Question about FlexIO State Machine outputs

D

DrItanium

Member
I am currently using FlexIO1 and FlexIO2 in state machine mode to detect various aspects of the i960Sx memory transaction (using a teensy 4.1). FlexIO1 is used to identify when the i960Sx goes into a memory transaction. FlexIO2 is used to convert the Ready pulse sent to the i960 into a ready level. In both cases, I am using the PIN register of the FlexIO to check the output pins to know when to continue on [interrupts provided by the FlexIO4_t4 library are too slow for my purposes and eat into the i960's coremark score]. Thus the output pins I am reserving are going to waste as I just care about the result and not connecting it to something else. So here is what I'm curious about:
  1. Do you have to configure the corresponding GPIO for FlexIO mode to have it show up when I read the PIN register?
    1. Is it enough to configure the state machine outputs in SHIFTCFGn?
  2. With the exception of EMC_02, is it safe to use unmapped FlexIO pins (EMC_00, EMC_01, EMC_03, GPIO_B0_04..7) as state machine outputs?
 
Individual pin mux doesn't need to be set to FlexIO unless you want it to read/drive that physical pin, the FlexIO state register is the internal state.
 
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