Data Sheet

Bluegiga – A Silicon Labs Company 10
Pin-out description
This section contains a description of the BT121 pin-out. Each pin may have one or more functions which are
all listed in tables. The pin-out is shown in Figure 4 below.
Figure 4 BT121 pin-out (top view)
3.1 Power, ground, reset, RF and boot loader pins
Power supply, ground, reset signal, RF antenna input/output and boot loader related pins are listed in Table 1
below.
Pin / Pad
Function
Description
30,34
VDD
Module power supply input pins.
1, 2, 3, 13, 21,
31, 32, 33, 41
GND
Ground pin. These are all connected together internally but they should all be individually
connected directly to a solid ground plane with vias in close proximity to the pins. This requirement
concerns especially the antenna connections.
22,40
RESET
Module reset signal pins. Pulling RESET low will reset the internal processor of the module. These
connections have an internal pull-up and can be left floating if not needed.
23,35
BOOT0
Boot mode pin of the microcontroller internal boot loader. This connection has an internal pull-down
and should be left floating or pulled low in normal operation.
If the Bluegiga DFU is overwritten or disabled, pulling BOOT0 high at reset will allow DFU to be
rewritten through the UART (serial port interface).
Table 1 Power, ground, reset, RF and boot loader pins