I2C And Pcm Interfaces - Quectel EG915U Series Hardware Design

⚫
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with surrounded ground.
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To offer good ESD protection, it is recommended to add a TVS diode array of which the parasitic
capacitance should be less than 15 pF. Add 0 Ω resistors in series between the module and the
(U)SIM card to facilitate debugging. The 33 pF capacitors are used for filtering interference of
EGSM900. Additionally, keep the (U)SIM peripheral circuit close to the (U)SIM card connector.
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The pull-up resistor on USIM_DATA can improve anti-jamming capability of the (U)SIM card. If the
(U)SIM card traces are too long, or the interference source is relatively close, it is recommended to
add a pull-up resistor near the (U)SIM card connector.

4.5. I2C and PCM Interfaces

The module provides one I2C interface and one pulse code modulation (PCM) interface. The PCM
interface of the module only supports slave mode; therefore, the clock signal of the codec IC needs to be
provided externally.
Table 13: Pin Definition of I2C and PCM Interfaces
Pin Name Pin No.
I2C _SCL 40
I2C _SDA 41
PCM_DIN 6
PCM_DOUT 7
PCM_SYNC 5
PCM_CLK 4
The following figure shows a reference design of PCM interface with external codec IC.
EG915U_Series_Hardware_Design
I/O Description
OD I2C serial clock
OD I2C serial data
DI PCM data input
DO PCM data output
DI PCM data frame sync
DI PCM clock
LTE Standard Module Series
Comment
External pull-up resistor is required.
1.8 V only. If unused, keep it open. If
the I2C interface is used to connect
to external codec, it cannot connect to
other external devices.
1.8 V power domain.
If unused, keep it open.
Support slave mode only.
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