1. Power supply : 4.5V DC
2. Warm-up mode
Turn the power switch to ON after power-on.
It might take 120 seconds for warm-up. The LCD displays a countdown of 120 seconds and the green LED flashes once each second in the process. It enters the normal mode after warming up.
If the board has not been calibrated, the green and yellow LEDs flash once each second in the process.
3. Normal mode
The green LED flashes once every 40 seconds, and the LCD displays nothing.
4. Low-voltage mode
When the voltage is lower than 3.6V, the buzzer beeps once every 40 seconds if it is under normal mode. Otherwise, the LCD displays a battery icon.
5. Alarm mode
When the CO concentration is detected to exceed 180ppm, the alarm mode is entered.
The buzzer beeps once then stop two second, the red LED flashes once at the same time, and cycles four times. The LCD displays the current CO concentration in the process.
If CO concentration is detected to be lower than 40ppm, the alarm mode is lifted automatically.
6. Test mode
Please press the test button to enter test mode. It simulates the alarm mode in this mode. The green and yellow LED are always on, and the LCD displays 0ppm.
7. Calibration mode
Short the BD connector pins on the board after warm-up. The CO concentration for calibration is 128ppm.
It might take 120 seconds to be calibrated. The green LED keeps flashing, and LCD displays bd2.
If the calibration is successful, the normal mode is entered. Otherwise, the calibration failure mode is entered.
8. Calibration failure mode
If the board has not been calibrated, all of the LEDs light on, and the LCD displays bdE.
