To constrain the optional
osc output pin on ALTUFM_NONE, ALTUFM_I2C, ALTUFM_SPI, and ALTUFM_PARALLEL megafunctions, use either of the following methods:
- Constrain the clock automatically by using the
derive_pll_clockscommand. Note that in addition to creating generated clocks for PLL outputs, the
derive_pll_clockscommand also creates clock constraints for internally-generated clocks.
- Constrain the clock manually by using the following command:
create_clock -period 181.818 -name <name> <hierarchical path to ufm_block>|osc
- Although actual output frequency may vary, constraining the
oscpin to 181.818 ns (5.5 MHz) ensures the clock is analyzed at its minimum possible period (maximum possible frequency).