Renesas RL78G14 Installation and operating instructions

APPLICATION NOTE
R01AN1386EJ0100 Rev. 1.00 Page 1 of 10
Jan. 18, 2013
RL78/G14, R8C/36M Group
Migration Guide from R8C to RL78: Clock Generator
Abstract
This document describes how to migrate from the R8C/36M Group clock generation circuit to the RL78/G14 clock
generator.
Products
RL78/G14, R8C/36M Group
When using this application note with other Renesas MCUs, careful evaluation is recommended after making
modifications to comply with the alternate MCU.
R01AN1386EJ0100
Rev. 1.00
Jan. 18, 2013

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
R01AN1386EJ0100 Rev. 1.00 Page 2 of 10
Jan. 18, 2013
Contents
1. Differences between the R8C/36M Group and RL78/G14................................................................. 3
1.1 XIN Clock Oscillation Circuit........................................................................................................ 5
1.2 High-speed On-chip Oscillator..................................................................................................... 6
1.3 XCIN Clock Oscillation Circuit...................................................................................................... 7
1.4 Low-speed On-chip Oscillator...................................................................................................... 8
2. Terms.................................................................................................................................................. 9
3. Reference Documents...................................................................................................................... 10

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
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Jan. 18, 2013
1. Differences between the R8C/36M Group and RL78/G14
Table 1.1 and Table 1.2 list the specification overview of the R8C/36M Group clock generation circuit and RL78/G14
clock generator.
Table 1.3 lists the differences between the R8C/36M Group clock generation circuit and RL78/G14 clock generator.
Table 1.1 Overview of the Clock Generation Circuit Specifications for the R8C/36M Group
Item
XIN Clock
Oscillation
Circuit
XCIN Clock
Oscillation
Circuit
On-chip Oscillator
Low-speed
On-chip
Oscillator for
Watchdog
Timer
High-speed
On-chip
Oscillator
Low-speed
On-chip
Oscillator
Applications
•CPU clock source
•Peripheral function clock
source
•CPU clock source
•Peripheral function clock
source
•CPU and peripheral function
clock source when XIN clock
oscillation is stopped
•Watchdog
timer clock
source
Clock frequency
0 to 20 MHz
32.768 kHz
40 MHz (typ.)
(1)
125 kHz (typ.)
125 kHz (typ.)
Applicable
oscillator
•Ceramic
resonator
•Crystal
oscillator
•Crystal
oscillator
‒
‒
‒
Oscillator connect
pins
XIN, XOUT
XCIN, XCOUT
‒
‒
‒
Oscillation stop,
restart function
Applicable
Oscillation status
after reset
Stop
Stop
Stop
Oscillate
Stop, oscillate
Other
Externally-
generated
clock can be
input
•Externally-
generated
clock can be
input
•On-chip
feedback
resistor Rf
(connected or
not connected
selectable)
‒
‒
‒
Note 1. The clock frequency is automatically set to a maximum of 20 MHz (typ.) by a divider when using
the high-speed oscillator as a CPU clock source.

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
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Table 1.2 Overview of the Clock Generator Specifications for the RL78/G14
Item
Main System Clock
Subsystem Clock
Oscillator
Low-speed
On-chip
Oscillator
High-speed
System Clock
Oscillator
High-speed On-chip
Oscillator
Applications
•CPU clock
source
•Peripheral
function clock
source
•CPU clock source
•Peripheral
function clock
source
•CPU clock source
•Peripheral function
clock source
•Watchdog
timer
•Real-time
clock
•12-bit
interval timer
•
Timer RJ
Clock frequency
1 to 20 MHz
64 MHz (typ.) (1)
32.678 kHz
15 kHz (typ.)
Applicable
oscillator
•Ceramic
oscillator
•Crystal
resonator
‒
•Crystal resonator
‒
Oscillator connect
pins
X1, X2
‒
XT1, XT2
‒
Oscillation stop
and restart
function
Applicable
Oscillation status
after reset
Stop
Oscillate
Stop
Oscillate, stop
(2)
Other
Externally-
generated clock
can be input
‒
Externally-generated
clock can be input
‒
Notes 1. When the oscillating frequency is specified as 48 MHz or 64 MHz, the selected clock divided-by-2
is supplied to the CPU clock.
2. This status can be set by the WDTON bit in the user option byte (000C0H).

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
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Table 1.3 Differences in the Clock Generator
Item
R8C/36M Group
RL78/G14
High-speed on-chip oscillator
accuracy
±1.5% (1)
±1% (2)
How to adjust the high-speed on-
chip oscillator frequency
40 MHz: FRA1 = value after reset,
FRA3 = value after reset
36.864 MHz: Transfer the value in
the FRA4 register to the FRA1
register and the value in the FRA5
register to FRA3 register
32 MHz: Transfer the value in the
FRA6 register to the FRA1
register and the value in the FRA7
register to the FRA3 register
The frequency of the high-speed
on-chip oscillator can be selected
from 64, 48, 32, 24, 16, 12, 8, 4
and 1 MHz by using FRQSEL0 to
FRQSEL4 of the option byte
(000C2H).
High-speed on-chip oscillator
stabilization time
100 µs (typ.)
450 µs (max.)
Included in the reset processing
time:
•Reset processing time when
LVD is off: 417 µs (typ.),
554 µs (max.)
•Reset processing time when
LVD is on: 690 µs (typ.),
867 µs (max.)
Low-speed on-chip oscillator
accuracy
−52% to +100%
±15%
CPU clock divider
Available
Available only in the high-speed
on-chip oscillator
CPU clock after reset release
Low-speed on-chip oscillator
High-speed on-chip oscillator
Subsystem clock oscillation mode
select function
Not applicable
Applicable
Notes 1. Measuring conditions of VCC: 1.8 to 5.5 V, −20°C ≤T ≤85°C
2. Measuring conditions of VDD: 1.8 to 5.5 V, −20°C to 85°C
1.1 XIN Clock Oscillation Circuit
Clocks generated by the R8C/36M Group XIN clock oscillation circuit can be used as the clock source for the CPU
clock or the peripheral function clock. To use the XIN clock oscillation circuit, connect a crystal oscillator or ceramic
resonator to pins XIN and XOUT. Also, an externally-generated clock can be input to the XOUT pin. Table 1.4 lists the
relationship between the XIN clock operating frequency and the supply voltage (VCC).
Table 1.4 Operating Frequency and Supply Voltage for the R8C/36M Group
Item
Operating Frequency
VCC
XIN clock oscillation circuit
0 to 20 MHz
2.7 V ≤V
CC
≤5.5 V
0 to 5 MHz
1.8 V ≤VCC ≤2.7 V

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
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Clocks generated by the RL78/G14 high-speed system clock oscillator can be used as the clock source for the CPU
clock or the peripheral function clock. To use the high-speed system clock oscillator, connect a crystal resonator or
ceramic oscillator to pins X1 and X2. An externally-generated clock can be input to the EXCLK pin. Table 1.5 lists the
relationship between the high-speed system clock oscillator operating frequency and the supply voltage (VDD).
Table 1.5 Operating Frequency and Supply Voltage for the RL78/G14
Item
Operating Frequency
V
DD
High-speed system clock oscillator
1 to 20 MHz
2.7 V ≤VDD ≤5.5 V
1 to 8 MHz
1.8 V ≤V
DD
≤2.7 V
1 to 4 MHz
1.6 V ≤V
DD
≤1.8 V
A comparison of the operating frequencies between the R8C/36M Group's XIN clock oscillation circuit and the
RL78/G14 high-speed system clock oscillator is shown in Figure 1.1.
Supply voltage (V)
Frequency
(MHz)
1.6 1.8 2.7 5.5
4
8
20
1
R8C/36M Group
XIN clock oscillation circuit
RL78/G14
High-speed system clock
oscillator
5
Figure 1.1 Comparison of Operating Frequencies between XIN Clock Oscillation Circuits
1.2 High-speed On-chip Oscillator
Clocks generated by the R8C/36M Group high-speed on-chip oscillator can be used as the clock source for the CPU
clock, the peripheral function clock, fOCO, fOCO-F, fOCO40M, or fOCO128. The oscillating frequency can be
specified as 40, 36.864, or 32 MHz by adjusting values in registers FRA1 and FRA3. Table 1.6 lists the relationship
between the high-speed on-chip oscillator operating frequency and the supply voltage (VCC).
Table 1.6 R8C/36M Group MCU Operating Frequency and Supply Voltage
Item
Operating Frequency
VCC
High-speed on-chip oscillator
•40 MHz (typ.)
•36.684 MHz (typ.)
•
32 MHz (typ.)
1.8 V ≤V
CC
≤5.5 V

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Clocks generated by the RL78/G14 high-speed on-chip oscillator can be used as the clock source for the CPU clock or
the peripheral function clock. The fHOCO oscillating frequency can be specified as 64, 48, 32, 24, 16, 12, 8, 4, or 1 MHz
by setting the user option byte. When fHOCO is specified as 64 MHz or 48 MHz, fIH is automatically set to 32 MHz or
24 MHz, respectively. When fHOCO is specified as 32 MHz or below, fIH is not divided and is set to the same frequency
as fHOCO. The high-speed on-chip oscillator clock is automatically set to the CPU clock after reset is released. Table 1.7
lists the relationship between the high-speed on-chip oscillator operating frequency and supply voltage (VDD).
Table 1.7 Operating Frequency and Supply Voltage for the RL78/G14
Item
Operating Frequency
V
DD
High-speed on-chip oscillator
1, 4, 8, 12, 16, 24, 32, 48, 64 MHz
(typ.)
1.6 V ≤V
DD
≤5.5 V
A comparison of the operating frequencies between the R8C/36M Group's high-speed on-chip oscillator and the
RL78/G14 high-speed on-chip oscillator is shown in Figure 1.2.
Supply voltage (V)
Frequency
(MHz)
1.6 1.8 2.4 2.7 5.5
4
8
16
32
1
40
R8C/36M Group
High-speed on-chip oscillator
RL78/G14
High-speed on-chip oscillator
Figure 1.2 Comparison of Operating Frequencies between High-speed On-chip Oscillators
1.3 XCIN Clock Oscillation Circuit
Clocks generated by the R8C/36M Group XCIN clock oscillation circuit can be used as the clock source for the CPU
clock or the peripheral function clock. To use the XCIN clock oscillation circuit, connect a crystal oscillator to pins
XCIN and XCOUT. An externally-generated clock can be input to the XCIN pin. Table 1.8 lists the relationship
between the XCIN clock oscillation circuit operating frequency and supply voltage (VCC).
Table 1.8 Operating Frequency and Supply Voltage for the R8C/36M Group
Item
Operating Frequency
V
CC
XCIN clock oscillation circuit
32.768 to 50 kHz
1.8 V ≤V
CC
≤5.5 V

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Clocks generated by the RL78/G14 XT1 oscillator can be used as the clock source for the CPU clock or the peripheral
function clock. The power consumption and oscillation margin for the XT1 oscillator can be adjusted by selecting the
oscillation mode. To use the XT1 oscillator, connect a crystal resonator to pins XT1 and XT2. An externally-generated
clock can be input to the EXCLKS pin. Table 1.9 lists the relationship between the subsystem clock oscillator operating
frequency and the supply voltage (VDD).
Table 1.9 Operating Frequency and Supply Voltage for the RL78/G14
Item
Operating Frequency
V
DD
Subsystem clock oscillator
32 to 35 kHz
1.6 V ≤V
DD
≤5.5 V
A comparison of the operating frequencies between the R8C/36M Group's XCIN clock oscillation circuit and the
RL78/G14 subsystem clock oscillator is shown in Figure 1.3.
Supply voltage
(V)
Frequency
(kHz)
1.6 1.8 5.5
32
50 R8C/36MGroup
XCIN clock oscillation circuit
RL78/G14
Subsystem clock oscillator
35
32.768
Figure 1.3 Comparison of Operating Frequencies between XCIN Clock Oscillation Circuits
1.4 Low-speed On-chip Oscillator
Clocks generated by the R8C/36M Group low-speed on-chip oscillator can be used as the clock source for the CPU
clock, the peripheral function clock, fOCO, fOCO-S, or fOCO128. After a reset is released, clocks generated by the
low-speed on-chip oscillator divided-by-1 (no division) are selected as the CPU clock. Table 1.10 lists the relationship
between the low-speed on-chip oscillator operating frequency and the supply voltage (VCC).
Table 1.10 Operating Frequency and Supply Voltage for the R8C/36M Group
Item
Operating Frequency
VCC
Low-speed on-chip oscillator
125 kHz (typ.)
1.8 V ≤V
CC
≤5.5 V

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Clocks generated by the RL78/G14 low-speed on-chip oscillator can be used as the clock source for the watchdog timer,
real-time clock, 12-bit interval timer, or timer RJ. It cannot be used as the clock source for the CPU clock. After a reset
is released, the RL78/G14 low-speed on-chip oscillator stops when bit 4 (WDTON) in the option byte (000C0H) is 0, or
oscillates when bit 4 in the option byte is 1. Table 1.11 lists the relationship between the low-speed on-chip oscillator
operating frequency and the supply voltage (VDD).
Table 1.11 Operating Frequency and Supply Voltage for the RL78/G14
Item
Operating Frequency
V
DD
Low-speed on-chip oscillator
15 kHz (typ.)
1.6 V ≤V
DD
≤5.5 V
A comparison of the operating frequencies between the R8C/36M Group's low-speed on-chip oscillator and the
RL78/G14 low-speed on-chip oscillator is shown in Figure 1.4.
Supply voltage
(V)
Frequency
(kHz)
1.6 1.8 5.5
R8C/36M Group
Low-speed on-chip oscillator
RL78/G14
Low-speed on-chip oscillator
125
15
Figure 1.4 Comparison of Operating Frequencies between Low-speed On-chip Oscillators
2. Terms
Table 2.1 lists the comparison of terms between the R8C/36M Group and RL78/G14.
Table 2.1 Comparison of Terms between the R8C/36M Group and RL78/G14
Item
R8C/36M Group
RL78/G14
Oscillator
XIN clock oscillation circuit
High-speed system clock oscillator
High-speed on-chip oscillator
High-speed on-chip oscillator
XCIN clock oscillation circuit
XT1 oscillator
Subsystem clock oscillator
Low-speed on-chip oscillator
Low-speed on-chip oscillator
Peripheral function
Watchdog timer
Watchdog timer
Supply voltage
V
CC
V
DD

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator
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3. Reference Documents
User’s Manual: Hardware
RL78/G14 User’s Manual: Hardware Rev.1.00
R8C/36M Group User’s Manual: Hardware Rev.1.01
The latest versions can be downloaded from the Renesas Electronics website.
Technical Update/Technical News
The latest information can be downloaded from the Renesas Electronics website.
Website and Support
Renesas Electronics website
http://www.renesas.com
Inquiries
http://www.renesas.com/contact/