User's Manual

2-3. DC Characteristics for Host I/O
Symbol Parameter Condition Min Typ Max Units
V
IL
Input low voltage (V
DDIO
V
DDIO
_
SD
) 1.8V Logic 0.6 V
V
IH
Input high voltage (V
DDIO
V
DDIO
_
SD
) 1.8V Logic 1.1 V
V
OL
(
~100uA Load
)
Output low voltage (V
DDIO
V
DDIO
_
SD
) 1.8V Logic 0.2 V
V
OH(~100uA Load)
Output high voltage (V
DDIO
V
)
1.8V Logic V
IO
- 0.2V V
V
IL
Input low voltage (V
DDIO
V
DDIO
_
SD
) 3.3V Logic 0.8 V
V
IH
Input high voltage (V
DDIO
V
DDIO
_
SD
) 3.3V Logic 2.0 V
V
OL
(
~100uA Load
)
Output low voltage (V
DDIO
V
DDIO
_
SD
) 3.3V Logic 0.2 V
V
OH
(
~100uA Load
)
Output high voltage (V
DDIO
3.3V Logic V
IO
- 0.2V V
2-4. BT/FM Host Interface
The AW-NH930 is the optimal solution for any voice or data application that requires the Bluetooth SIG
standard Host Controller Interface (HCI) using a high-speed UART. The FM subsystem and the
Bluetooth subsystem share the same high-speed UART
2-4-1. UART Interface
The UART physical interface is a standard, 4-wire interface (RX, TX, RTS, CTS ) with adjustable baud
rates from 9600 bps to 4.0 Mbps. The interface defaults to a baud rate of 115.2 Kbps coming out of reset.
The desired high-speed baud rate may be selected via a vendor-specific UART HCI command. The AW-
NH930 has a 480-byte receive FIFO and a 480-byte transmits FIFO to support EDR. The interface
supports the Bluetooth 2.1 UART HCI (H4) specification. The default baud rate for H4 is 115.2 k baud.
In order to support both high and low baud rates efficiently, the UART clock can be selected as either 24
or 48 MHz. Generally, the higher speed clock is needed for baud rates over 3 M baud, however a lower
speed clock may be used to achieve a more accurate baud rate under 3 M baud.
The legacy method of programming the high-speed baud rate of the AW-NH930 UART using DHBR and
DLBR values is also supported for backward compatibility with previous-generation Bluetooth devices.
Normally, the UART baud rate is set by a configuration record downloaded after 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-NH930 UART operates correctly with the host UART, provided the combined baud rate error of
the two devices is within ±5%
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