The Input Interface
The input to the system is a very simple process. Data is received from an external device. Communication between these devices is managed using PMC's PL3 interface. The data received via this interface is then stored in an input queue. This input queue stores the incoming data until it is needed by the system. This queue is wide enough so that at least one full frame can fit inside of it. If the queue nears its maximum capacity, an alarm is sent to the transmitting device signaling a stop in transmission. If the transmitting device does not stop transmission, the data will be lost. The alarm signal is used to ensure that no data is lost, as long as the transmitting device takes the appropriate action when an alarm is received. For more information on the different parts of this input interface, select the respective parts of the diagram below. Following is a high level description of the input module in our device.
The data coming in from the external device (test bench) is passed through an input state machine which uses the PL3 interface to transfer and store data into the input queue. The input queue then stores this data until it is required by the rest of the system.