peb20534h-52 Infineon Technologies Corporation, peb20534h-52 Datasheet - Page 122

• Manufacturer Part Number: peb20534h-52
• Description: Dma Supported Serial Communication Controller With 4 Channels
• Manufacturer: Infineon Technologies Corporation

PEB 20534
PEF 20534
Multi Function Port (MFP)
The same mechanism as for selecting a slave for transmission (separate select lines or
special commands) may also be used to promote 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 (SSCMS) and the direction of their port pins (see
description above).
Chip Select Control:
There are 4 chip select pins associated with the SSC port: MCS0 to MCS3. The four chip
select lines are automatically activated at the beginning of a transfer and deactivated
again after the transfer has ended. Activation of a chip enable line always begins one
half bit time before the first data bit is output at the MTSR pin, and the deactivation
(except for the continuous transfers) is performed one half bit time after the last bit of the
transfer has been transmitted/received completely.
The chip select lines are selected by the control bits ASEL0 to ASEL3 of the SSC Chip
Select Enable register SSCCSE (refer to
Page
364). By setting any of these bits to 0, the
corresponding chip select port will be asserted when transmitting data. All other bits of
the SSCCSE register have to be set to ‘0‘.
6.2.1.3
Operational Mode: 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 pins MTSR and MRST
of each device, the clock line is connected to the MCLK 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). This allows
to detect any corruptions on the common data exchange line, where the Rx data is not
equal to the Tx data.
Data Sheet
122
2000-05-30