SM-B79
SM-B79 User Manual - Rev. First Edition: 1.0 - Last Edition: 1.0 - Author: A.R - Reviewed by M.B. - Copyright © 2021 SECO S.p.A.
48
3.3.10
microSD Slot
According to SMARC
®
Rel. 2.1.1 specification, SMARC
®
module can support signals for Secure Digital Input/Output
and MultiMedia cards over the SMARC
®
SDIO interface, for the use of standard SD or MMC cards, to be used as Mass
Storage Device and/or Boot Device (if the SMARC
®
module used with SM-B79 implements this functionality).
Please refer to the User Manual of the used SMARC
®
module for information about Card types supported by the chipset.
The connector is a microSD connector, push-push type, H=1.68 mm, type JST DM3AT-SF-PEJM5 or equivalent.
Signal Description:
SDIO_CD#: Card Detect Input, indicating when a SDIO/MMC card is present
SDIO_CK: SD Clock Line (output)
SDIO_CMD: Command/Response bidirectional line, used for card initialization and for
command transfers.
SDIO_D[0÷3]: SD Card data bus, SDIO_D0 signal is used for all communication mode, SDIO_D[1÷3] signals are
required for 4-bit communication mode
SDIO_PWR voltage is derived from +3.3V_ALW power rail. It can be switched on and off via SW (SDIO_PWR_EN signal,
managed directly by the SMARC
®
module).
For ESD protection, on all signal lines are placed clamping diodes for voltage transient suppression.
Since microSD cards do not support the Write Protect functionality, which is instead
supported by SMARC
®
module, then on SM-B79 carrier board it is available a 2-way
jumper, JP5, which allows forcing Write Protect signal input SDIO_WP, directly managed
by the SMARC
®
module
microSD Card Slot CN77
Pin
Signal
1
SDIO_D2
2
SDIO_D3
3
SDIO_CMD
4
SDIO_PWR
5
SDIO_CK
6
GND
7
SDIO_D0
8
SDIO_D1
CardDetect
SDIO_CD#
JP5 position
SDIO Write Protect
Not inserted
WP Enabled: microSD card cannot be written
Inserted
WP Disabled: microSD card can be written