Kaga Fei unveils 8.55 mm Bluetooth module

On a circuit board, Kaga Fei's new radio module takes up barely more space than a fingernail: the Japanese company has unveiled the 8.55 mm × 3.25 mm ES4L15MA1, which is 1 mm thick. An antenna is already integrated into the circuit board, along with a small microcontroller. It still requires a board onto which the module can be soldered.

The ES4L15MA1 can communicate either over Bluetooth 6.0 Low Energy (LE), a Bluetooth variant designed for low power consumption, or in the 2.4 GHz band. It supports Matter, Thread and Zigbee for smart-home systems. It also supports Bluetooth Mesh, Networked Lighting Control for connected lighting, and Periodic Advertising with Responses, a method for timed wireless responses.

The data rate is limited to two megabits per second. Up to eight devices can be connected simultaneously. The speed is sufficient for querying devices on networks, for example when working with connected sensors or for status logs. At its core is Nordic Semiconductor's nRF54L15 microcontroller, with a Cortex-M33 core running at 128 MHz and an additional RISC-V coprocessor.

The main practical difference from the similarly small ES4L15BA1 lies in the software: the ES4L15MA1 comes with firmware already preinstalled. Developers do not have to assemble the complete software stack themselves, which could make it easier for makers to get started. Kaga Fei offers an evaluation board for this purpose; the previous module without preinstalled firmware costs just under 14 euros individually from Mouser, excluding VAT.

So what does this change in practice? Sensors, lighting and other small smart-home devices could be built with less space required on the circuit board and less integration work. The next verifiable step will not come until January 2027, when Kaga Fei plans to ship test samples; the start of mass production has been announced for February. Until then, this is an unveiled module, not a product already broadly available on the market.