KS57C2308/P2308/C2316/P2316
OSCILLATOR CIRCUITS
6-5
POWER CONTROL REGISTER (PCON)
The power control register (PCON) is a 4-bit register that is used to select the CPU clock frequency and to
control CPU operating and power-down modes. The PCON can be addressed directly by 4-bit write instructions
or indirectly by the instructions IDLE and STOP.
FB3H
PCON.3
PCON.2
PCON.1
PCON.0
PCON
PCON.3 and PCON.2 can be addressed only by the STOP and IDLE instructions, respectively, to engage the
idle and stop power-down modes. Idle and stop modes can be initiated by these instruction despite the current
value of the enable memory bank flag (EMB). PCON bits 1 and 0 can be written only by 4-bit RAM control
instruction. PCON is a write-only register. There are three basic choices:
— Main system clock (fx) or subsystem clock (fxt);
— Divided fx clock frequency of 4, 8, or 64
— Divided fxt clock frequency of 4.
PCON.1 and PCON.0 settings are also connected with the system clock mode control register, SCMOD. If
SCMOD.0 = "0", the main system clock is always selected by the PCON.1 and PCON.0 setting; if SCMOD.0 =
"1" the subsystem clock is selected.
RESET
clears PCON register values (and SCMOD) to logic zero.
Table 6-1. Power Control Register (PCON) Organization
PCON Bit Settings
Resulting CPU Clock Frequency
PCON.1
PCON.0
SCMOD.0 = 0
SCMOD.0 = 1
0
0
fx/64
fxt/4
1
0
fx/8
1
1
fx/4
PCON Bit Settings
Resulting CPU Operating Mode
PCON.3
PCON.2
0
0
Normal CPU operating mode
0
1
IDLE
1
0
STOP mode
Summary of Contents for KS57C2308
Page 30: ...ADDRESS SPACES KS57C2308 P2308 C2316 P2316 2 22 NOTES ...
Page 168: ...SAM47 INSTRUCTION SET KS57C2308 P2308 C2316 P2316 5 94 NOTES ...
Page 170: ......
Page 206: ...POWER DOWN KS57C2308 P2308 C2316 P2316 8 8 NOTES ...
Page 210: ...RESET KS57C2308 P2308 C2316 P2316 9 4 NOTES ...
Page 222: ...I O PORTS KS57C2308 P2308 C2316 P2316 10 12 NOTES ...
Page 272: ...LCD CONTROLLER DRIVER KS57C2308 P2308 C2316 P2316 12 24 NOTES ...
Page 280: ...SERIAL I O INTERFACE KS57C2308 P2308 C2316 P2316 13 8 NOTES ...
Page 294: ...MECHANICAL DATA KS57C2308 P2308 C2316 P2316 15 2 NOTES ...
Page 310: ...KS57P2308 P2316 OTP KS57C2308 P2308 C2316 P2316 16 16 NOTES ...
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