Intel 87C196CA, Supplement To User’S Manual

Page: 53 / 136

6-1
CHAPTER 6
SYNCHRONOUS SERIAL I/O PORT
The synchronous serial I/O (SSIO) port on the 8XC196Lx has been enhanced, implementing two
new special function registers (SSIO0_CLK and SSIO1_CLK) that allow you to select the oper-
ating mode and configure the phase and polarity of the serial clock signals.
6.1 SSIO 0 CLOCK REGISTER
The SSIO 0 clock (SSIO_CLK) register selects the phase and polarity for the SC0 clock signal.
In standard mode, SC0 is channel 0’s clock signal. In duplex and channel-select modes, SC0 is
the common clock signal for both SSIO channels.
SSIO0_CLK
Address:
Reset State:
1FB5H
00H
The SSIO 0 clock (SSIO0_CLK) register configures the serial clock for channel 0. In standard mode,
the SC0 is channel 0’s clock signal. In duplex and channel-select modes, SC0 is the common clock
signal for both SSIO channels.
7 0
— — — — — — PHAS POLS
Bit
Number
Bit
Mnemonic
Function
7:2 — Reserved; for compatibility with future devices, write zeros to these bits.
1 PHAS Phase and Polarity Select
For normal transfers, these bits determine the idle state of the serial
clock and select the serial clock signal edge on which the SSIO samples
incoming data bits or shifts out outgoing data bits. These bits are ignored
for handshaking transfers. Use SSIO0_ CON to select the type of data
transfer (normal or handshaking) for channel 0.
For transmissions
PHAS POLS
0 0 low idle state; shift on falling edges
0 1 high idle state; shift on rising edges
1 0 low idle state; shift on rising edges
1 1 high idle state; shift on falling edges
For receptions
PHAS POLS
0 0 low idle state; sample on rising edges
0 1 high idle state; sample on falling edges
1 0 low idle state; sample on falling edges
1 1 high idle state; sample on rising edges
0 POLS
Figure 6-1. SSIO 0 Clock (SSIO0_CLK) Register