In an integrated circuit such as a programmable logic device (PLD) (e.g., a field programmable gate array (FPGA), a complex programmable logic device (CPLD), a field programmable system on a chip (FPSC), or other type of programmable device), control registers may be used to store bit values to select various operational settings, such as manufacturing settings or trim settings.
Existing PLDs may use one or more large registers to store bit values for multiple unrelated settings. For example, a single register may store multiple data fields (e.g., sets of one or more bit values), with each data field corresponding to different unrelated manufacturing or trim settings. However, conventional implementations of registers and related circuitry are often limited in the way that stored bit values may be updated, particularly if data in only a single data field of a register is to be updated.
In one approach, to change a single data field in a conventional register, the changed data field and all remaining data fields of the register typically must be provided again to the PLD and reloaded into the register. This may require an operator to store or otherwise recall all data fields of the register externally to the PLD and subsequently provide all data fields again to the PLD, regardless of how many data fields are actually changed. Such implementations may be problematic when the operator may know the values of one or more data fields to be changed, but may not know the values of other data fields that should not be changed (e.g., data fields with bit values provided by other operators or other parties).
In another approach, multiple access methods (e.g., instructions or addresses) may be used to update specific data fields within a large register. But such an approach may require extensive circuitry which may not scale economically as the number of data fields increases.
As a result, there is a need for an improved approach to changing specific data fields in a register that overcomes one or more of the problems associated with existing approaches.