Bluegiga Technologies Oy
Page 15 of 18
5 Interfaces
5.1 Powering the evaluation board
The evaluation kit can be powered in three ways:
1. Connect 5 V DC to J2. 100 – 240 V AC to 5 V DC switching power supply is delivered with the
evaluation kit.
2. Connect 5 V DC to the header J3 or 3,3 V DC to at least one of the 24 pin header’s 3V3 pins
3. Connect 5 V DC through the USB interface and set SW13 for bus-powered mode
5.2 USB
WT41 can be configured to operate in a bus-powered or in a self powered mode. See the datasheet of WT41
and the HW design guide of WT41 for more detailed information. In the evaluation board, the switch SW13 is
used to define the hardware configuration. For the related software configuration use PSTool software to set
the required PSKEYs. Relevant PSKEYs are:
PSKEY name Description
PSKEY_HOST_INTERFACE Set to 2 to enable HCI-USB mode immediately at
boot (otherwise refer to BOOT 3 command of iWrap
firmware)
PSKEY_HOST_INTERFACE_PIO_USB Set to 2 – 7 to force the USB interface when that PIO
line is pulled high, overriding
PSKEY_HOST_INTERFACE
PSKEY_USB_MAX_POWER Maximum current drawn by the device in units of 2
mA. This must be set for WT41 always since WT41
peak currents are over 100 mA
PSKEY_USB_PIO_VBUS A values between 2 and 7 indicate the PIO line to be
used to monitor USB VBUS. If key is not present
then firmware assumes that USB VBUS is always
present. Keep not present for bus-powered device.
In the evaluation kit USB detection is connected to
PIO6.
PSKEY_USB_ATTRIBUTE_POWER Change to zero for bus-powered device
PSKEY_USB_PIO_PULLUP A values between 2 and 7 indicate the PIO line to be
used to enable and disable USB D+/D- pull-up
resistor. Setting to 16 enables the internal pull-up to
be used for bus-powered device. In the evaluation
PIO2 is dedicated for USB pull-up resistor.
Table 1: USB Configuration Settings
NOTE: The evaluation kit is only for evaluation purposes for the module and is not guaranteed to be 100%
USB compliant. For example the power on LED is always on when VDD is present and thus the kit will not
meet the USB regulations for the suspend current. See the HW design guide for USB design considerations.
