MC81F4x16
23. SERIAL I/O INTERFACE
SIO INT
3-Bit Counter Clear
CCLR
SIOIR
CLK
SIO INT request
SIOIE
CSEL
SIO INT enable
SEDGE
SIOP
(Edge Select)
(Shift Enable)
SIOM
M
U
X
SCK
fxx/2
(Mode Select)
CLK
SIOPS
8-Bit SIO Shift Buffer
(SIODATA)
SO
8-bit P.S.
1/2
DAT
(LSB/MSB First
Mode Select)
Prescaler Value = 1/(SIOPS +1)
8
SI
Data Bus
Figure 23-1 SIO Block Diagram
Serial I/O interface modules, SIO can interface with various types of external device that require serial
data transfer. The components of SIO function block are:
-
-
-
-
-
-
-
8-bit control register (SIOCR)
Clock selector logic
8-bit data register (SIODAT)
8-bit pre-scaler register (SIOPS)
3-bit clock counter
Serial data I/O pins (SI, SO)
Serial clock pin (SCK)
The SIO module can transmit or receive 8-bit serial data at a frequency determined by its
corresponding control register settings. To ensure flexible data transmission rates, you can select
internal or external clock source.
146
October 19, 2009 Ver.1.35
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