Introducing the Adafruit Bluefruit LE SPI Friend

by Kevin Townsend

published July 07, 2015, last updated March 08, 2024

posted in Adafruit Products

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Beginner

Project guide

UART Service

Base UUID: 6E400001-B5A3-F393-E0A9-E50E24DCCA9E

This service simulates a basic UART connection over two lines, TXD and RXD.

It is based on a proprietary UART service specification by Nordic Semiconductors. Data sent to and from this service can be viewed using the nRFUART apps from Nordic Semiconductors for Android and iOS.

This service is available on every Bluefruit LE module and is automatically started during the power-up sequence.

Characteristics

Nordic’s UART Service includes the following characteristics:

Name
TX
RX

Mandatory
Yes
Yes

UUID
0x0002
0x0003

Type
U8[20]
U8[20]

R

X

W
X

N

X

R = Read; W = Write; N = Notify; I = Indicate

Characteristic names are assigned from the point of view of the Central device

TX (0x0002)

This characteristic is used to send data back to the sensor node, and can be written to by the connected Central device (the mobile phone, tablet, etc.).

RX (0x0003)

This characteristic is used to send data out to the connected Central device. Notify can be enabled by the connected device so that an alert is raised every time the TX channel is updated.

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