Complete Bluetooth Smart serial port module

OLS425 Bluetooth low energy moduleThe OLS425 is a complete Bluetooth low energy (Bluetooth Smart) module with UART logic level interface. The module embeds firmware with the u-blox Low Energy Serial Port Service for replacing serial cables or accessing UART devices using Bluetooth low energy technology. It also offers Apple iOS and Google Android connectivity.

The module has a small form factor and offers solder castellations for visual inspection. Options include an internal antenna version or a version with a connector for external antenna. There is also a wide selection of certified external antennas to choose from. The OLS425 Bluetooth low energy module is easily configured via AT commands.

Additionally, the module is Bluetooth qualified and provides modular radio type approvals for the US, Europe, Japan and Canada (FCC, R&TTE, MIC, IC). The OLS425 is also compliant with EMC, Safety and Medical standards. The operating temperature range is –40°C to +85°C.


  • Bluetooth v4.0 with Bluetooth low energy (Bluetooth Smart)
  • Serial port application firmware for UART serial data
  • u-blox Low Energy Serial Port Service
  • Apple iOS and Google Android support

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See the OLS425 product summary for a visual overview of the Bluetooth and Wi-Fi modules' capabilities.


  • Bluetooth v4.0 (Bluetooth low energy)
  • Range:
    • 50 m, internal antenna
    • 200 m, external antenna
  • Output power:
    • 3 dBm, internal antenna
    • 6 dBm, external antenna
  • Receive sensitive level: –91 dBm
  • Throughput: 26 kbps
  • Embedded software:
    • u-blox Bluetooth stack
    • Serial port application
  • GATT based service:
    • u-blox Low Energy Serial Port Service
  • Profile roles:
    • Peripheral (A Peripheral Role device can only communicate with a Central Role device; for example a dual-mode Bluetooth module)
  • Max. number of slaves: 1
  • Configuration tools:
    • AT commands
    • Serial Port Toolbox (Windows-based SW)
  • Security: Simple Pairing
  • Android connectivity:
    • Supports Bluetooth low energy connections with Android devices (Android 4.3 and higher)
  • iOS connectivity:
    • Supports Bluetooth low energy connections with iOS devices
  • Electrical data:
    • RF power supply 2.0 to 3.6 VDC
    • Power consumption: 0.4 μA @ 2.0V (min.), 10 mA @ 2.0V (average Tx)
  • Interfaces:
    • UART logic level
    • Supported baud rates: 57.6 kbps (max.)
    • Flow control: CTS/RTS (hardware) or none
    • GPIO pins: 11
    • U.fl antenna connector (external antenna version only)
  • Package:
    • Dimensions:
      • 14.8 x 22.3 x 3.2 mm (internal antenna)
      • 14.8 x 22.3 x 2.8 mm (external antenna)
    • Weight: 1.5 g
    • Mounting:
      • Mounting holes
      • Machine mountable
      • Solder edge pads with castellations (visually inspectable)
  • Environmental data, quality & reliability:
    • Operating temperature –40°C to +85°C
    • Storage temperature –40°C to +125°C
    • Humidity RH 5-90% non-condensing
  • 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"Bluetooth Smart" is the same as "Bluetoot low energy", a low power, lower data rate version of Bluetooth originally introduced for the healthcare, fitness, security, and home entertainment industries.


Product Documentation


  • View the Bluetooth low energy demo video that shows the use of the u-blox Low Energy Serial Port Service in an industrial setting with a robot, a computer, an iPhone and the modules OLS426, OBS421, and OLP425.

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