GMS84512 Datasheet, PDF (55/123 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCOMPUTER

GMS 84512 / 84524
3.5.3 Data Transmission/Receving Timing
Serial transmission is started by setting SIOST(bit1 SIOM) to :”1”. After one cycle of SCK,
SIOST is cleared automatically to “0”. serial output data from 8-bit shift register is output at
folloing edge of Sclk. and input data is latched at rising edge of Sclek. When transmission Clock
is counted 8times, serial I/O counter is cleared as “0”. Transmission clock is halted in “H” state
and serial I/O interrupt (IFSIO) occursg.
Input Clock
Sclk
SIOST
Sout
Sin
Output
D0
D1
D2
D3
D4
D5
D6
D7
Latch
D0
D1
D2
D3
D4
D5
D6
D7
IFSIO
FIG. 3.5.1 Timing Diagram of Serial I/O
3.5.4 Data Transmission/Receiving Method
- Select transmission/receiving mode
<Notice>
When external clock is used, the frequency should be less than 1MH and recommanded
duty is 50%.
- When sending Data to be send is written at SIOR.
- Set SIOST to “1” to start serial transmission.
<Notice >
If both transmission mode selection and starting transmission is performed
simultaneouslyit makes error.
- IFSIO is generated at completion and SIOSF is set to “1”. In SIO interrupt service routine
correct transmission should be tested.
- When receiving, receiving data is acquired by reading the SIOR.
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