The Phase Generator consists of an accumulator followed by an optional adder to allow the addition of a phase offset. When the core is customized, the phase increment (PINC) and phase offset (POFF) can be independently configured to be either fixed, programmable (using the CONFIG channel), or streaming (using the input PHASE channel).
When set to fixed, the DDS output frequency is set when the core is customized and cannot be adjusted after the core is embedded in a design.
When set to programmable, the CONFIG channel TDATA field has a subfield for the input in question (PINC or POFF) or both if both have been selected to be programmable. If neither PINC nor POFF is set to programmable, there is no CONFIG channel.
When set to streaming, the input PHASE channel TDATA field has a subfield for the input in question (PINC or POFF) or both if both have been selected to be streaming. If neither PINC nor POFF is set to streaming, and the core is configured to have a Phase Generator, there is no input PHASE channel.
When PINC is set to streaming, an optional RESYNC streaming input can be configured. When asserted, this signal resets the accumulated phase of the channel in question.
When rasterized mode is selected, the hardware values of PINC and POFF that are input or configured must be 0 to Modulus-1. This corresponds to a full circle. For negative PINC or POFF values, add the Modulus to the negative value desired to map to the required range. For example, with Modulus = 100, the required range is 0 to 99. An angle of -90° would be -25 with this Modulus. Adding 100 gives 75 (270°).
When using system parameters, PINC and POFF are not input directly, but are calculated from the input output frequencies and phase angles. Be aware that for small values of Modulus, the available values are relatively far apart, so the actual output frequency or phase angle might differ significantly from the desired value as displayed in the Additional Summary tab.