7 I/O PORTS (PPORT)
7-10
Seiko Epson Corporation
S1C31D50/D51 TECHNICAL MANUAL
(Rev. 2.00)
P Port Clock Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
PPORTCLK
15–9 –
0x00
–
R
–
8
DBRUN
0
H0
R/WP
7–4 CLKDIV[3:0]
0x0
H0
R/WP
3–2 KRSTCFG[1:0]
0x0
H0
R/WP
1–0 CLKSRC[1:0]
0x0
H0
R/WP
Bits 15–9 Reserved
Bit 8
DBRUN
This bit sets whether the PPORT operating clock is supplied during debugging or not.
1 (R/WP): Clock supplied during debugging
0 (R/WP): No clock supplied during debugging
Bits 7–4
CLKDIV[3:0]
These bits select the division ratio of the PPORT operating clock (chattering filter clock).
Bits 3–2
KRSTCFG[1:0]
These bits configure the key-entry reset function.
Table 7.6.2 Key-Entry Reset Function Settings
PPORTCLK.KRSTCFG[1:0] bits
key-entry reset
0x3
Reset when P0[3:0] inputs = all low
0x2
Reset when P0[2:0] inputs = all low
0x1
Reset when P0[1:0] inputs = all low
0x0
Disable
Bits 1–0
CLKSRC[1:0]
These bits select the clock source of PPORT (chattering filter).
The PPORT operating clock should be configured by selecting the clock source using the PPORT-
CLK.CLKSRC[1:0] bits and the clock division ratio using the PPORTCLK.CLKDIV[3:0] bits as
shown in Table 7.6.3. These settings determine the input sampling time of the chattering filter.
Table 7.6.3 Clock Source and Division Ratio Settings
PPORTCLK.CLKDIV[3:0]
bits
PPORTCLK.CLKSRC[1:0] bits
0x0
0x1
0x2
0x3
IOSC
OSC1
OSC3
EXOSC
0xf
1/32,768
1/1
0xe
1/16,384
0xd
1/8,192
0xc
1/4,096
0xb
1/2,048
0xa
1/1,024
0x9
1/512
0x8
1/256
0x7
1/128
0x6
1/64
0x5
1/32
0x4
1/16
0x3
1/8
0x2
1/4
0x1
1/2
0x0
1/1
(Note) The oscillation circuits/external input that are not supported in this IC cannot be
selected as the clock source.