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3.7.2. XTAL_IN/OUT
The XTAL_IN and XTAL_OUT pins are external crystal pins, and the recommended crystal frequency is
37.4 MHz. These pins are optional pins, and the crystal position has been reserved inside the module,
and customers can choose according to their needs.
The following table is the recommended crystal parameters. It is recommended that customers select the
crystal according to the following table:
Table 17: XO Parameter Definition
Parameter
Frequency
load capacitance
ESR
Drive level
Frequency tolerance Initial
+ over temperature
3.7.3. SDIO_VSEL
SDIO_VSEL is SDIO mode selection pin, the following table shows the pin definition of SDIO_VSEL.
Table 18: Pin Definition of SDIO_VSEL
Pin Name
Pin No.
SDIO_VSEL
29
3.7.4. GPIOs
GPIO1/GPIO2 are function configuration pins, which can be used to enter JTAG mode. Please contact
QUECTEL if necessary. FC905A offers 4 GPIOs by default:
FC905A_Hardware_Design
Min
Typ.
-
37.4
-
16
-
-
200
-
-20
-
I/O
Description
SDIO mode selection
DI
1.8 V: pull-up by default
3.3 V: pull-down and connect to GND through 10 kΩ resistor
Wi-Fi&Bluetooth Module Series
Max
Unit
-
MHz
-
pF
Ω
60
μW
-
20
ppm
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