Wireless smoke alarm all-round design and large delivery: master + wireless + sensing...

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Major fire accidents have occurred, causing significant losses to both life and property. As a result, automatic fire protection systems have gained widespread attention from the government, society, and various industries. The demand for advanced automatic fire alarm and suppression systems has continuously increased, driving innovation and development in this field.

This article presents a comprehensive solution for an automatic fire alarm and suppression system. The system diagram is as follows:

The image above illustrates the fire alarm and automatic fire extinguishing system provided by Shiqiang. This system utilizes flue gas sensors and temperature sensors in conjunction with a microelectronic judgment circuit to trigger alarms or electromagnetic relays for early warning. Among these components, Shiqiang’s SI7055 temperature sensor plays a key role. It sends collected data to Renesas MCU R5F117BCGFP, which then transmits the information via Silicon Labs' SI4438 wireless transceiver chip to the main control unit through CAN bus. The main control unit manages water spray operations and also provides alarm display functionality.

For optimal performance, the system requires strong wall-penetrating radio signals with high link budget and receiving sensitivity better than -110dBm. Wireless smoke detectors typically use chips operating in frequency bands below 1GHz, such as 315MHz, 433MHz, 868MHz, and 915MHz, which are ideal for reliable communication in such environments.

Several Shiqiang-authorized components are used in this system. Their features and advantages are detailed below. You can also find the latest product information on the Shiqiang component e-commerce app.

Shiqiang-authorized Renesas MCU R5F117BCGFP:

The R5F117BCGFP integrates multiple analog functions, including op amps, comparators, and ADCs. It features up to four operational amplifiers, enabling efficient signal processing with minimal external components. Its fast wake-up time of only 13μs makes it suitable for real-time applications. With a supply voltage range of 1.6V to 3.6V, it supports low-power operation, reducing overall power consumption significantly.

The chip offers four operating modes—Operating, Halt, Stop, and Snooze—to optimize power usage. At 1MHz, it consumes less than 150μA, and at 15kHz, it drops to just 6μA. In Halt mode, power consumption is under 2μA, making it ideal for battery-powered devices. The R5F117BCGFP also includes a built-in voltage monitor that alerts users when power levels are low, preventing potential failures.

Shiqiang-authorized Silicon Labs EFM32WG230F256:

The EFM32WG230F256 is a high-performance 32-bit processor based on the Cortex-M4 core, capable of running at up to 48MHz. It features a floating-point unit, optional flash memory (256KB/128KB/64KB), 32KB RAM, 56 IO ports, and 12 DMA channels. It also includes hardware AES encryption, dual RTC options, and multiple power-saving modes, such as 20nA in shutdown mode and 0.4μA in RTC sleep mode.

Silicon Labs Si44xx Wireless Transceiver Chip:

Two versions of the Si44xx series are available: Si4438 and Si4463. The Si4438 operates between 425MHz and 525MHz, while the Si4463 covers a broader range, including 315MHz, 868MHz, and 915MHz. The Si4463 offers excellent performance, with a receiving sensitivity of -129dBm and transmit power up to 20dBm. Its low power consumption—only 30nA in shutdown and 40nA in standby—makes it ideal for long-lasting wireless systems.

Silicon Labs SI7055 Temperature Sensor:

The SI7055 is a cost-effective, high-accuracy digital temperature sensor with ±0.5°C accuracy over a wide operating range (-40°C to +125°C). It operates at 1.9V to 3.6V and features 14-bit resolution with an average power consumption of just 195nA at 1Hz sampling rate. It is factory-calibrated and available in a compact 3x3mm DFN package, making it suitable for space-constrained designs. The sensor also meets AEC-Q100 automotive standards, ensuring reliability in demanding environments.