M12 Hardware Design
M12_Hardware_Design_V3.3
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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
Module
SD_DATA
SD_CLK
SD_CMD
DATA2
DATA1
DATA0
CD/DATA3
CMD
VSS1
VDD
CLK
VSS2
47K
47K
47K
4.7uF
0.1nF
VDD_EXT
33R
33R
33R
SD Socket
1
2
3
4
5
6
7
8
9
Figure 43: Reference circuit of SD card
Name
Pin
Function
SD_DATA
1
Data output and input signal of SD card
SD_CLK
2
Clock signal of SD card output
SD_CMD
3
Command signal of SD card output
Quectel
Confidential