Configuration Register Read Procedure (SelectMAP) - Configuration Register Read Procedure (SelectMAP) - UG570

UltraScale Architecture Configuration User Guide (UG570)
Document ID
UG570
Release Date
2025-03-04
Revision
1.20.1 English

The simplest read operation targets a configuration register such as the COR0 or STAT register. Any configuration register with read access can be read through the SelectMAP interface, although not all registers offer read access. The procedure for reading the STAT register through the SelectMAP interface follows:

  1. Write the bus width detection sequence and synchronization word to the device followed by at least one NOOP.
  2. Write the read STAT register packet header to the device.
  3. Write two NOOP commands to the device to flush the packet buffer.
  4. Read one word from the SelectMAP interface; this is the Status register value.
  5. Write the DESYNC command to the device.
  6. Write two dummy words to the device to flush the packet buffer.

See the following table for command sequence.

Table 1. Status Register Readback Command Sequence (SelectMAP)
Step SelectMAP Port Direction Configuration Data Explanation
1 Write FFFFFFFF Dummy word
2 Write 000000BB Bus width sync word
3 Write 11220044 Bus width detect
4 Write FFFFFFFF Dummy word
5 Write AA995566 Sync word
6 Write 20000000 NOOP
7 Write 2800E001 Write Type 1 packet header to read STAT register
8 Write 20000000 NOOP
9 Write 20000000 NOOP
10 Read SSSSSSSS Device writes one word from the STAT register to the configuration interface
11 Write 30008001 Type 1 Write 1 word to CMD
12 Write 0000000D DESYNC command
13 Write 20000000 NOOP
14 Write 20000000 NOOP

You must change the SelectMAP interface from write to read control between steps 9 and 10, and back to write control after step 10.

To read registers other than STAT, the address specified in the Type 1 packet header in step 7 of the previous table should be modified and the word count changed if necessary. Reading from the FDRO register is a special case that is described in Configuration Memory Read Procedure (SelectMAP).