16.7
Output Inversion
When configured as an output (either software or IOF controlled), the software-writable
out_xor
register is combined with the output to invert it.
16.8
HW I/O Functions (IOF)
Each GPIO pin can implement up to 2 HW-Driven functions (IOF) enabled with the
iof_en
reg-
ister. Which IOF is used is selected with the
iof_sel
register.
When a pin is set to perform an IOF, it is possible that the software registers
port
,
output_en
,
pullup
,
ds
,
input_en
may not be used to control the pin directly. Rather, the pins may be con-
trolled by hardware driving the IOF. Which functionalities are controlled by the IOF and which
are controlled by the software registers are fixed in the hardware on a per-IOF basis. Those that
are not controlled by the hardware continue to be controlled by the software registers.
If there is no IOFx for a pin configured with IOFx, the pin reverts to full software control.
Chapter 16 General Purpose Input/Output Controller
SiFive FE310-G000 Manual: v3p2
© SiFive, Inc.
Page 75
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