C515C_9711 Datasheet, PDF (73/268 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C515C
6.1.1.2.4 SSC Port Pins of Port 4
The port pins of the SSC interface are located as alternate functions at four lines of port 4 :
– P4.1/SCLK : when used as SSC clock output, pin becomes a true push-pull output
– P4.2/SRI : when used as SSC receiver input, pin becomes an input without pullups.
– P4.3/STO : when used as SSC transmitter output, pin becomes a true push-pull output with
tristate capability
– P4.4/SLS : when used as SSC slave select input, pin directly controls the tristate condition
of P4.3
The modified port 4 structure for the two SSC outputs SCLK and STO is illustrated in figure 6-7.
This figure can be compared with figure 6-4.
Delay = 1 State
Enable Push-pull
&
=1
V_CC
1
p1
p2
p3
1
1
Port
Pin
Q
&
n1
Tristate
1
Input Data (Read Pin)
V_SS
=1
=1
MCS02432
Figure 6-7
Driver Circuit of Port 4 Pins P4.1and P4.3 (when used for SLCK and STO)
Pin Control for P4.1/SCLK
When the SSC is disabled, both control lines “Enable Push-pull“ and “Tristate“ will be inactive, the
pin behaves like a standard IO pin. In master mode with SSC enabled, “Enable Push-pull“ will be
active and “Tristate“ will be inactive. In slave mode with SSC enabled, “Enable Push-pull“ will be
inactive and “Tristate“ will be active.
Pin Control for P4.3/STO
When the SSC is disabled, both control lines “Enable Push-pull“ and “Tristate“ will be inactive. In
master mode with SSC enabled, “Enable Push-pull“ will be active and “Tristate“ will be inactive. In
slave mode with SSC enabled, “Enable Push-pull“ will be active. If the transmitter is enabled (SLS
and TEN active), “Tristate“ will be inactive. If the transmitter is disabled (either SLS or TEN inactive),
“Tristate“ will be active.
Semiconductor Group
6-10
1997-11-01