Unused pins on RPi 3B+

Hi

I don’t quite understand on how to read schematic of Grove Pi+ but what are the unused pins on Pi 3B+ that i can use ? I want to connect to sensors that are not from Grove kit.

Thank you

Disclaimer: I don’t know anything about GrovePi - and
plugging wires direct to your RPi can easily burn a single GPIO or the whole board

A BETTER APPROACH IS TO STACK GROVE PIs

GrovePi schematic shows using:
pin 3 GPIO0, 12C0_SDA,
pin 5 GPIO1, I2C0_SCL,
pin 8 GPIO14, UART0_TXD,
pin 10 GPIO15, UART0_RXD
pin 19 GPIO10_MOSI,
pin 21GPIO9_MISO,
pin 23GPIO11_SCLK,
pin 24 GPIO8, SPI0_CE0

which are all in the first 26 pins.

We start looking at pins 27 to 40 as possibles, but there are some dups to avoid.

That leaves:

pin 29 GPIO 05
pin 31 GPIO 06
pin 33 GPIO 13

pin 37 GPIO 26

pin 32 GPIO 12
pin 36 GPIO 16

And for a ground: pin 30 or pin 34 or pin 39.

RaspberryPiB_PinMap

GrovePi+ PinMap: