Input/Output

I/O banks and special functions

Virtex 6 devices have a very regular I/O bank structure. There are up to four I/O columns in the device:

• outer left (sometimes present)
• inner left (always present)
• inner right (always present)
• outer right (sometimes present)

These columns consist entirely of IO tiles, with one tile per two interconnect rows. Every tile contains two I/O pads: IOB0 and IOB1. IOB0 is located in the bottom row of the tile, while IOB1 is located in the top row. Every I/O bank consists of exactly one region, or 40 I/O pads. The banks are numbered as follows:

• the bank in region c + i of outer left column (where c is the region containing the top half of the CFG tile) has number 15 + i
• the bank in region c + i of inner left column has number 25 + i
• the bank in region c + i of inner right column has number 35 + i
• the bank in region c + i of outer right column has number 45 + i

All IOBs in the device are grouped into differential pairs, one pair per IO tile. IOB1 is the "true" pin of the pair, while IOB0 is the "complemented" pin. Differential input and true differential output is supported on all pins of the device.

IOB1 pads in the 8 rows surrounding the HCLK row (that is, rows 17, 19, 21, 23) are considered "clock-capable". They can drive BUFIODQS buffers via dedicated connections. The ones in rows 19 and 21 can drive BUFR buffers in this and two surrounding regions, and are considered "multi-region clock capable", while the ones in rows 17 and 23 are considered "single-region clock capable". While Xilinx documentation also considers corresponding IOB0 pads clock-capable, this only means that they can be used together with IOB1 as a differential pair.

There are 8 IOB1\ s that are considered "global clock-capable" and can drive BUFGCTRL global buffers via dedicated interconnect. They are:

• bank 24 rows 37, 39
• bank 25 rows 1, 3
• bank 34 rows 37, 39
• bank 35 rows 1, 3

The IOB0 in rows 10 and 30 of every region is capable of being used as a VREF pad.

Each bank has two IOBs that can be used for reference resistors in DCI operation. They are both located in the same I/O tile, with VRP located on IOB0 and VRN located on IOB1. The relevant tile is located as follows:

• bank 24: rows 4-5
• bank 34: rows 0-1
• banks 15, 25, 35: rows 6-7
• all other banks: rows 14-15

In parallel or SPI configuration modes, some I/O pads in banks 24 and 34 are borrowed for configuration use:

• bank 24 row 6: CSO_B
• bank 24 row 7: RS[0]
• bank 24 row 8: RS[1]
• bank 24 row 9: FWE_B
• bank 24 row 10: FOE_B/MOSI
• bank 24 row 11: FCS_B
• bank 24 row 12: D[0]/FS[0]
• bank 24 row 13: D[1]/FS[1]
• bank 24 row 14: D[2]/FS[2]
• bank 24 row 15: D[3]
• bank 24 row 24: D[4]
• bank 24 row 25: D[5]
• bank 24 row 26: D[6]
• bank 24 row 27: D[7]
• bank 24 row 28: D[8]
• bank 24 row 29: D[9]
• bank 24 row 30: D[10]
• bank 24 row 31: D[11]
• bank 24 row 32: D[12]
• bank 24 row 33: D[13]
• bank 24 row 34: D[14]
• bank 24 row 35: D[15]
• bank 34 row 2: A[16]
• bank 34 row 3: A[17]
• bank 34 row 4: A[18]
• bank 34 row 5: A[19]
• bank 34 row 6: A[20]
• bank 34 row 7: A[21]
• bank 34 row 8: A[22]
• bank 34 row 9: A[23]
• bank 34 row 10: A[24]
• bank 34 row 11: A[25]
• bank 34 row 12: D[16]/A[0]
• bank 34 row 13: D[17]/A[1]
• bank 34 row 14: D[18]/A[2]
• bank 34 row 15: D[19]/A[3]
• bank 34 row 24: D[20]/A[4]
• bank 34 row 25: D[21]/A[5]
• bank 34 row 26: D[22]/A[6]
• bank 34 row 27: D[23]/A[7]
• bank 34 row 28: D[24]/A[8]
• bank 34 row 29: D[25]/A[9]
• bank 34 row 30: D[26]/A[10]
• bank 34 row 31: D[27]/A[11]
• bank 34 row 32: D[28]/A[12]
• bank 34 row 33: D[29]/A[13]
• bank 34 row 34: D[30]/A[14]
• bank 34 row 35: D[31]/A[15]

The SYSMON present on the device can use up to 16 IOB pairs as auxiliary analog differential inputs. The VPx input corresponds to IOB1 and VNx corresponds to IOB0 within the same tile. If the device has a outer left IO column, the IOBs are located in banks 15 and 35; otherwise, they are located in banks 25 and 35. The IOBs are in the following tiles:

• VP0/VN0: bank 35 rows 34-35
• VP1/VN1: bank 35 rows 32-33
• VP2/VN2: bank 35 rows 28-29
• VP3/VN3: bank 35 rows 26-27
• VP4/VN4: bank 35 rows 24-25
• VP5/VN5: bank 35 rows 14-15
• VP6/VN6: bank 35 rows 12-13
• VP7/VN7: bank 35 rows 8-9
• VP8/VN8: bank 15/25 rows 34-35
• VP9/VN9: bank 15/25 rows 32-33
• VP10/VN10: bank 15/25 rows 28-29
• VP11/VN11: bank 15/25 rows 26-27
• VP12/VN12: bank 15/25 rows 24-25
• VP13/VN13: bank 15/25 rows 14-15
• VP14/VN14: bank 15/25 rows 12-13
• VP15/VN15: bank 15/25 rows 8-9

The devices also have dedicated configuration bank 0, which has no user I/O and is located in the CFG tile. It has the following pins:

• CCLK
• CSI_B
• DIN
• DONE
• DOUT_BUSY
• HSWAPEN
• INIT_B
• M0, M1, M2
• PROGRAM_B
• RDWR_B
• TCK, TDI, TDO, TMS

Bitstream — IO