Data Sheet

17
FORM NO.: FR2-015_ A Responsible Department：WBU Expiry Date: Forever
The information contained herein is the exclusive property of AzureWave and shall not be distributed, reproduced, or
disclosed in whole or in part without prior written permission of AzureWave.
SDIO Bus Timing a Parameters (High-Speed Mode)
* min (VIH) = 0.7 × VDDIO and max (VIL) = 0.2 × VDDIO
3.4.2 UART Interface
The AW-NM372SM includes a single UART for Bluetooth. The UART is a standard 4-wire interface
(RX, TX, RTS, and CTS) with adjustable baud rates from 9600 bps to 4.0 Mbps. The interface
features an automatic baud rate detection capability that returns a baud rate selection. Alternatively,
the baud rate may be selected through a vendor-specific UART HCI command.
UART has a 1040-byte receive FIFO and a 1040-byte transmit FIFO to support EDR. Access to the
FIFOs is conducted through the AHB interface through either DMA or the CPU. The UART supports
the Bluetooth 5.1 UART HCI specification: H4, a custom Extended H4, and H5. The default baud
rate is 115.2 Kbaud.
The UART supports the 3-wire H5 UART transport, as described in the Bluetooth specification
(“Three-wire UART Transport Layer”).Compared to H4, the H5 UART transport reduces the number
of signal lines required by eliminating the CTS and RTS signals.
The AW-NM372SM UART can perform XON/XOFF flow control and includes hardware support for
the Serial Line Input Protocol (SLIP). It can also perform wake-on activity. For example, activity on
the RX or CTS inputs can wake the chip from a sleep state.
Normally, the UART baud rate is set by a configuration record downloaded after device reset, or by
automatic baud rate detection, and the host does not need to adjust the baud rate. Support for
changing the baud rate during normal HCI UART operation is included through a vendor-specific
command that allows the host to adjust the contents of the baud rate registers. The AW-NM372SM
UARTs operate correctly with the host UART as long as the combined baud rate error of the two
devices is within ±2%.
UART Interface Signals
PIN No.
Name
Description
Type
40
UART_TXD
Bluetooth UART Serial Output. Serial data output for the HCI
UART Interface
O
41
UART_RXD
Bluetooth UART Series Input. Serial data input for the HCI
UART Interface
I
43
UART_RTS_N
Bluetooth UART Request-to-Send. Active-low
request-to-send signal for the HCI UART interface
O
42
UART_CTS_N
Bluetooth UART Clear-to-Send. Active-low clear-to-send
signal for the HCI UART interface.
I