Embedian, Inc.
148
SMARC-iMX8MM Computer on Module User’s Manual
v. 1.2
module
through
IO
lines
and
disturbs
the
SMARC
module
power
on
sequence.
More
seriously,
it
might
cause
to
the
CPU
won’t
boot
up.
It
is
always
recommended
that
the
power
on
module
has
to
be
earlier
than
that
on
carrier
board.
The
boot
up
of
module
depends
on
when
you
release
the
reset
signal
of
your
carrier
board.
The
module
will
boot
up
when
the
reset
signal
on
your
carrier
board
is
released.
Before
that,
the
module
will
not
boot
up.
That’s
why
designer
needs
to
put
the
RESET_IN#
in
the
last
stage
of
power
to
serve
as
the
"
power
good
"
signal
of
the
carrier
board.
The
module
will
not
boot
up
till
the
module
power
is
ready
because
the
carrier
board
hasn't
released
the
reset
signal
yet.
The
sequence
is
as
follows:
Module
Power
Ready
‐‐
>
CARRIER_POWER_ON
‐‐
>
RESET_IN#
‐‐
>Boot
Up
4.1.5.
RESET_IN#
The
SMARC
module
does
not
know
the
IO
power
status
from
the
carrier
board,
and
put
RESET_IN#
in
the
last
stage
of
power
can
serve
as
the
“
power
good
”
signal
of
carrier
board.
This
also
assures
that
the
power
of
carrier
board
is
good
when
SMARC
module
booting
up.
4.1.6.
VDD_IO
SMARC
1.0
specification
defines
the
I/O
voltage
to
be
1.8V
or
3.3V
or
both.
The
3.3V
VDD_IO
is
depreciated
from
SMARC
1.1
specification.
SMARC
‐
iMX8MM
supports
1.8V
VDD_IO
only.
4.1.7.
Power
Bad
Indication
(VIN_PWR_BAD#)
Power
bad
indication
is
from
carrier
board
and
is
an
input
signal
for
Module.
