29.4.2 CLB Software Input Registers

The CLB Software Input registers (CLBSWINU:H:M:L) can be used by user software to provide direct digital inputs to the CLB logic (see Figure 29-10).

Figure 29-10. CLB Software Inputs to the BLE Input Selection Registers

Input register synchronization occurs when CLBSWINL is written by user software. When CLBSWINL is written, the contents of the all four registers are copied into holding latches, the CLBSWIN Register Input Busy (BUSY) bit is set (BUSY = '1'), and the CLBSWINx registers are locked and cannot be modified. Once synchronization is complete, module hardware clears the BUSY bit, and the CLBSWINx registers are unlocked and ready to be modified.

Important: The CLBSWINU, CLBSWINH, and CLBSWINM registers must be written prior to writing the CLBSWINL register, otherwise the current values in each respective register will be latched once CLBSWINL is written.