User Manual
664
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
High-Speed Synchronous Serial Interface SSC1/SSC2
21.3.4
Half-Duplex Operation
In a Half-Duplex Mode, only one data line is necessary for both receiving
and
transmitting of data. The data
exchange line is connected to both the MTSR and MRST pins of each device, the shift clock line is connected
to the SCLK pin.
The master device controls the data transfer by generating the shift clock, while the slave devices receive it.
Due to the fact that all transmit and receive pins are connected to the one data exchange line, serial data may
be moved between arbitrary stations.
Similar to Full-Duplex Mode, there are two ways to avoid collisions on the data exchange line:
• Only the transmitting device may enable its transmit pin driver
• The non-transmitting devices use open drain output and send only ones.
Because the data inputs and outputs are connected together, a transmitting device will clock in its own data
at the input pin (MRST for a master device, MTSR for a slave). By this method, any corruptions on the common
data exchange line are detected if the received data is not equal to the transmitted data.
Figure 180 SSC Half-Duplex Configuration
21.3.5
Continuous Transfers
When the transmit interrupt request flag is set, it indicates that the transmit buffer TB is empty and ready to
be loaded with the next transmit data. If TB has been reloaded by the time the current transmission is finished,
the data is immediately transferred to the shift register and the next transmission will start without any
additional delay. On the data line, there is no gap between the two successive frames. For example, two byte
transfers would look the same as one word transfer. This feature can be used to interface with devices that can
operate with or require more than 8 data bits per transfer. It is just a matter of software, how long a total data
frame length can be. This option can also be used to interface to byte-wide and word-wide devices on the
same serial bus, for instance.
Master
Device #1
Shift Register
Clock
MTSR
CLK
MRST
MRST
CLK
MTSR
Clock
Shift Register
Device #2
Slave
Common
Transmit/
Receive
Line
Slave
Device #3
MRST
CLK
MTSR
Clock
Shift Register
Transmit
Clock