IPU Data Channel

Data Format

The request to start readout of the data of a specific event is the same as the trigger information delivered on the LVL1 trigger channel - a single TRM packet aka a short transfer:

Positions in the network packet are as follows:

Bits	Content
47 - 40	Additional Information
39 - 32	Random Data
31 - 16	16 bit counter
3 - 0	Type

Word	15-12	11-8	7-4	3-0
F0	reserved (CRC)
F1	add. information		random code
F2	trigger number
F3	0	seq. no.		type

The type and additional information are not yet defined and set to 0.

Application Interface

The ipudata-Entity provides an interface to the internal logic to handle all readout requests.

Name	Width	Description
IPU_TRG_NUMBER_OUT	16	Number of the Event to be read out
IPU_READOUT_OUT	1	data on trb_number is valid during high. Is raised after request is received and reset after readout_finished
IPU_DATA_IN	32	Data input for event data
IPU_DATAREADY_IN	1	Datavalid strobe for data_in (offered data is accepted, when read is high in the same clock cycle)
IPU_READ_OUT	1	Interface is able to accept data
IPU_READOUT_FINISHED_IN	1	End of transfer by application
IPU_LENGTH_IN	16	The length of the upcoming data transfer.
IPU_ERROR_PATTERN_IN	32	Errorbits generated by application.

• The required format for the sent data stream is described in TrbNetStreamedEventBuilding.

• The trigger random code is transfered with the request packet, but is not offered to the application - otherwise its function as additional security is lost. All entities despite the application are then able to check the code, but the application is forced to save the code as a proof of authenticity.

• The read signal will be low for one clock cycle after each dataready due to the conversion from 32 to 16 bit word size.

• Length must be valid during the first dataready signal, error pattern must be valid while readout_finished is high

• Readout of an Event containing three data words on an IPU channel endpoint: