SDA6000 Datasheet, PDF (240/380 Pages) Infineon Technologies AG – Teletext Decoder with Embedded 16-bit Controller

SDA 6000
Peripherals
The same mechanism as for selecting a slave for transmission (separate select lines or
special commands) may also be used to move the role of the master to another device
in the network. In this case the previous master and the future master (previous slave)
will have to toggle their operating mode (SSC0MS) and the direction of their port pins.
7.4.2 Half Duplex Operation
In a half duplex configuration 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 in each device, the 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 only send ones.
Since 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
these means any corruptions on the common data exchange line, where the received
data is not equal to the transmitted data are detected.
Users Manual
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2000-06-15