Raspberry Pi Sense HAT With Jumpers

I just got a Raspberry Pi Zero W, and I had a Sense HAT sitting around (as they tend to do). I wanted to use the HAT, but I also wanted to be able to light some separate LEDs or add other sensors (like ultrasonic sensors). Putting on the HAT made all of the pins inaccessible. The cable was no help.

Several sites suggested using a stackable or extended header. This makes all of the pins accessible on the top of the HAT. Cool idea, but did not have a extended 2×20 header sitting around (beside my sense HAT or anywhere else).

I thought it must be possible to just use jumpers. After some amount of research, this is what I came up with...

• Raspberry Pi with 40 pins (I used a Zero W)
• Sense HAT
• 11 jumper wires

The 40 pins on the Sense HAT are arranged just as the 40 pins on the Raspberry Pi.

The Sense HAT requires 3.3V, 5V, and GND.

• pin 1 to pin 1 -- 3.3V
• pin 2 to pin 2 -- 5V
• pin 6 to pin 6 -- GND (really any of the eight GND pins would do)

There are two pins for I²C communication:

• pin 3 to pin 3 -- GPIO2 or SDA
• pin 5 to pin 5 -- GPIO3 or SCL

Some documentation (pinout.xyz) indicated that you could access all the sensors directly using their I²C addresses:

• 0x5c: lps25h -- LPS25H Pressure/Temperature sensor
• 0x1c: lsm9ds1 -- IMU (Accelerometer and Magnetometer)
• 0x5f: hts221 -- HTS221 Humidity/Temperature sensor
• 0x46: led2472g -- shift register driving the LED Matrix
• 0x6a: lsm9ds1 -- IMU (Accelerometer and Magnetometer)

Other sources stated that these two pins (and the three power pins) are the minimum needed to access the sensors. However, I found that I could not use the Sense_Hat library without all eleven pins (see next steps) connected.

Various sources stated that these pins need to be connected:

• pin 16 to pin 16 -- GPIO23 (IMU Interupt)
• pin 18 to pin 18 -- GPIO24 (IMU Interupt)
• pin 22 to pin 22 -- GPIO25 (Atmel Prog Reset)
• pin 24 to pin 24 -- GPIO8 (Atmel Chip Reset)

One site (Ms. Haughs) said that there are two final pins that need connecting:

• pin 27 to pin 27 -- GPIO0 (or maybe ID_SD or maybe EEPROM SDA or maybe HAT ID)
• pin 28 to pin 28 -- GPIO1 (or maybe ID_SC or maybe EEPROM SCL or maybe HAT ID)

I trusted her, and I connected these pins and everything worked fine. Another site said these two pins were DNC (I presume, do not connect). However, I found that with out these pins connected, odd things happened (error messages; the LEDs did not turn off).

As far as I can tell, the Raspberry Pi Sense HAT only uses eight distinct pins (plus three for power that can be shared). This leaves quite a number of pins (maybe even twenty) open. In the picture I have three working 3mm LEDs, and I had a separate HTS221 connect as well.