Sd Card Interface - Quectel M12 Hardware Design

M12 Hardware Design

3.16. SD card interface

The module provides SD card interface that supports many types of memory, such as Memory
Stick, SD/MCC card and T-Flash or Micro SD card. The following are the main features of SD
card interface:

Only supports 1bit serial mode

Do not support the SPI mode SD/MMC memory card

Do not support multiple SD memory cards

Do not support hot plug

The data rate up to 26MHz in serial mode

Up to 32GB maximum memory card capacity
Based on the interface features and reference circuit of SD card shown in figure 43, the users can
easily design the SD card application circuit to enhance the memory capacity of the module. The
users can store some high-capacity files to external memory card. Such as in the automotive
application system, the module can record and store the audio file to the SD card, and also can
play the audio files in SD card.
Table 22: Pin definition of the SD card interface
Name
SD_DATA
SD_CLK
SD_CMD
Module
SD_CMD
SD_CLK
SD_DATA
M12_Hardware_Design_V3.3
Pin Function
1 Data output and input signal of SD card
2 Clock signal of SD card output
3 Command signal of SD card output
VDD_EXT
33R
33R
33R
4.7uF
Figure 43: Reference circuit of SD card
47K 47K 47K
9
1
2
3
VSS1
4
VDD
5
6
7
8
0.1nF
SD Socket
DATA2
CD/DATA3
CMD
CLK
VSS2
DATA0
DATA1
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