OBS421 – Stand-alone dual-mode Bluetooth module series


16 x 36 x 2.6 mm

Stand-alone dual-mode Bluetooth module series


  • Bluetooth v4.0 with Bluetooth low energy and Classic Bluetooth (Bluetooth Smart Ready)
  • Embedded stack (SPP, DUN, PAN, GATT)
  • u‑blox Low Energy Serial Port Service
  • High throughput of 1.3 Mbps
  • Advanced multipoint capability with 7 slaves
  • Apple iOS and Google Android connectivity
  • Cortex M3 MCU for customer developed applications

 Product description

The powerful stand-alone Bluetooth module OBS421 is a dual-mode (Bluetooth Smart Ready) module complete with embedded Bluetooth stack and serial port application. The OBS421 features a UART interface for transparent serial data transmissions. It can be used as a Bluetooth Smart Ready client for any host and it can access any Bluetooth Smart device that implements services based on the Generic Attribute Profile(GATT), such as a low energy battery service or an automation I/O service. The OBS421 can also be used in applications where a smart-phone, tablet or laptop is to connect to a serial device such as a Programmable Logic Controller (PLC).

Customers may embed their own applications, eliminating the need of an external application processor, thus saving considerably on the bill of material and PCB space. The middleware with easy-to-use interfaces speeds up and simplifies application development. Customer developed applications can make use of the additional module interfaces, such as GPIO, SPI, I2C, JTAG, and UART / USART and analog inputs. The module is fully Bluetooth qualified and provides modular radio type approvals for the US, Europe, Japan and Canada (FCC, R&TTE, MIC, IC). The OBS421 is also compliant with EMC, Safety and Medical standards. The robust module is easily configured via AT commands as well as cover a range of 300 meters, throughput up to 1.3 Mbps and operating temperatures of –30°C to +85°C.


v4.0 (Bluetooth low energy and Classic Bluetooth)
250 m, internal antenna
300 m, external antenna
Output power:
11 dBm, internal antenna
13 dBm, external antenna
1.3 Mbps (Classic Bluetooth)
72 MHz, ARM 32-bit Cortex M3 processor
with 64 kB RAM and 384 kB flash

Software features

Embedded software:
u-blox Bluetooth stack
Serial port application
Bluetooth profiles & services:
u-blox Low Energy Serial Port Service
Generic Attribute Profile (GATT)
Serial Port Profile (SPP)
Dial-up networking Profile (DUN GW,
Personal Area Networking Profile (PAN)
roles: PANU & NAP
Profile roles:
Central Role, Peripheral Role
Max. number of slaves:
7 Classic Bluetooth only
3 Classic Bluetooth & Bluetooth low energy
Configuration tools:
AT commands via Bluetooth or serial port
Serial Port Toolbox (Windows-based SW)
Low Emission Mode®:
Prevent disrupting other 2.4GHz radios
Wireless Multidrop™:
For simultaneous connections to Bluetooth
low energy and Classic Bluetooth devices
Extended Data Mode™:
Individually controlled multipoint data
Quality of Service (QoS)
Repeater functionality:
Extended range
Simple Pairing
Android connectivity:
SPP/PAN Classic Bluetooth and Bluetooth
low energy connections with Android
devices (Android 4.3 and higher)
iOS connectivity:
Supports Bluetooth low energy
connections with iOS devices
Supports Classic Bluetooth connections
with iOS device
Interfaces- UART Logic level:
RS232/RS422/RS485 : Option via external transceiver
Baud rate: Max 1.5 Mbit/s
Support for non-standard baud rates
Flow control:  CTS/RTS (hardware) or none
GPIO pins: 9 pins / 21 pins
SPI and I2C: 2
USART Logic level: 2
ADC channels:  7
U.fl antenna connector (external antenna version omly)
16.0 x 36.0 x 3.2 mm (internal antenna)
16.0 x 36.0 x 2.6 mm (external antenna)
2 g
Mounting holes, Machine mountable,
Board-to-board connector, Solder land pads

Environmental data, quality & reliability:

Operating temperature:    -30 Deg Celsius …+ 85 Deg Celsius


Electric data

RF Power Supply:       3 to 6V DC

Power consumption: 0.6 mA @ 3 V (min)

44 mA @ 3 V (average Tx).

Certifications and approvals:

Type approvals:
Europe (ETSI R&TTE); US (FCC/CFR 47 part 15
unlicensed modular transmitter approval);
Canada (IC RSS); Japan (MIC – formerly TELEC)
R&TTE Directive 1999/5/EC:
Effective use of frequency spectrum:
EN 300 328
EMC: EN 301 489-1, EN 301 489-17,
EN 61000-6-2
Health and safety:
EN 62479, EN 60950-1, IEC 60950-1
Medical Electrical Equipment:
IEC 60601-1-2
Bluetooth Qualification: v4.0

Product variants


Internal antenna


U.FL antenna connector


Internal antenna, Apple iAP support


U.FL antenna connector, Apple iAP support


Internal antenna, supports customer developed applications


U.FL antenna connector, supports customer developed applications


Product Selection

Source: u-blox




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