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Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
5-18
5.2.5 Synchronous Serial I/O Configuration
The synchronous serial I/O unit (SSIO) is shown in Figure 5-11. Its single configuration register
bit is in the SIOCFG register (Figure 5-10). The transmit buffer empty and receive buffer full sig-
nals (SSTBE and SSRBF) go to the DMA unit (Figure 5-2), and an interrupt signal (SSIOINT)
goes to the ICU (Figure 5-4). Depending on the settings in the SSIOCON1 register (see Chapter
13), SSIOINT is asserted for one of two conditions: the receive buffer is full or the transmit buffer
is empty. Note that using the SSIO signals precludes the use of four of the SIO1 modem signals.
Figure 5-11. SSIO Unit Configuration
A2518-02
Receive Data
Transmit Data
Transmit Clock
SSIO
Receive Clock
0
1
SSIOTX
(RTS1#)
From SIO1
PINCFG.0
PSCLK
SIOCFG.2
SSIORX
(RI1#)*
To SIO1
*Alternate pin signals are in parentheses.
SERCLK
BCLKIN
STXCLK
(DSR1#)
To SIO1
SRXCLK
(DTR1#)
From SSIO1
PINCFG.1
To ICU
To DMA
To DMA
SSIOINT
SSRBF
SSTBE
0
1
0
1