Hitachi SH7709S, Руководство по оборудованию

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566
Bits 6 to 3—Ir Clock Select Bits (ICK3 to ICK0)
Bit 2—Output Pulse Width Select (PSEL): PSEL selects an IrDA output pulse width that is 3/16
of the bit length for 115 kbps or 3/16 of the bit length for the selected baud rate.
The Ir clock select bits should be set properly to fix the output pulse width at 3/16 of the bit length
for 115 kbps by setting the PSEL bit to 1.
Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Description
ICK3 ICK2 ICK1 ICK0 PSEL Pulse width: 3/16 of 115 kbps bit length
ICK3 ICK2 ICK1 ICK0 1
Don’t
care Don’t
care Don’t
care Don’t
care 0 Pulse width: 3/16 of bit length
It is necessary to generate a fixed clock pulse, IRCLK, by dividing the P
φ
clock by 1/2N + 2 (with
the value of N determined by the setting of ICK3–ICK0).
Example:
P
φ
clock: 14.7456 MHz
IRCLK: 921.6 kHz (fixed)
N: Setting of ICK3–ICK0 (0
≤
N
≤
15)
– 1
≥
7 N
≥
P
φ
2XIRCLK
Accordingly, N is 7.
Bits 1 and 0—Clock Select 1 and 0 (CKS1, CKS0): Select the internal baud rate generator clock
source. P
φ
, P
φ
/4, P
φ
/16, or P
φ
/64 can be selected by setting the CKS1 and CKS0 bits.
Refer to section 14.2.9, Bit Rate Register (SCBRR), for the relationship between the clock source,
the bit rate register set value, and the baud rate.
Bit 1: CKS1 Bit 0: CKS0 Description
0 0 P
φ
clock (Initial value)
0 1 P
φ
/4 clock
1 0 P
φ
/16
1 1 P
φ
/64
Note: P
φ
: Peripheral clock