6574 - MachXO2/MachXO3: Why is the IO state locked during TransFR Operation of MACHXO3 device?
Description:
The IO electrical properties like Drive strength, Slew, Open-Drain, and Pullmodes are preserved (carried over) from the initial configuration.
These settings are not cleared unless the device is Power-cycled or loaded with a new bitstream to overwrite these
settings. In this case, since we have enabled TransFR, while the new bitstream is being loaded, only the internal
fabric is changed, but the IO settings from the initial programming will still be preserved. Though the new bitstream is
loaded, the IO settings will not change until the device is power-cycled. Any other reinitialization techniques like
toggling PROGRAMN, Issuing REFRESH, or Erase SRAM commands will not clear the IO settings in this case, and only the
Power-cycling (Power-off then Power-on) the device will ensure that the new bitstream settings for the IOs, have taken effect.
This behavior is true for MachXO2 and MachXO3 family as well since these two families only support non-JTAG mode TransFR.
Solution:
For the new IO electrical properties to take effect, it is required to perform a power-cycle. This is a known device limitation and there is no plan to fix it.
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