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

R01AN1386EJ0100 Rev. 1.00 Page 3 of 10

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.)

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

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

R01AN1386EJ0100 Rev. 1.00 Page 4 of 10

Jan. 18, 2013

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

R01AN1386EJ0100 Rev. 1.00 Page 5 of 10

Jan. 18, 2013

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

32 MHz: Transfer the value in the

FRA6 register to the FRA1

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

≤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

R01AN1386EJ0100 Rev. 1.00 Page 6 of 10

Jan. 18, 2013

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

High-speed system clock oscillator

1 to 20 MHz

2.7 V ≤VDD ≤5.5 V

1 to 8 MHz

1.8 V ≤V

≤2.7 V

1 to 4 MHz

1.6 V ≤V

≤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

R8C/36M Group

XIN clock oscillation circuit

RL78/G14

High-speed system clock

oscillator

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

≤5.5 V

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator

R01AN1386EJ0100 Rev. 1.00 Page 7 of 10

Jan. 18, 2013

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

High-speed on-chip oscillator

1, 4, 8, 12, 16, 24, 32, 48, 64 MHz

(typ.)

1.6 V ≤V

≤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

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

XCIN clock oscillation circuit

32.768 to 50 kHz

1.8 V ≤V

≤5.5 V

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator

R01AN1386EJ0100 Rev. 1.00 Page 8 of 10

Jan. 18, 2013

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

Subsystem clock oscillator

32 to 35 kHz

1.6 V ≤V

≤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

50 R8C/36MGroup

XCIN clock oscillation circuit

RL78/G14

Subsystem clock oscillator

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

≤5.5 V

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator

R01AN1386EJ0100 Rev. 1.00 Page 9 of 10

Jan. 18, 2013

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

Low-speed on-chip oscillator

15 kHz (typ.)

1.6 V ≤V

≤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

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

XCIN clock oscillation circuit

XT1 oscillator

Subsystem clock oscillator

Low-speed on-chip oscillator

Peripheral function

Watchdog timer

Supply voltage

RL78/G14, R8C/36M Group Migration Guide from R8C to RL78: Clock Generator

R01AN1386EJ0100 Rev. 1.00 Page 10 of 10

Jan. 18, 2013

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/

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