Bluefruit LE Friend - Bluetooth Low Energy 4.0 - nRF51822

USB-to-BLE bridge based on the nRF51822, presenting as a USB serial device to a computer and communicating with BLE 4.0 peripherals over UART. Allows a PC or Mac to interact with BLE-enabled phones and tablets.

Logical pinout · physical placement not verified

VINpower header
Power supply input, regulated to 3.3V on the breakout
Type · PowerVoltage · 3.3V to 16V input
GNDpower header
Common ground for power and logic
Type · GroundVoltage · 0V
TXOUART header
UART transmit out of Bluefruit LE to MCU
Type · UARTVoltage · 3.3V logic
RXIUART header
UART receive into Bluefruit LE from MCU
Type · UARTVoltage · 3V to 5V logic accepted via level shifter
CTSUART header
Clear-to-send input; pull low to allow data out on TXO
Type · UARTVoltage · 3V to 5V logic accepted via level shifter
RTSUART header
Ready-to-send output from module
Type · UARTVoltage · 3.3V logic
MODcontrol pads
Command/data mode select, high = command mode, low = UART/data mode
Type · ControlVoltage · 3V to 5V logic accepted via level shifter
DFUcontrol pads
Force DFU mode on power-up or factory reset when held low after power-up
Type · Control
SWCtest/advanced pads
SWD clock for advanced debugging
Type · SignalVoltage · 3.3V logic
SWDtest/advanced pads
SWD data for advanced debugging
Type · SignalVoltage · 3.3V logic
3Vopower/test pad
Output from onboard 3V regulator
Type · PowerVoltage · regulated 3V, up to 250mA
FCRcontrol pad
Factory reset pad, tie to ground while powering up for reset
Type · Control

Pin	Position	Type	Function	Voltage
VIN	power header	Power	Power supply input, regulated to 3.3V on the breakout	3.3V to 16V input
GND	power header	Ground	Common ground for power and logic	0V
TXO	UART header	UART	UART transmit out of Bluefruit LE to MCU	3.3V logic
RXI	UART header	UART	UART receive into Bluefruit LE from MCU	3V to 5V logic accepted via level shifter
CTS	UART header	UART	Clear-to-send input; pull low to allow data out on TXO	3V to 5V logic accepted via level shifter
RTS	UART header	UART	Ready-to-send output from module	3.3V logic
MOD	control pads	Control	Command/data mode select, high = command mode, low = UART/data mode	3V to 5V logic accepted via level shifter
DFU	control pads	Control	Force DFU mode on power-up or factory reset when held low after power-up
SWC	test/advanced pads	Signal	SWD clock for advanced debugging	3.3V logic
SWD	test/advanced pads	Signal	SWD data for advanced debugging	3.3V logic
3Vo	power/test pad	Power	Output from onboard 3V regulator	regulated 3V, up to 250mA
FCR	control pad	Control	Factory reset pad, tie to ground while powering up for reset

Logical pinout · physical placement not verified

Pin details

12 connections

VIN
Power supply input, regulated to 3.3V on the breakout
PowerVoltage · 3.3V to 16V input
power header
GND
Common ground for power and logic
GroundVoltage · 0V
power header
TXO
UART transmit out of Bluefruit LE to MCU
UARTVoltage · 3.3V logic
UART header
RXI
UART receive into Bluefruit LE from MCU
UARTVoltage · 3V to 5V logic accepted via level shifter
UART header
CTS
Clear-to-send input; pull low to allow data out on TXO
UARTVoltage · 3V to 5V logic accepted via level shifter
UART header
RTS
Ready-to-send output from module
UARTVoltage · 3.3V logic
UART header
MOD
Command/data mode select, high = command mode, low = UART/data mode
ControlVoltage · 3V to 5V logic accepted via level shifter
control pads
DFU
Force DFU mode on power-up or factory reset when held low after power-up
Control
control pads
SWC
SWD clock for advanced debugging
SignalVoltage · 3.3V logic
test/advanced pads
SWD
SWD data for advanced debugging
SignalVoltage · 3.3V logic
test/advanced pads
3Vo
Output from onboard 3V regulator
PowerVoltage · regulated 3V, up to 250mA
power/test pad
FCR
Factory reset pad, tie to ground while powering up for reset
Control
control pad

Start wiring

UART · SPI · 3.3 V · 5 V · Breakout

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Module pins: VIN, GND. Schematik maps them to your board in the app.

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