Frequently Asked Questions
Q1: What does the ClusterHAT come with and what do I need to use it?
A1:The ClusterHAT is supplied with 4*12mm M2.5 spacers and 8*6mm M2.5 screws to secure the ClusterHAT to your Raspberry Pi. You will need to supply your own USB cable (at least 20cm) and stick on feet (to prevent the screws from scratching the table surface) should they be required. You will also obviously need to provide your own controlling Pi (A+/B+/2/3), 1 to 4 Pi Zeros and associated micro SD cards/etc.
Q2: Can the ClusterHAT be used with a Raspberry Pi 2 (v1.2) or 3?
A2:The ClusterHAT can be used with a Raspberry Pi 2 (v1.2) and 3 but please be aware the Pi may get HOT when covered by the HAT causing the CPU speed to be reduced (towards 600Mhz). The Raspberry Pi 2 (v1.1) is less likely to reach temperatures high enough to throttle the CPU frequency.
Q3: How do I use the serial console connector?
A3:The serial console connector can be used with either our USB Serial board or the Sparkfun FTDI Basic 3.3V or Sparkfun Beefy 3. The 5V version MUST NOT be used since the Raspberry Pi GPIO are only 3.3V tolerant.
Q4: What are the solder bridge/jumpers for?
Cluster HAT v2.x
  • PWR (Power) is normally JOINED between RPi and the center pad, this can be CUT to allow powering from the 6 way SMD connector on the underside, or if CUT the center pad can be joined to USB to power via the Micro USB connector. If must be left open or connected to one side only.
  • WP (Write Protect) is normally OPEN to allow EEPROM Write Protect to be controlled via the I/O Expander. If joined it will prevent the EEPROM from being written to.
  • POS (Power On State) is normally JOINED which means the Pi Zeros are not powered on by default, if CUT the Pi Zeros will power on once power is applied to the Controller.
Cluster HAT v1.x
  • The 2 way PWR solder bridge is used to select the power source for the Pi Zeros. Bridging "USB" to the centre pad will source power from the female Micro USB connector, bridging "RPi" to the centre pad (the default) will source power via the 5V GPIO header (you must bridge only one option).
Cluster AT <= v1.1
  • "W EN" when bridged allows the HAT EEPROM to be modified.
Q5: Which Raspberry Pi models can I use for the controller?
A5:You can use any Raspberry Pi model with a 40 pin GPIO header to control the ClusterHAT - A+/B+/2/3 or even another Raspberry Pi Zero although it's not very practical.
Q6: Do I need an SD card for each Raspberry Pi Zero?
A6:Currently an SD card is needed for every Pi Zero unless using the currently beta usbboot/rpiboot image.
Q7: Why do you only use one micro USB connector on the Pi Zero?
A7:The "USB" connector can be used for both power and data (the "PWR" connector is power only). The "USB" and "PWR" connectors are connected together via a 0R resistor on the Zero. There is also no power protection circuitry on the Pi Zero so powering via GPIO, USB or PWR connectors is effectively the same.
Q8: Can I use a Camera on a Pi Zero 1.3 / W?
A8:Yes, you will need to enable the camera as normal using "sudo raspi-config".
Q9: What PSU do you recommend?
A9:For the Pi A+/B+ and old model Pi2 (with BCM2836) we recommend using a 2A PSU and for the newer Pi2 (BCM2837) and Pi3 a 2.4A PSU.
Q10: What is the I2C address of the I/O Expander on Cluster HAT v2.x?
A10:We use the Exar XRA1200P I/O expander on address 0x20