Embedian, Inc.
149
SMARC-FiMX6 Computer on Module User’s Manual v.1.2
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. However,
many users still preferred 3.3V
VDD_IO
because it is easier for carrier
design.
SMARC-FiMX6
supports 1.8V or 3.3V
VDD_IO
. If the Carrier supports only
1.8V I/O, then the Carrier will tie the
VDD_IO_SEL#
pin directly to GND. If
the Carrier supports only 3.3V
VDD_IO
, Carriers will float the signal for 3.3V.
3.3V SMARC-FiMX6
will not power up if module senses a 1.8V
VDD_IO
Carrier on the
VDD_IO_SEL#
(due to the Carrier pulling the line down) to
protect the module. It will cut the module power down if
VDD_IO_SEL#
is
connected to GND (this is the case of 1.8V
SMARC
module).
4.1.7. Power Bad Indication (VIN_PWR_BAD#)
Power bad indication is from carrier board and is an input signal for Module.
Module and Carrier power supplies (other than Module and Carrier power
supervisory circuits) will not be enabled while this signal is held low by the
Carrier.
This signal has a 100K pull-up on module and is driven by OD part on
Carrier.