User's Manual

Smart Machine Smart Decision
SIM868_Hardware_Design_V1.00 39 2016-06-20
4.9. SD Interface
SD interface can be configured as PCM interface; the following table shows the detailed multiplexing function.
Table 20: SD multiplexing function
Pin name Pin number Mode 0(default) Mode 1 Mode 2 Mode 3
MCCA3 46 MCCA3 DAIPCMOUT(1.8V) GPIO EINT19
MCCA2 47 MCCA2 DAICLK(1.8v) GPIO EINT18
MCCA1 48 MCCA1 DAIPCMIN(1.8v) GPIO EINT17
MCCA0 49 MCCA0 DAISYNC (1.8v) GPIO
MCCK 50 MCCK GPIO
MCCM0 51 MCCM0 GPIO
Note: Customer can use AT command set mode. For detail, please refer to document [1].
SIM868 provides a hardware SD interface:
Figure 34: SD reference circuit
If power supply is 2.8V for SD card, customer can use VDD_EXT; if power supply is 3.3V, please use external
design LDO.
4.10. I2C Bus
The SIM868 provides an I2C interface which is only used in the embedded AT application.
Table 21: Pin definition of the I2C
Note:
1. I2C should be pulled up to 2.8V via 4.7K externally.
2. I2C function is not supported in the standard firmware. If you need, please contact SIMCom.
4.10.1. I2C Multiplexing Function
Table 22: I2C multiplexing function
Pin name Pin number Description
SCL 65 I2C serial bus clock(open drain output)
SDA 64 I2C serial bus data(open drain output)