User Manual
662
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
High-Speed Synchronous Serial Interface SSC1/SSC2
for master operation generates and outputs the shift clock on line MS_CLK. Since all slaves receive this clock,
their pin SCLK must be switched to input mode. The output of the master’s shift register is connected to the
external transmit line, which in turn is connected to the slaves’ shift register input. The output of the slaves’
shift register is connected to the external receive line in order to enable the master to receive the data shifted
out of the slave. The external connections are hard-wired, the function and direction of these pins is
determined by the master or slave operation of the individual device.
Note:
The shift direction shown in the figure applies for MSB-first operation as well as for LSB-first
operation.
When initializing the devices in this configuration, one device must be selected for master operation while all
other devices must be programmed for slave operation. Initialization includes the operating mode of the
device’s SSC and also the function of the respective port lines.
Figure 179 SSC Full-Duplex Configuration
The data output pins MRST of all slave devices are connected together onto the one receive line in the
configuration shown in
. During a transfer, each slave shifts out data from its shift register. There
are two ways to avoid collisions on the receive line due to different slave data:
• Only one slave drives the line, i.e. enables the driver of its MRST pin. All the other slaves must have their
MRST pins programmed as input so only one slave can put its data onto the master's receive line. Only
receiving data from the master is possible. The master selects the slave device from which it expects data
either by separate select lines, or by sending a special command to this slave. The selected slave then
switches its MRST line to output until it gets a de-selection signal or command.
• The slaves use open drain output on MRST. This forms a wired-AND connection. The receive line needs an
external pull-up in this case. Corruption of the data on the receive line sent by the selected slave is avoided
when all slaves not selected for transmission to the master only send ones (1s). Because this high level is
Master
Device #1
Shift Register
Clock
MTSR
MRST
CLK
CLK
MRST
MTSR
Transmit
Receive
Clock
Clock
Shift Register
Device #2
Slave
Slave
Device #3
MRST
CLK
MTSR
Clock
Shift Register