil current
and rotor magnetic field will make the rotor rotate clockwise. After 120 degree，the rotor will be in the second state,
the coil A-A’ will be switched off and coil B-B’ will be switched on，the magnetic field generated by stator coil
rotate 120 degree range shown as in figure 4-3b）, and the motor rotor continue to rotate clockwise. After another
Power

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120 degree，the third state. the coil B-B’ will be switched off and C-C’ will be switched on, the magnetic field
generated by stator coil rotate another 120 degree, shown in figure 4-3c）. It will make the rotor rotate 120 degree
and then get the initial position. Figure 4-4 shows the switch on sequence of each coil.
¦Ψ
¦Ψ
¦Ψ
480
360
240120
0
-'
-'
-'
Figure 4-4 the switch on sequence of each coil
The electrical circuit of three phases, half-control bridge is simple. But the efficiency of the motor is very low because
the switch on time of each phase is only 1/3 of the total time. And during the control period, the variation range of
torque is very high, from Tm/2 to Tm. So in most circuits the three phases, full-control circuit is adopted.
4.2 Introduction of Three-phase, full-control theory of Y connection motor
Figure 4-5 show s a three-phase, full-control circuit, the motor is Y connection motor. VT1、VT2、VT3、VT4、VT5、
VT6 are power MOSFET, used to control the current of each phase. The control methods include 120 degree control
mode and 180 control mode.
Figure 4-5 Three-phase, full-control circuit for Y connection
4.3 120 degree control mode
120 degree control mode means there are two power MOSFETs are switched on at each moment, one power MOSFET
will be changed to another each 1/6 period, each power MOSFET will be switched on for 120 degree. The sequence of
all the power MOSFETs is VT1VT2、VT2VT3、VT3VT4、VT4VT5、VT5TF6、VT6VT1、···. When VT1 and
VT2 are switched on，the current flow into coil A from VT1 and out coil C from VT2, then to the power. Assume the
torque is positive when the current flows into a coil A, then the torque will be negative when the current flows out one
VT2VT6
VT4
VT1VT3VT5A B
C
+
US
-

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phase, so the synthesis torque are shown in figure 4-6a)，and the amplitude is a
T3, the direction locates at the
angular bisector of a
Tand c T−. Figure 4-6c) shows the direction of all the synthesis torque.
a) b) c)
Figure 4-6 The synthesis torque of 120 degree control mode
To one BLDC motor, the synthesis torque of 120 degree control is 3times bigger than that of half-bridge control.
The output torque are shown if figure 4-7, we can see that the variation range of the synthesis torque is between
m
T87.0 and m T.
Figure 4-7 Output torque of 120 degree control

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5. Hardware structure
5.1 Power and power detection
Figure 5-1 shows the structure of power and power detection circuit.
Figure 5-1 Power block diagram
5.1.1 Function description
The power of power tool are supply with battery, the battery in this solution are 14.4V.
14.4V voltage is supplied to driver ICs and power MOSFETs, by controlling the duty cycle of drive signal of power
MOSFET, the current will be controlled thus control the speed of the motor.
To avoid the over-discharge of the battery, the voltage of the battery need to be detected and switch off the power
MOSFETs when the voltage lower than 12V to protect the battery.
5V voltage is created by LM317 from 14.4V conversion, it is used to power MCU and other logic control circuit, so it is
also critical and need to be monitored.
Figure 5-2 +5V creation
VCC in figure 5-2 is the battery power 14.4V, R49 is protection resister, used to reduce the voltage input to LM317T,
then reduce the power consumption of LM317. LM317 is a chip used to regulate voltage, its output is set to 5V。
Voltage detection
Battery
（14.4V）
Power Conversion
Power drive
5V MCU & control
Motor
MCU Reset

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5.1.2 Voltage detection circuit
Figure 5-3 Battery voltage detection
Since the tolerance of MCU AD analog input cannot exceed 6V while VCC normally is more than 14V, we cannot
monitor VCC directly, so we use a voltage divider circuit to satisfy the tolerance. The battery voltage can be monitored
by sampling the divided voltage which is input to built-in AD module of MCU, in case the battery voltage is lower than
the pre-set threshold value, software will execute related behavior.
Figure 5-4 +5V detection
M51951 is integrated circuits designed for designed for detecting supply voltage and resetting logic circuits such as
CPUs. Normally when +5V voltage is lower than 4.2V by due to exceptional situation during system operating,
M51951 will output a valid signal(low) to reset MCU.
5.2 HALL signal detection
The HALL signal detection module is shown as the figure below:
Figure 5-5 Hall input block
5.2.1 Function description
HALL signal detection circuit used to get the rotor position, three hall signals are input to the interrupt input interface.
During 180 degree control, the speed and detailed angular also can be achieved via HALL signals.
5.2.2 HALL signal detection circuit
BLDC
HALL U
HALL V
HALL W
Signal converter
MCU
VCC
MCU AD Input
R6
4.
7K
R10
1
K
INTP
INTP
INTP

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Figure 5-6 Hall input circuit
5.3 LED Indication
5.3.1 Function description
As a part of interface between the power tool and user, LED can indicate the system operating status.
5.3.2 Circuit
Figure 5-7 LED indication
In this application, we use 4 LEDs , LED1~LED3 are used to indicate strength level, while LED4 is used for system
fault indication.
5.4 Switch setting
5.4.1 Function description
Several switches are used for system setting, such as strength level setting, LED lighting setting and direction setting.
5.4.2 Circuit
(1) strength level and LED lighting setting
Motor MCU

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Figure 5-8 Strength level and LED lighting control
In this circuit, we use 2 tact switch: S2 and S3. S2 is used for strength level while S3 for LED lighting.
The strength level of the power tool is divided 3 levers: weak level, middle level and strong level, the strength level can
be modified by pressing the S2.
We add white-LED lighting circuit in order to use the power tool in dark environment, the white-LED can be switch on
or off by pressing S3.
(2) CW/CCW Rotation Control
Figure 5-9 CW and CCW rotation control
CN4 is a self-locking switch and is used to control CW/CCW rotation.
5.5 Power and power drive
5.5.1 Function description
Power drive circuit used to convert the control signal of MCU to drive signal of MOSFET, by controlling the state of
each MOSFET, the current of the motor can be controlled.
The dead time of the two MOSFETs of each phase should be bigger than the time needed to switch off a MOSFET.
5.5.2 Circuit of power drive

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Figure 5-10 Motor driver circuit
Figure 5-10 shows the circuit of the whole 3 phase.
Compare to traditional circuit using discreet components for power drive, the above circuit use a integrated driver IC
L6387, the circuit can make the system more reliable and reduce the components.
5.6 Current sampling and protection circuit
5.6.1 Function description
Current sampling circuit used to current control and current protection. Actual value of the current can be achieved by
AD module, thus current close-loop control can be realized. Current protection can be realized by internal circuit.
5.6.2 Current sampling circuit

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Figure 5-11 Operational amplifier circuit
R18 on figure in part 5.5 is a current-sampling resistor, due to the amplitude of ibus is too small to be detected by AD
module in MCU, we need to use a operational amplifier LM358 to amplify ibus, the circuit as showed above. LM358 is
a dual operational amplifiers, we use input A to amplify ibus, the other amplifier input B is used to be a Comparator to
compare the amplified signal OC with pre-set voltage.
5.7 Thermal protection
5.7.1 Function description
The current consumption probably is close to 4A while the size of PCB is small, it is necessary to implement thermal
protection in circuit.
5.7.2 Thermal protection circuit
Figure 5-12 Thermal protection circuit
The figure 5-12 shows thermal protection circuit, OT is the signal which is connected to AD analog input. If the
temperature of the PCB board increase, the resistance of NTC1 will decrease, thus AD module can sample the OT
variation.

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6. Hardware and test data
6.1 Specifications of BLDC Motor
The technical data of the motor are as follows:
Rated Voltage: 14.4V
Rated Current: 3.5A
Rated Power: 50W
Speed: High level: 0～2400 RPM Middle level: 0～1800 RPM Low level: 0～1100 RPM
The commutation logic table of the motor shown as below table :
Table 6-1 commutation logic table
HALL Sensors Top Low
SU SV SW UT VT WT UL VL WL
0 0 1 1 0 0 0 0 1
0 1 1 1 0 0 0 1 0
1 1 1 0 0 1 0 1 0
1 1 0 0 0 1 1 0 0
1 0 0 0 1 0 1 0 0
0 0 0 0 1 0 0 0 1
6.2 Main Control Board
Figure 6-1 Main board of the controller

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6.3 Operation method and test data
6.3.1 Test outline
Following steps should be done when run a BLDC motor by using the controller:
1) Connect all cables to the BL motor correctly, including hall signals, phase lines and power supply.
2) Set correct DC +14.4V on DC power supply.
3) Power on the system.
4) Test the related value at 3 speed level with no load.
6.3.2 Test result
Figure 6-2 Hall signal at low speed
Figure 6-3 Hall signal at mid speed