This is the first time I'm developing an APB slave. I have some doubts related to APB Protocol. There are three phases such as IDLE, SETUP, and ACCESS as per the state diagram given in the APB spec, but when I want to make a state diagram based on waveform some doubts arise in my mind.
Four combinations are generated based on two input signals and each state has this four-combination logic. I consider four states: IDLE, SETUP, ACCESS, and ERROR.
In ACCESS Current_State, when PSel = 1 and PEnable = 1, then what is the Next_State?
In ERROR Current_State:
PSel = 0 and PEnable = 1,
PSel = 1 and PEnable = 0,
PSel = 1 and PEnable = 1, then which Next_State should I consider for these three combinations?
I know these might be simple doubts, but please help me to clarify these doubts ASAP.
Thanks & Regards,