2_3

2_3

The work of this week is testing the LCD screen and ensures the LCD screen can be used in heart rate and SPo2 monitoring system.

Hardware requirements:

1.     LCD screen

Software requirements:

1.     Arduino 1.8-3

Connection requirement

LCD screen	Arduino Uno R3
SCL	SCL
SDA	SDA
GND	GND
VCC	5V

First of all, connect the LCD screen to Arduino Uno as connection requirement, then power on the Arduino Uno R3 board. The LCD screen will light. Next, download the test program “Hello world” and compile it. The LCD screen can be displayed Hello world. It can be seen in figure 1.

 

Figure 1: the results from the LCD screen

If the LCD screen displays the “Hello world”, which can prove the LCD screen can be used. Therefore, the next step to add the header file Wire.h, LiquidCrystal_I2C.h and Set the LCD address to 0x27 for a 16 chars and 2 line display named that LiquidCrystal_I2C LCD (0x27, 16, 2); Finally, add the output to LCD serial port. The final result is that the heart rate value and the blood oxygen value are displayed together on the LCD screen.

Conclusion

Since the LCD screen is instantaneous output data. On the one hand, there is a delay in the optical sensor; on the other hand, it is to collect 4 seconds of data and then output. Causes an error on the LCD screen display, such as the heart rate is -999 and the blood oxygen is -999. I purchased an optical sensor that can output in time to solve this problem. It will be described in the next blog.