7 PRESCALER (PSC)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
7-1
Prescaler (PSC)
7
PSC Module Overview
7.1
The S1C33L26 incorporates a prescaler (PSC) module to generate clocks for timer and serial interface operations.
The PSC module consists of two frequency dividers (PSC Ch.0 and PSC Ch.1) that generate 15 different frequen-
cies by dividing the PCLK1 and PCLK2 clock supplied from the clock management unit (CMU) into 1/1 to 1/16K.
The peripheral modules to which the clock is supplied include clock-select registers enabling selection of one as a
count or operation clock.
1/1
PCLK1
Debug
status signal
PSC Ch.0
1/2
1/4
1/8
1/16 1/32 1/64 1/128
1/256 1/512 1/1K 1/2K 1/4K 1/8K 1/16K
USI
A/D converter trigger
16-bit PWM timer (T16A5) Ch.0, 1
16-bit audio PWM timer (T16P)
8-bit programmable timer (T8) Ch.0
8-bit programmable timer (T8) Ch.2
8-bit programmable timer (T8) Ch.4
8-bit programmable timer (T8) Ch.6
1/1
PCLK2
Debug
status signal
PSC Ch.1
1/2
1/4
1/8
1/16 1/32 1/64 1/128
1/256 1/512 1/1K 1/2K 1/4K 1/8K 1/16K
USIL
GPIO
Remote controller (REMC)
A/D converter (ADC10)
8-bit programmable timer (T8) Ch.1
8-bit programmable timer (T8) Ch.3
8-bit programmable timer (T8) Ch.5
8-bit programmable timer (T8) Ch.7
1.1 Prescaler Configuration
Figure 7.
PSC Ch.0 and PSC Ch.1 are controlled by PRUN/PSC_CTL register. To operate the prescalers, write 1 to PRUN.
Writing 0 to PRUN stops the prescalers. Stopping the prescalers while the timer and interface modules are halted
enables the current consumption to be reduced. The prescalers are stopped at initial reset.
Note: PCLK1 and PCLK2 must be supplied from the CMU to use the PSC Ch.0 and PSC Ch.1, respec-
tively.
The PSC module features another control bit, PRUND/PSC_CTL register, which specifies prescaler operations in
debug mode. Setting PRUND to 1 operates the prescalers in debug mode. Setting it to 0 stops the prescalers when
the C33 PE Core enters debug mode. Set PRUND to 1 when operating the timer and interface modules during de-
bugging.
Control Register Details
7.2
2.1 PSC Register
Table 7.
Address
Register name
Function
0x300e00
PSC_CTL
PSC Control Register
Control prescaler
The prescaler register is an 8-bit register.
Note: When data is written to the register, the “Reserved” bits must always be written as 0 and not 1.
PSC Control Register (PSC_CTL)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
PSC Control
Register
(PSC_CTL)
0x300e00
(8 bits)
D7–2 –
reserved
–
–
–
0 when being read.
D1
PRUND
Prescaler run/stop in debug mode 1 Run
0 Stop
0
R/W
D0
PRUN
Prescaler run/stop control
1 Run
0 Stop
0
R/W
D[7:2]
Reserved