AlgoShiftRegister.vhd File Reference

Algorithm input-data shift register. More...

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Entities
AlgoShiftRegister	entity
	Algorithm input-data shift register. More...
Behavioral	architecture
	Algorithm input-data shift register. More...

Detailed Description

Algorithm input-data shift register.

Here is a detailed description of the input shift register. This module handles the data distribution to the 8 ACs within 5 clock cycles. All the input data are loaded in parallel into a shift register at the beginning of every BC. Then data are shifted at 200 MHz at every rising edge of the clock.

The algorithm logic is connected only to the first 3 locations of the shift register, so that the same data that served as environment (location 2) is then used as core (location 1) and finally as environment again (location 0) before being discarded.

On every 200MHz clock cycle, data “moves” in the Eta direction, so each of the 8 ACs handles always the same Phi but a value of Eta 0.1 higher on each of the 5 clock cycles.

The shift register has the capability to handle peripherical regions. This is done by filling with dummy doata (zeroes) the regions for which data is not provided by the calorimeter, i.e. the first or last Eta column.

In order to do this this module needs to know if the eFEX board is located on the right border (high Eta values) or on the left Border (low Eta values). This is done through the LeftRight port.

• If the value of LeftRight port is '0' the eFEX board is locatd on the left so the first column in the shift register will be filled with dummy data.
• If the value of LeftRight port is '1' the eFEX board is locatd on the right so the last column in the shift register will be filled with dummy data. If the eFEX module is not located in a border region, it is recomended to set this value to 1 and ignore the TOBs produced during the last 200 MHz clock cycle

A representation of the shift register

In the picture above you can see a graphical representation of the input data shift register. On the top, a graphical view of the trigger towers is shown. Orange towers are core and green are environment. As depicted by the black borders, the core towers are also used as environment. The blue column at the far right represents dummy data.

On the bottom, the concept from the point of view of the shift register is shown. YOu can see that on the first clock cycle the SR is loaded and the it is shifted for 4 more clock cycles. The algorithm logic is connected to the first 3 locations of the SR, represented in colour.

Here is a table of input Tower numbering

ST00	ST01	ST02	ST03	ST04	ST05
09	19	29	39	49	59
08	18	28	38	48	58
07	17	27	37	47	57
06	16	26	36	46	56
05	15	25	35	45	55
04	14	24	34	44	54
03	13	23	33	43	53
02	12	22	32	42	52
01	11	21	31	41	51
00	10	20	30	40	50

Author

Francesco Gonnella

Definition in file AlgoShiftRegister.vhd.