AR# 4394: Foundation F1.5: Selecting the default FSM encoding scheme for Express HDL designs
AR# 4394
Foundation F1.5: Selecting the default FSM encoding scheme for Express HDL designs
Description
Keywords: FSM, Foundation Express, CPLD, FPGA, one-hot, binary, encoding
Urgency: Standard
General Description: There are two Finite State Machine encoding styles available in Express: one-hot and binary. The current default is one-hot encoding, but the CPLD archtecture (XC9500) exhibits better performance using binary encoding.
Solution
For CPLD devices, select Synthesis -> Options and set FSM Synthesis: Default Encoding to "Binary".
The encoding style is determined upon analysis of the HDL source, so if HDL files have already been added to the project, you must also select Synthesis -> Force Analysis of All HDL Source Files for this change to take effect.