Seco SM-C12 User Manual page 27

Smarc rel. 2.0 compliant module with nxp i.mx 8m applications processors

Table of Contents

3.2.1.5 SDI/O interface signals

The NXP i.MX 8M processors offer many different SDIO interfaces, that can be used independently one from the other to implement different mass storages (internal

eMMC, internal SD Card, external SDI/O interface).

The SDIO1 signals of the processor are used for the onboard eMMC storage of the SM-C12 module.

When the SM C12 module is without an onboard wireless module, the SDIO2 interface of the processor is externally accessible through the edge connector of the

module. Supporting 4-bit mode as per the SMARC specification.

The uSDHC controller complies with:

•

SD Host Controller Standard Specification version 3.0 with 50 MHZ SDR signaling to support up to 25MB/sec (High Speed Mode)

•

MMC System Specification version 5.0

The edge accessible SDIO2 signals are as follows:

SDIO_WP: Write Protect bidirectional signal, electrical level +3.3V_S. It is used to communicate the status of Write Protect switch on external SD/MMC card.

SDIO_CMD: Command/Response line. Bidirectional signal, electrical level +3.3V_S, used to send command from Host (i.MX 8M processor) to the connected card,

and to send the response from the card to the Host.

SDIO_CD#: Card Detect Input. Active Low Signal, electrical level +3.3V_S with 10kΩ pull-up resistor. This signal must be externally pulled low to signal that a

SDIO/MMC Card is present.

SDIO_CK: Clock Line (output), 52MHz maximum frequency for MMC High Speed Mode, 50 MHz maximum frequency for SD/SDIO High Speed Mode.

SDIO_PWR_EN: SDIO Power Enable output, active low signal, electrical level +3.3V_S. It is used to enable the power line supplying SD/SDIO/MMC devices.

SDIO_[D0÷D3]: SDIO data bus. Signals for 4-bit SD/SDIO/MMC communication mode. The 8-bit MMC communication mode is unsupported.

As a factory alternative, the above set of signals are instead routed to an onboard WiFi/BT controller.

SM-C12

Table of Contents