Renesas rl78 User Manual
RL78/G1A
CHAPTER 5 CLOCK GENERATOR
R01UH0305EJ0200 Rev.2.00
157
Jul 04, 2013
5.3.9 High-speed on-chip oscillator trimming register (HIOTRM)
This register is used to adjust the accuracy of the high-speed on-chip oscillator.
With self-measurement of the high-speed on-chip oscillator frequency via a timer using high-accuracy external clock
input (timer array unit), and so on, the accuracy can be adjusted.
The HIOTRM register can be set by an 8-bit memory manipulation instruction.
Caution The frequency will vary if the temperature and V
DD
pin voltage change after accuracy adjustment.
When the temperature and V
DD
voltage change, accuracy adjustment must be executed regularly or
before the frequency accuracy is required.
Figure 5-10. Format of High-Speed On-Chip Oscillator Trimming Register (HIOTRM)
Address: F00A0H After reset: Undefined
Note
R/W
Symbol
7 6 5 4 3 2 1 0
HIOTRM 0
0 HIOTRM5
HIOTRM4
HIOTRM3
HIOTRM2
HIOTRM1
HIOTRM0
HIOTRM5 HIOTRM4 HIOTRM3
HIOTRM2
HIOTRM1
HIOTRM0
High-speed on-chip
oscillator
0 0 0 0 0 0 Minimum speed
0 0 0 0 0 1
0 0 0 0 1 0
0 0 0 0 1 1
0 0 0 1 0 0
•
•
•
•
•
1 1 1 1 1 0
1 1 1 1 1 1 Maximum speed
Note The value after reset is the value adjusted at shipment.
Remarks 1. The HIOTRM register can be used to adjust the high-speed on-chip oscillator clock to an
accuracy within about 0.05%.
2.
For the usage example of the HIOTRM register, see the application note for RL78 MCU
series High-speed On-chip Oscillator (HOCO) Clock Frequency Correction (R01AN0464).