BLE SoC Selection Criteria for IoT Device Design: Key Considerations

This blog is the sequel of the blog “Bluetooth Technology”. In the previous blog we discussed in detail the basics of Bluetooth, how communication takes place, and how Bluetooth is classified. In this blog we describe the BLE SoC selection criteria for IoT device design, covering the full range of parameters and options that engineers must evaluate when building a Bluetooth Low Energy (BLE) based IoT device. Understanding these BLE SoC selection criteria for IoT device design is essential for delivering reliable, power-efficient wireless products across industries from healthcare to industrial automation.

BLE SoC Selection Criteria for IoT Device Design: Overview

Today we find numerous BLE-enabled IoT devices emerging in the market with typical applications such as wrist wearables in healthcare, beacons and tags in retail, and many more in home automation, industrial, and automotive segments. Applying the right BLE SoC selection criteria for IoT device design from the outset prevents costly redesigns and ensures the product meets power, range, and integration requirements. In all these domain applications the most important design criteria are as follows:

1. Cost
2. Form factor
3. Range
4. Sensor integration
5. User interface
6. Power supply

In the following sections we will discuss in detail what is important for selecting a BLE SoC when building BLE based IoT devices, and the multiple options available to choose from.

BLE Wearable Device Design: Key Parameters

BLE wearable device design imposes particularly demanding constraints because the product must be small, lightweight, long-lasting on battery, and capable of reading data from body sensors in real time. Fitness trackers and health monitors — both classic ble wearable device design targets — illustrate the challenge: they must continuously acquire data from MEMS accelerometers, gyroscopes, and heart-rate sensors while keeping average current consumption in the microamp range. Good ble wearable device design therefore starts with careful SoC selection, because the SoC simultaneously determines processing power, BLE link quality, peripheral set, package size, and power draw. The BLE SoC selection criteria for IoT device design framework below maps directly onto these wearable requirements.

BLE SoC

A BLE SoC is an integrated chip that includes both the microcontroller and BLE transceiver. They are also named wireless microcontrollers. The microcontroller part includes the core, flash memory, RAM, and peripherals such as GPIO, I2C, SPI, UART, timers, and ADC. The BLE part includes an RF transceiver compatible with BLE specifications (typically v4.0, v4.1, or v4.2). In addition to BLE, some SoCs also support IEEE 802.15.4, the standard underpinning ZigBee, MiWi, and Thread, expanding the scope of custom wireless IoT solutions the device can address.

The following are the detailed BLE SoC selection criteria for IoT device design:

1. Core: Most BLE SoCs in the market are powered by an ARM Cortex core such as Cortex-M0+ or Cortex-M3. A few SoCs carry an 8051 core. The choice of core depends on the application: M3 suits high-computation, real-time applications while M0+ balances cost and performance for simpler BLE microcontroller applications.
2. Memory: All SoCs carry on-chip SRAM and Flash. Flash size is the primary concern: it must accommodate the application, OTA update code, and BLE stack simultaneously. Selecting an SoC with sufficient flash memory is strongly advisable. If the application code and BLE stack fill the available flash, there is no room for OTA support, and the only recourse is external EEPROM — adding cost to the BoM. This is a critical BLE SoC selection criteria for IoT device design because Custom BLE firmware for IoT wearables typically includes OTA capability to push firmware updates in the field without physical access to the device.
3. TX/RX Power: For any BLE wireless application, range is an important factor. Transceiver power, specified in dBm, is the primary range determinant. The range also depends on the antenna used; proper antenna selection and RF layout design are discussed in our companion article on BLE PCB antenna impedance matching design.
4. Power: Power consumption is the most important of all BLE SoC selection criteria for IoT device design, especially for ble wearable device design running on coin cells or small LiPo batteries. Both MCU and RF transceiver power must be considered.
   1. Option for controlling TX/RX power: Reducing TX/RX power lowers consumption but also reduces range — a trade-off that must be balanced per application.
   2. Option for multiple low-power operating modes: Low-power modes disable peripherals and clocks that are not needed, dramatically reducing standby current. Selecting the appropriate mode for each phase of operation is key to achieving long battery life in ble wearable device design.
5. Peripherals: The BLE SoC core includes multiple peripherals such as I2C, SPI, I2S, GPIOs, timers, UART, and ADCs. The SoC under consideration should support the full set of external interfaces required by sensors, actuators, displays, and audio/visual indicators. A fitness tracker, for example, acquires data from MEMS sensors (accelerometer, gyroscope, magnetometer) via I2C and SPI, while analog sensor front-ends connect through high-resolution ADCs. Buzzers driven by PWM timer outputs require no extra components — all handled inside the SoC.

6. Package: BLE SoCs are available in SMD packages such as QFN and BGA. QFN is most common. Both packages require machine soldering, which adds assembly cost and must be factored into the BLE SoC selection criteria for IoT device design early in the programme.
7. Operating conditions: The operating grade (commercial, industrial, automotive, medical) is critical. A commercial-grade SoC is not suitable for automotive-grade applications and vice versa. This criterion is especially important when Custom BLE firmware for IoT wearables is targeted at medical or industrial markets with extended temperature or certification requirements.
8. Availability of evaluation platforms, source code, and software stacks should be verified; these resources directly accelerate Custom BLE firmware for IoT wearables development and reduce time to market.

Custom BLE Firmware for IoT Wearables: Development Considerations

Selecting the right SoC is only part of the equation. Custom BLE firmware for IoT wearables must be architected to make the most of the hardware. The firmware stack typically includes a BLE host stack (managing GAP/GATT roles), application-layer logic for sensor acquisition, a power management state machine that leverages low-power modes, and an OTA bootloader for field updates. Flash sizing must account for all four components plus a staging area for the OTA image. Engineers developing Custom BLE firmware for IoT wearables should also plan for security: encrypted OTA update channels, bonding key storage, and, where relevant, transport-layer security for cloud data uploads. Embien provides ST Micro Device Expertise and supports multiple BLE SoC families, delivering Custom BLE firmware for IoT wearables from early prototyping through production release.

BLE Microcontroller Applications: SoC Options from Leading Vendors

The following are popular BLE SoC part numbers available in the market for a wide range of BLE microcontroller applications:

• Texas Instruments: CC2540, CC2541, CC2640, CC2650
• NXP Semiconductors: KW30Z/31Z, KW40Z/41Z
• Renesas: RL78/G1D
• Nordic Semiconductor: nRF52840, nRF52832, nRF51822, nRF51824, nRF51422
• STMicroelectronics: BlueNRG-1

Custom Wireless IoT Solutions with BLE Modules

For devices requiring only BLE connectivity, pre-certified BLE modules offer a faster path to market. These modules integrate the SoC with a built-in chip or PCB antenna, expose all necessary peripherals through expansion connectors, and accept power through the same connector set. Communication with the host processor uses I2C, SPI, or UART. The key advantage of BLE modules is that they are fully tested and compliance certified — making them a strong choice for custom wireless IoT solutions where RF certification cost and time are major programme constraints. This approach can significantly simplify Custom BLE firmware for IoT wearables projects, because the radio layer is already qualified by the module vendor.

About Embien

Embien Technologies is a leading provider of embedded design services for the Semiconductor, Industrial, Consumer, and Healthcare segments. Embien applies rigorous BLE SoC selection criteria for IoT device design across all engagements, covering ble wearable device design, Custom BLE firmware for IoT wearables, RF layout, and cloud integration. Embien has successfully executed many IoT projects including healthcare wearables, gateways, and data analytics platforms. Embien also offers wearable design collections complete with electronics, firmware, and cloud connectivity to significantly reduce product development costs and time-to-market.