Raspberry Pi HATs make expansion straightforward, but physical compatibility alone does not guarantee that two products will work together. A short checklist can prevent conflicts before the hardware is assembled.
Confirm the supported Raspberry Pi model
Check the board generation, header layout and any model-specific limitations. A HAT designed around an older model may still fit a newer board while depending on software, power behaviour or connector clearances that have changed.
Map every GPIO resource
List the pins used for I2C, SPI, UART, interrupts, chip selects and power control. Two HATs can share a physical header but compete for the same address or control pin. When stacking is required, review address configuration and pass-through headers before purchase.
Calculate the power budget
Include the Raspberry Pi, the HAT and all connected peripherals. Motors, radios, displays and USB devices can create short peaks that exceed the average estimate. Follow the HAT manufacturer’s power-input guidance and avoid feeding the system through multiple uncoordinated sources.
Check software and maintenance
Verify operating-system support, required overlays, kernel modules and example code. A maintained library and clear documentation can matter more than a small difference in hardware specifications, especially when the system must be updated later.
Inspect the enclosure stack
Allow for standoffs, connectors, cable bends, cooling and access to buttons or removable storage. A simple mechanical sketch is often enough to reveal conflicts before assembly.