Select Mode
| Bits | Description |
|---|
| 7 | 1 if in select mode |
| 1:0 | indicate currently selected device |
| Bits | Description |
|---|
| 7 | 1 to enter select mode, 0 to enter selected device mode (no other bits have effect) |
| 6 | 1 to change selected device |
| 1:0 | selected device |
Xilinx DNA Mode
| Bits | Description |
|---|
| 0 | dna bit (serial stream shifts left) |
| Bits | Description |
|---|
| 7 | 1 to enter select mode (write has no other effect) |
Xilinx XADC Mode (Documented in Xilinx Series 7 UG480)
| Bits | Description |
|---|
| 6 | 1 if XADC is busy with conversion (BUSY) |
| 1 | 1 if XADC conversion completed since last read (EOC, read clears) |
| 0 | 1 if XADC conversion sequence completed since last read (EOS, read clears) |
| Bits | Description |
|---|
| 7 | 1 to enter select mode (write has no other effect) |
| 6 | 1 to reset XADC (RESET) |
| 0 | 1 to start conversion (CONVST) |
Re-enter select mode at any time by writing to the register with bit 7 set
Select a device to communicate with by writing to the register with bits 6 & 7 set
Exit select mode by writing zero to bit 7; thereafter the particular device is attached to the nextreg