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DSH_BT024-00200_1v4 © Ezurio Ltd 2006
7
(GPIO9)
V
OH
min=2.8V
slave mode.
Shared with GPIO_9
3.3.2.5
Miscellaneous
Function
Signal Name
Pin No
I/O
Signal level
Comments
Reserved
USB D-
3
I
V
IL
max =0.3vdd_usb
V
IH
min =0.7vdd_usb
Normally
inactive.
Pull to GND through
10K
Reserved
USB D+
2
I
V
IL
max =0.3vdd_usb
V
IH
min =0.7vdd_usb
Normally
inactive.
Pull to GND through
10K
Reset
RESET
5
I
Threshold 2.6V
Active LOW
Terminology:
USB Signal Levels. vdd_usb refers to the internal voltage generated by the LDO regulator on the module, which
is typically 3.1V. Hence 0.3vdd_usb and 0.7vdd_usb correspond to 0.9 V to 2.1V. If Vcc falls below the
recommended minimum of 3.3V, USB operation cannot be guaranteed.
The USB lines cannot be accessed when using AT firmware.
4.
I/O Characteristics
4.1
Power Consumption
The current drain from the Vcc power input line is dependent on various factors. The three most significant factors
are the voltage level at Vcc, UART Baudrate and the operating mode.
The hardware specification for the Module allows for a voltage range of 3.3 to 7.0 at Vcc. Tests have shown that
where power drain is an issue, it is best to keep Vcc at the lower end of the range.
The UART Baudrate has a bearing on power drain because as is normal for digital electronics, the power
requirements increase linearly with increasing clocking frequencies. Hence higher baudrates result in a higher
current drain.
Finally with regards to operating mode the significant modes are; idle, waiting for a connection, inquiring,
initiating a connection, sniff and connected. With connected mode, it is also relevant to differentiate between no
data being transferred and when data is being transferred at the maximum rate possible. The AT command Set
document describes how to configure the Module for optimal power performance.