Scheme introduction:
The body temperature is one of the important indicators to show whether the human body is healthy.
The accurate measurement of the body temperature can quickly separate the people who are suspected of being infected, so as to avoid a large-scale outbreak of the epidemic. The typical non-contact measurement method of household electronic thermometer is infrared temperature measurement. Since the principle of infrared radiation was discovered, infrared technology has been widely used in temperature measurement. The infrared thermometer has the characteristics of wide temperature measurement range, fast response speed and high sensitivity. The infrared ear temperature gun, infrared forehead thermometer and infrared screening instrument are all non-contact thermometers.
Temperature measuring principle of infrared thermometer scheme
When an object is above jue to zero, because of the movement of charged particles inside it, it radiates energy outwards in the form of electromagnetic waves of different wavelengths.
The wavelengths involve ultraviolet, visible and infrared light regions, but are mainly 0.76~3 μ Near infrared of m, 3~6 μ M Mid infrared, 6~15 μ M Far infrared region. The size and wavelength distribution of infrared radiation energy of an object are closely related to its surface temperature. Therefore, by measuring the infrared energy radiated by an object itself, its surface temperature can be accurately measured, which is the objective basis for infrared radiation temperature measurement.
Introduction to Scheme Chip of Infrared Thermometer
1. Overview
ZHW3548 is an 8-bit CMOS single chip MCU with 8K * 16bits one-time programmable OTP ROM (it can only be used for 4K and 4K twice), 256 * 8bits data memory SRAM, a 24 bit ADC with 1 channel full differential analog signal input, low noise amplifier and 4 * 16 LCD driver, UART serial port communication module, low voltage burning control circuit, and Zui low 2.5V self burning. Its characteristics are as follows:
8-bit MCU, 39 single word instructions, 8-level storage stack
Ultra low power consumption: 500 in normal mode μ A (500KHz, 3.3V), current is less than 2 in sleep mode μ A
8K * 16bits OTP ROM (can be used for 4K and 4K twice)
256*8bits SRAM
UART serial communication
Built in 16MHz oscillator
External 32768Hz crystal oscillator (RTC), 4MHz~16MHz crystal oscillator
One full differential analog input 24 bit ADC, internally integrated programmable gain amplifier, ADC output rate 30Hz~3.9KHz
Built in charge pump, built-in voltage regulator for sensor and modulator, built-in temperature sensor
8-bit programmable prescaler 8-bit timing counter
Watchdog timer WDT
14 bit bidirectional I/O port, 1 channel buzzer output, PT27 or PT23 output can be selected, default PT27 port output
4 * 16 LCD drive
Power on reset, low-voltage reset, low-voltage detection
2.external interrupts
Built in low-voltage burning control circuit, ZUI low 2.5V can self burn
Packaging form: LQFP48
Performance parameter:
Industry classification: medical electronics
Delivery form: PCBA
Performance parameter: function: temperature measurement
Application scenario: household, commercial