SN8P26L38
8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 115
Version 1.5
11
SERIAL INPUT/OUTPUT
TRANSCEIVER (SIO)
11.1
OVERVIEW
The SIO (serial input/output) transceiver is a serial communicate interface for data exchanging from one MCU to one
MCU or other hardware peripherals. It is a simple 8-bit interface without a major definition of protocol, packet or control
bits. The SIO transceiver includes three pins, clock (SCK), data input (SI) and data output (SO) to send data between
master and slaver terminals. The SIO interface builds in 8-mode which are the clock idle status, the clock phases and
data fist bit direction. The 8-bit mode supports most of SIO/SPI communicate format.
The SIO features include the following:
Full-duplex, 3-wire synchronous data transfer.
Master (SCK is clock output) or Slave (SCK is clock input) operation.
MSB/LSB first data transfer.
The start phase of data sampling location selection is 1
st
-phase or 2
nd
-phase controlled register.
SCK, SI, SO are programmable open-drain output pin for multiple salve devices application.
Two programmable bit rates (Only in master mode).
End-of-Transfer interrupt.
11.2
SIO OPERATION
The SIOM register can control SIO operating function, such as: transmit/receive, clock rate, data transfer direction, SIO
clock idle status and clock control phase and starting this circuit. This SIO circuit will transmit or receive 8-bit data
automatically by setting SENB and START bits in SIOM register. The SIO data buffer is double buffer design. When
the SIO operating, the SIOB register stores transfer data and one internal buffer stores receive data. When SIO
operation is successfully, the internal buffer reloads into SIOB register automatically. The SIO 8-bit counter and SIOR
register are designed
to generate SIO’s clock source with auto-reload function. The 3-bit I/O counter can monitor the
operation of SIO and announce an interrupt request after transmitting/ receiving 8-bit data. After transferring 8-bit data,
this circuit will be disabled automatically and re-transfer data by programming SIOM register. CPOL bit is designed to
control SIO clock idle status. CPHA bit is designed to control the clock edge direction of data receive. CPOL and CPHA
bits decide the SIO format. The SIO data transfer direction is controlled by MLSB bit to decide MSB first or LSB first.
÷
1
÷
8
÷
16
÷
32
Fcpu
CPUM1,0
SENB
SCK
SENB
SCLKMD
SIO 8-bit Counter
CPUM1,0
SIOR Register
Auto-Reload
CPOL
SIO 3-bit I/O Counter
SIO Time Out
SIOB 8-bit Buffer
8-bit Receive Buffer
MLSB
SO
SENB
CPUM1,0
SI
SENB
CPUM1,0
MLSB
CPHA
Srate1,0
START
SIO Interface Circuit Diagram