nanopi_max86150_ecg_ppg

Before starting building code, wiringPi must be downloaded.

apt-get install wiringpi

Or directly built from source code:

git clone https://github.com/friendlyarm/WiringNP
cd WiringNP/
chmod 755 build
./build

Note, that special flags must be set while calling gcc

-lwiringPi -lpthread

By default I2C speed is around 90 KBaud, while MAX86150 support up to 400KBaud. Unfortunately, I couldn't reach such speed. My maximum is 250KBaud, but board didn't work well on such speeds, so I stick to 210KBaud. To make it happen, device tree must be decompiled, edited, recompiled and replaced

Decompile:

dtc -I dtb -O dts /boot/sun8i-h3-nanopi-neo-air.dtb -o /tmp/sun8i-h3-nanopi-neo-air.dts

Edit:

Few lines must be found with text redactor:

            i2c0 {
                pins = "PA11\OPA12";
                function = "i2c0";
                linux,phandle = <0x2c>;
                phandle = <0x2c>;
            };

        i2c@01c2ac00 {
            compatible = "allwinner,sun6i-a31-i2c";
            ...
        };

and next parameter must be added to both places (I added it after phandle):

clock-frequency = <400000>;

Important note: even though we added 400000, it doesn't mean we will have 400KB. As I said, with this value I only received 210KB, while 760000 gave me 250KB.

Compile device-tree, replace it, reboot:

dtc -I dtb -O dts /tmp/sun8i-h3-nanopi-neo-air.dts -o /tmp/sun8i-h3-nanopi-neo-air.dtb
cp /tmp/sun8i-h3-nanopi-neo-air.dtb /boot/sun8i-h3-nanopi-neo-air.dtb

After reboot try to find device with i2cdetect:

root@NanoPi-NEO-Air:/home/pi/nanopi_max86150_ecg_ppg# i2cdetect -y 0 
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5e -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

Device 5e is MAX86150.