GMS81C1404 Datasheet, PDF (53/93 Pages) Hynix Semiconductor – 8-BIT SINGLE-CHIP MICROCONTROLLERS

GMS81C1404/GMS81C1408
14. Serial Peripheral Interface
The Serial Peripheral Interface (SPI) module is a serial in-
terface useful for communicating with other peripheral of
microcontroller devices. These peripheral devices may be
serial EEPROMs, shift registers, display drivers, A/D con-
verters, etc.
SPI Mode Control Register
SIOM
POL
SRDY
SM1
SM0
SCK1 SCK0 SIOST SIOSF
ADDRESS : E0H
RESET VALUE : 00000001
POL
SRDY
SM[1:0]
Serial Clock Polarity Selection bit.
0 : Data Transmission at falling edge
(Received data latch at rising edge)
1 : Data Transmission at rising edge
(Received data latch at falling edge)
Serial Ready Enable bit
0 : Disable (RC3)
1 : Enable (SRDYIN / SRDYOUT)
Serial Operation Mode Selection bits
00 : Normal Port (RC4, RC5, RC6)
01 : Transmit Mode (SCK, RC5, SOUT)
10 : Receive Mode (SCK, SIN, RC6)
11 : Transmit & Receive Mode (SCK, SIN, SOUT)
SCK[1:0]
SIOST
SIOSF
Serial Clock Selection bits
00 : fxin ÷ 4
01 : fxin ÷ 16
10 : TMR2OV (Overflow of Timer 2)
11 : External Clock
Serial Transmit Start bit
0 : Disable
1 : Start (After one SCK, becomes “0”)
Serial Transmit Status bit
0 : During Transmission
1 : Finished
SPI Data Register
SIOR
ADDRESS : E1H
RESET VALUE : Undefined
SOUT
SIN
SCK
SRDY
SM0
SM1
MSB
LSB
SIOR
Octal Counter
POL
Polarity
SCK1
SCK0
SM1
SM0
SPIF (Interrupt Request)
00
01
10
11
2
SCK[1:0]
fxin ÷ 4
fxin ÷ 16
TMR2OV
External Clock
SRDY
R
Q
S
SIOST
From Control Circuit
To Control Circuit
Figure 14-1 SPI Registers and Block Diagram
June. 2001 Ver 1.2
51