“Building automation systems have multiple functions that can improve the comfort and safety of workers in industrial and commercial environments. Through innovative microcontroller (MCU) technology, these functions can become more intelligent and economical. In order to design a better building automation solution, appropriate components should be selected to realize the different functions of these applications. The use of a dedicated MCU enables the system to detect, sense and control a variety of parameters in the working environment, thereby increasing the flexibility of design.
Author: Texas Instruments
Building automation systems have multiple functions that can improve the comfort and safety of workers in industrial and commercial environments. Through innovative microcontroller (MCU) technology, these functions can become more intelligent and economical. In order to design a better building automation solution, appropriate components should be selected to realize the different functions of these applications. The use of a dedicated MCU enables the system to detect, sense and control a variety of parameters in the working environment, thereby increasing the flexibility of design.
Precise detection and sensing of movement: PIR solutions
Passive infrared or pyroelectric infrared (PIR) sensors are commonly used in security systems and motion detection applications. You can choose a variety of different technologies to integrate the PIR solution into the motion detection system to detect whether there are “hot” objects or people passing by in front of the sensor. PIR needs low power consumption, small components, low noise, and high-precision sensing under any circumstances to accurately detect the infrared radiation of objects or people.
Motion sensors usually use analog band-pass filters, although the design of such filters is more complicated. Discrete analog methods are susceptible to noise (via capacitors) and may produce low-frequency noise that affects motion detection. In contrast, the intelligent analog combination integrated in microcontrollers such as MSP430FR2355 can provide the entire signal chain of the PIR sensor, and can adjust the sensitivity and detection range through software configuration, provide a digital feedback loop, and optimize the low power consumption of the sensor performance. The PIR sensor based on MSP430 MCU has many advantages, as shown in Figure 1.
Figure 1: The advantages of analog PIR & MSP430 signal conditioning technology
Neither digital analog nor digital PIR solutions can easily adapt to varying ranges, target speeds, ambient temperatures, and lighting conditions. TI’s test results show that the PIR motion sensor designed with MSP430 MCU can detect motion from 36 feet (11 meters) away without analog and digital signal processing.
A digital PIR solution with an integrated signal chain is simple to design, but the cost may be higher. MSP430 MCU integrates the signal chain into the MCU and maximizes battery life by using the MCU’s low-power mode to achieve low noise, low power consumption (≅6uA) and high-performance signal chain, and apply it to motion detection . Compared with similar digital PIR solutions, the use of fewer components can make the printed circuit board smaller and the layout simpler, which can save up to 20% of the bill of materials cost.
Motor Control: Camera Motor Module
Automated security applications, including Internet protocols and video conferencing cameras, require automatic control of tilt, focus, and iris. These cameras use electric or manual control modules to pan, tilt and adjust the lens focal length. The motor module is powered by an external power supply unit, and the microcontroller in the unit must communicate with the motor driver to generate the control signals required for full operation.
The motor control design in Figure 2 uses a dedicated MSP430FR2155 MCU and two DRV8428 stepper motor drivers. MSP430 MCU can control a variety of internal motor functions, including:
• Motor speed
• turn around
• Voltage output of DC motor
• Stepper motor position using universal asynchronous receiver/transmitter
• Reduce power consumption when the system is not running
Figure 2: Block diagram of a motor module using MSP430 MCU and DRV8428 motor driver
The two DRV8428 stepper motor drivers achieve focus and tilt control through precise subdivision drivers (1/256 microsteps) and current adjustable functions, which are equivalent to DC motors. Another DRV8837C brushed DC motor driver is used to control the iris, which can protect the system from short circuits, undervoltage and overheating. The solution can provide multiple modes to achieve ultra-smooth and stable motion curves.
High-precision detection, sensing and control through MSP430 MCU can optimize building automation performance and improve efficiency. You can read our application report in depth, and then use our LaunchPad development kit for evaluation.