Wi-Fi&Bluetooth Module Series
FC909A_Hardware_Design 24 / 49
Figure 5: SDIO Interface Connection
To ensure that the interface design complies with the SDIO 2.0 specification, the following principles are
recommended to be adopted:
Route the SDIO traces in inner-layer of the PCB and the impedance is controlled
at 50 Ω ±10 %.
SDIO signals need to be kept away from sensitive signals, such as radio frequency, analog signals,
clocks, and DC-DC noise signals.
SDIO_DATA
2 requires an external 10 kΩ resistor to be pulled up to VDDIO, and maintains a high
level during the process of powering on the FC909A.
SDIO signal traces need to be treated with equal length (the distance between the traces is less than
1 mm).
The distance between SDIO signals and other signals must be greater than 2 times the trace width,
and the busload capacitance must be less than 15 pF.
The maximum length of the internal wiring of the SDIO interface is 5.71 mm.
3.4.2. WLAN_EN
WLAN_EN is used to control the WLAN function of the module. Wi-Fi function will be enabled when
WLAN_EN is at high level.
Table 9: Pin Definition of WLAN_EN
WLAN_EN is the Wi-Fi function enable signal. When wiring, keep it away from sensitive signals such as
radio frequency, analog signal, clock, and DC-DC noise signals.
3.4.3. WLAN_WAKE
WLAN_WAKE is used to wake up the host.
Pin Name
Pin No.
I/O
Description
Comment
WLAN_EN
12
DI
Wi-Fi function enable control
VDDIO power domain.
Active high.
NOTE
