KUNBUS-COM EtherCAT
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4.8 Synchronous serial interface
A synchronous serial interface is available to you on the application
interface. To use this interface, you have to set the logical level of pin
a14 to high (3.3 V).
The synchronous serial interface can be used in 2 operating modes.
Select the operating mode you require via the logical level on pin a6:
– 0 (GND) = SPI Slave for connecting to an SPI Master
– 1 (3.3 V) = SSC Master for connecting to a shift register chain
The following pins are available for operating as an SPI Slave for
connecting to an SPI Master:
–
a4
SPI Clock (input)
–
a5
SPI Data in (MOSI, input)
–
b4
SPI Data out (MISO, output)
–
b5
SPI Chip Select (CS, input)
–
b6
SPI ready (output)
The following pins are available for operating as an SSC Master for
connecting to a shift register chain:
–
a4
SSC Clock (output)
–
a5
SSC Data out (MOSI, output)
–
a7
SSC centre tap (MID, input)
–
b4
SSC Data in (MISO, input)
–
b6
SSC Strobe Signal (LOAD, output)
–
b7
SSC Reset (output)
Output data from the Data Broker is written to the SSC output
register area and input data is read from the SSC input register area
in both operating modes. The SPI Slave operating mode also allows
an SPI Master write and read access to all other Memory Register
that are enabled for this. This section describes how this functions in
detail.
Operating mode as SPI Slave
In SPI Slave mode, the transmission of the process data between an
SPI Master and the SSC Input or Output registers takes place in data
blocks, which, in addition to the actual process data, also contain
metadata (e.g. for indicating the register addresses for source and
target areas). Such data blocks are transmitted with a hardware
handshake. The actual data transmission lines MOSI, MISO and
Clock are used with 3.3 V logic in the usual manner, as described
below in the document S12SPIV4 "SPI Block Guide" von Motorola /
Freescale®. Here, you can freely select the normally alterable
Components
