Renesas R8C/11 Series Installation and operating instructions

REJ05B0471-0100Z/Rev.1.00 July 2004 Page 1 of 21
A
PPLICATION NOTE
R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator
Using a Commercial Frequency
1. Abstract
This application note describes a program that adjusts the oscillation frequency of the high-speed on-chip
oscillator using a commercial frequency (50/60 Hz).
2. Introduction
The explanation of this issue is applied to the following condition:
Microcomputer : R8C/11, R8C/13 Group
RAM size, ROM size :1 Kbytes, 16 Kbytes
This program can also be used when operating other microcomputers within the R8C/Tiny, provided they
have the same SFR (Special Function Registers) as the R8C/11 microcomputers. However, some functions
may have been modified.
Refer to the Hardware Manual for details. Use functions covered in thisApplication Note only after careful
evaluation.
3. Contents
3.1 Outline of the High-speed On-chip Oscillator
The R8C/11 group of microcomputers incorporate approximately an 8 MHz high-speed on-chip oscillator. The
operating oscillation frequency of the on-chip oscillator tends to fluctuate due to external factors such as the
operating temperature and power supply voltage. The oscillation frequency can be adjusted by setting up the
HR1 register appropriately.
The relationship between the set value of the HR1 register and the oscillation period of the high-speed
on-chip oscillator is shown below. However, because the amount of delay in each bit is not even, be sure to
change each bit to adjust. Also make sure bit 7 is set to “0”.
b5 b4 b3 b2 b1 b0
Oscillation period of the high-speed on-chip oscillator=td(HRoffset)+(b6+ 2 + 4 + 8 + 16 + 32 + 64 ) ×td(HR)
This application note explains how to adjust the oscillation frequency of the high-speed on-chip oscillator
using a commercial frequency (50/60 Hz).

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R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
3.2 Outline of the Program
The following shows how to adjust the oscillation frequency of the high-speed on-chip oscillator using a
commercial frequency.
Measure the commercial frequency with timer C that uses the high-speed on-chip oscillator as its count
source. Adjust the high-speed on-chip oscillator to 8 MHz by adjusting the HR1 register in such a way that
the measured value and the logical value match.
The logical value can be obtained by the equation given below.
Expected frequency of the high-speed on-chip oscillator
Logical measurement value of timer C = Commercial frequency ×Divide-by-N value of the high-speed on-chip oscillator
Figure 1. Measuring the Commercial Frequency
The adjustment rate of the HR1 register (difference in the oscillation period when the HR1 register is set to
00h and when it is set to 01h) is 1 ns. Table 1 shows the relationship between the set value of the HR1
register and the measured value of timer C in cases where when the HR1 register is set to “n” the oscillation
frequency can be adjusted to 8 MHz.
Table 1. HR1 Set Value and Timer C Measured Value
Oscillation of the high-speed
on-chip oscillator Timer C measured value (when measuring 60 Hz)
HR1 set
value Period Frequency Not divided Divided by 8
n-2 123ns 8.13MHz 135501 16938
n-1 124ns 8.06MHz 134409 16801
n 125ns 8.00MHz 133333 16667
n+1 126ns 7.94MHz 132275 16534
n+2 127ns 7.87MHz 131234 16404
In this application note, timer C is used as divided-by-8, and the measured value is divided by 100 before
being compared with the logical value (166). When the measured value and the logical value match, the
oscillation frequency is in the range of 7.97 MHz (timer C measured value = 16600) to 8.02 MHz (timer C
measured value = 16699).
“L”
50Hz or 60Hz
Measured by timer C
Logical measurement value when adjusting the high-speed on-chip oscillator to 8 MHz
Logical valueCommercial
frequency Not divided Divided by 8
50Hz 160000 20000
60Hz 133333 16667
Commercial
frequency
(after converted to
square wave)
“H”

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R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
Adjust the high-speed on-chip oscillator during initial operating time and save the set value in the flash ROM.
Make sure the address to which it is saved does not match that of a block where the program is located.A
sample program memory map is shown in Figure 2.
From the next time on (after the HR1 adjustment value is saved), read the initial value of the HR1 register
from the data flash and set it in the HR1 register. Thereafter, fine-adjust the oscillation frequency each time a
rising edge of the commercial frequency is detected.
Figure 2. Sample Program Memory Map
3.3 Pins Used
Table 2. List of Pins Used and Their Functions
Pin name I/O Fuction
P33/INT
______3/TCIN Input Commercial frequency (square wave) input
Figure 3. Commercial Frequency Input
R8C/11
P33/INT
______3/TCIN
Commercial frequency converter circuit
(sine wave -> square wave)
Note: Power supply voltage is Vcc.
0000h
0400h
041Fh
0420h
0620h
C000h
D000h
D7DBh
E000h
FEDBh
FEDCh
FFDCh
FFFFh
Data area
Stack Area
Program area (Note 1)
HR1 adjustment value (Note 1)
Relocatable vector
Fixed vector
Block 1
Block 0
Note 1: In this application note, the HR1 adjustment value is written using EW1 mode. For this reason,
consideration is taken to ensure that the block where the rewrite program is located and the block into
which the HR1 adjustment value is written will not match.
Commercial powe
r
supply

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Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4. Function Table and Flow Chart
4.1 Function Table
Declaring void main(void)
Outline Main
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Initializes the SFR and performs LOOP processing
Declaring void sfr_init(void)
Outline SFR initialize
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Initializes the SFR
Declaring void first_hz_adjut(void)
Outline Initial frequency adjust
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Adjusts the high-speed on-chip oscillator during initial startup time
Declaring void write_ringadjust_data(unsigned char data)
Outline Frequency adjustment value write
Argument Type MeaningArgument unsigned char data Adjustment value
Return Value Type Value MeaningReturn Value None
Function Description Writes the HR1 register adjustment value to the flash ROM
Declaring void flash_open_ew1_mode(void)
Outline EW1 mode enter
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Enables CPU rewrite mode (EW1 mode)

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R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
Declaring void flash_close_ew1_mode(void)
Outline EW1 mode exit
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Disables CPU rewrite mode (EW1 mode)
Declaring int flash_byte_write(unsigned char *address , unsigned char data)
Outline Flash write
Argument Type Meaning
unsigned char *address Write address
Argument
unsigned char data Write data
Return Value Type Value MeaningReturn Value int chk_flash_status() Flash write status
Function Description Writes 1-byte data (data) to the write address (*address)
Declaring int chk_flash_status(void)
Outline Full status check
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value int chk_flash_status() Flash rewrite status
Function Description Performs full status check and returns the flash rewrite status (terminated
normally, command sequence error, erase error, or programming error).
Declaring void int3_hz_in(void)
Outline High-speed on-chip oscillator adjust (INT3 interrupt)
Argument Type MeaningArgument None
Return Value Type Value MeaningReturn Value None
Function Description Executes interrupt processing upon detecting a falling edge of the input signal to
the INT
______3/TCIN pin. The high-speed on-chip oscillator is adjusted based on the
measured value of timer C.

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R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4.2 Flow Chart
4.2.1 Main Function
main()
sfr_init()
SFR initialize
Initial adjustment finished ?
Yes
No
Set the ports and set the initial value of the HR1
register.
If the adjustment value is saved in the flash ROM (hr1_flash_data !
= 0xFF), it means that the initial adjustment has been completed.
Set clock source for CPU clock
and peripheral function clock to
high-speed on-chip oscillator
first_hz_adjust()
Initial frequency adjust
End
Reset the microcomputer in software after the
initial frequency adjustment has finished.
Set initial adjustment value in HR1
Set tcc0
Count source = f8
Select INT
______3 rising edge
Select INT
______3 interrupt
Set tcc1
No filter
Select capture
Timer C starts
Enable INT
______3 interrupt (level 7)
I flag = 1 (interrupt enabled)

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Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4.2.2 SFR Initialize Function
sfr_init()
Initialize port P3
return
Initialize HR1 register

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R8C/11, R8C/13 Group
Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4.2.3 Initial Frequency Adjust Function
Yes
first_hz_adjut()
Set tcc0
Count source = f8
Select INT
______3 rising edge
Select INT
______3 interrupt
Set tcc1
No filter
Select capture
Yes
No
Wait until the first high-going transition of the commercial
frequency input signal occurs.
Clear INT
______3 interrupt request
Clear INT
______3 interrupt request
No
in_timerc0 = tm0 Save the timer value synchronously with the rising edge of the commercial
frequency input signal.
Clear INT
______3 interrupt request
in_timerc1 = tm0 Save the timer value synchronously with the rising edge of the commercial
frequency input signal.
dat=in_timerc1-in_timerc0 Find the difference with the timer value that was previously saved on the rising edge
of the commercial frequency input signal to measure the period of the commercial
frequency.
in_timerc0 = in_timerc1in_timerc0 = in_timerc1
dat = dat / 100
dat
dat=166
(matches with
logical value)
IR_INT3=0?
IR_INT3=0?
f_upflag = 1
f_downflag = 1
dat<166
(high-speed on-chip oscillator slower
than 8 MHz)
dat>166
(high-speed on-chip oscillator
faster than 8 MHz)
f_upflag=1? f_downflag=1?
Frequency adjustment value write
write_ringadjust_data(hr1)
HR1 != 0x00? HR1 < 0x7f?
HR1 = HR1 + 1HR1 = HR1 - 1
Frequency adjustment
value write
write_ringadjust_data(hr1)
Does not match with logical value when
f_downflag and f_upflag = 1. The value
at that time is approximated to 8 MHz.
Yes
No
Yes
Yes
Yes
No
No
No
return
return

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Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4.2.4 Frequency Adjustment Value Write Function
4.2.5 EW1 Mode Enter Function
write_ringadjust_data(unsigned char data)
return
[Argument]
data: HR1 adjustment value
Enter the CPU rewrite mode 1 (EW1 mode).
Write the HR1 adjustment value to the flash ROM.
For the address to which to write, specify a block where the program is not
located.
Set the PM03 bit in the PM0 register to “1” (software reset).
Software reset
flash_open_ew1_mode()
EW1 mode enter
flash_byte_write(HR1_FLASH_ROM,data)
Flash write
Exit the CPU rewrite mode 1 (EW1 mode).
flash_close_ew1_mode()
EW1 mode exit
flash_open_ew1_mode()
return
Divide main clock by 8 Before entering the CPU rewrite mode, reduce the CPU clock frequency to 5
MHz or less.
fmr01 = 0
fmr01 = 1
fmr02 = 0
To set the fmr01 bit to “1” (CPU rewrite mode enabled), write “0” and then “1”
in succession.
fmr02 = 1
To set the fmr02 bit to “1” (block 0, 1 rewrite enabled), write “0” and then “1”
in succession.
fmr11 = 0
fmr11 = 1
To set the fmr11 bit to “1” (EW1 mode), write “0” and then “1” in succession.

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Adjusting the Frequency of the High-speed On-chip Oscillator Using a Commercial Frequency
4.2.6 EW1 Mode Exit Function
4.2.7 Flash Write Function
flash_close_ew1_mode()
return
fmr01 = 0 If the fmr01 bit is set to “0” (CPU rewrite mode disabled), the fmr11 bit is also
set to “0” (EW0 mode).
flash_byte_write(unsigned char *address, unsigned char data) [Argument]
*address: Address to which the HR1 adjustment value is written
data: Write data (HR1 adjustment value)
No
Yes
i = 0
flash_address = address
*flash_address = 0x50
A
s a result of full status check, if an error occur
r
ed, issue a
status clear command.
i < 4?
*flash_address = 0x40
*flash_address = data
Issue a program command.
Write 0x40 in the first bus cycle and data in
the second bus cycle.
No error?
fmr00 = 0? Wait until the flash write operation finishes.
chk_flash_status()
Full status check
i = i + 1
return result
Yes
No
Yes
No