I²C Sensors
Inertial measurement sensor: ST LSM9DS1 data sheet. This is a 3D accelerometer, 3D gyroscope and 3D magnetometer combined in one chip. It provides the pitch, roll and yaw orientation of Sense HAT.
Barometric pressure and temperature sensor: ST LPS25H data sheet. This provides a measurement of air pressure in Pascals or Millibars, plus, temperature in centigrade.
Relative humidity and temperature sensor: ST HTS221 data sheet. This provides the percentage of relative humidity, as well as, the temperature in centigrade.
Outputs
8×8 RGB LED matrix with ~60fps refresh rate and 15-bit colour resolution (RGB 5 5 5): Cree CLU6AFKW/CLX6AFKB data sheet
Accessible via frame buffer driver /dev/fb1 where each pixel is 16 bit (RGB 5 6 5). This is the only real form of visual output that the Sense HAT has unless plugged into an HDMI monitor
Micro controller A small MCU drives the LED matrix and scans for joystick input: Atmel ATTINY88 data sheet
https://projects.raspberrypi.org/en/projects/getting-started-with-the-sense-hat/9