Sundance SMT148 - Manual (Page 22)

Version 1.4 Page 22 of 35 SMT148 User Manual
Destination
Any input node to the switch fabric can access the ComPort interface. Please note
that a ComPort is a bi-directional bus. However it is not possible to transfer data in
both directions at the same time. Therefore, if some activity has been detected on the
input path to the switch fabric, the output path, if accessed, will raise its full flag when
it cannot accept data anymore (i.e., when its FIFO is full).
The ComPort interface must first receive a 32-bit word of settings In order to be able
to start transmitting the data it will receive.
Bit 31: never ending transfer if 1. This setting can be useful when the connection
needs to always be enabled such as the case the ADC streams its data to the same
DSP via one of his ComPorts. This bit must be set to 0 if the ComPort needs to be
dynamically reconnected to another node at some stage.
Bit 23 down to 0: transfer length. This is the total number of 32-bit words that will be
sent to the ComPort interface (excluding this word). This gives a maximum transfer
length of 2^26-4 bytes (64Mbytes). When the ComPort interface has received all data
it expected it will disconnect itself from the input node by sending a done pulse to the
switch fabric. This setting is ignored if bit 31 is set to 1.