Wi-Fi&Bluetooth Module Series
FC909A_Hardware_Design 28 / 49
The voltage range of the Bluetooth UART of FC909A is determined by VDDIO. It is necessary to pay
attention to whether the voltage range of the host and FC909A Bluetooth UART is consistent. If
necessary, voltage-level translator shall be adopted.
The following figure shows a reference design for UART connection between FC909A and the host.
BT_CTS
BT_RTS
BT_RXD
BT_TXD
FC909A
UART_RXD
UART_TXD
UART_CTS
UART_RTS
Host
Figure 7: Reference Design for UART Connection
When paired with Quectel's LTE modules, it may be their own CTS connected to CTS and RTS
connected to RTS. This depends on the input and output directions, so in principle, when connected, the
input shall corresponds to the output.
3.5.2. BT_EN
BT_EN is used to control the Bluetooth function of FC909A. Bluetooth function will be enabled when
BT_EN is at high level.
Table 14: Pin Definition of BT_EN
Pin Name
Pin No.
I/O
Description
Comment
BT_EN
34
DI
Bluetooth enable control
Active high.
If unused, please pull it down.
VDDIO power domain.
NOTE