Quectel EC21 Series

LTE Standard Module Series
EC21_Series_Hardware_Design
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3.13. SD Card Interface
EC21 series module supports SDIO 3.0 interface for SD card. The following table shows the pin
definition of SD card interface.
Table 15: Pin Definition of SD Card Interface
Pin Name Pin No. I/O Description Comment
SDC2_DATA3 28 DIO SD card SDIO data bit 3
SDIO signal output voltage can
be selected according to the
signal output voltage supported
by SD card, see SD 3.0 protocol
for more details.
If unused, keep them open.
SDC2_DATA2 29 DIO SD card SDIO data bit 2
SDC2_DATA1 30 DIO SD card SDIO data bit 1
SDC2_DATA0 31 DIO SD card SDIO data bit 0
SDC2_CLK 32 DO SD card SDIO clock
SDC2_CMD 33 DIO SD card SDIO command
VDD_SDIO 34 PO SD card SDIO pull-up power
1.8/2.85 V power domain.
Configurable power supply.
Cannot be used for SD card
power supply.
If unused, keep it open.
SD_INS_DET 23 DI SD card insertion detect
1.8 V power domain.
If unused, keep it open.
The following figure shows a reference design of SD card.
Figure 25: Reference Circuit of SD Card Interface