upd17240 Renesas Electronics Corporation., upd17240 Datasheet - Page 47

• Manufacturer Part Number: upd17240
• Description: 4-bit Single-chip Microcontrollers For Small General-purpose Infrared Remote Control Transmitters
• Manufacturer: Renesas Electronics Corporation.

4.
4.1
Instruction execution time can be changed in two steps (normal mode and high-speed mode) without changing the
oscillation frequency.
using the POKE instruction.
The µ PD17246 is equipped with a clock oscillator that supplies clocks to the CPU and peripheral hardware.
To change the instruction execution time, change the mode of SYSCK (RF: address 02H) of the register file by
Note, that the mode is actually only changed when the instruction next to the POKE instruction has been executed.
When using the high-speed mode, pay attention to the supply voltage. (Refer to 14. ELECTRICAL SPECIFICATIONS.)
After reset, the normal mode is set.
CLOCK GENERATOR
Instruction Execution Time (CPU Clock) Selection
3
0
0
2
µ PD17240, 17241, 17242, 17243, 17244, 17245, 17246
0
1
SYSCK
0
Values in parentheses apply to operation when the system clock f
Data Sheet U15002EJ1V1DS
SYSCK
Address
RF: 02H
0
1
Normal mode 32/f
High-speed mode 16/f
After reset
0H
Selects instruction execution time
X
R/W
R/W
(8 s)
µ
X
(4 s)
µ
X
= 4 MHz.
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