A fast personal reference. Not a datasheet, and not a guarantee of correctness. Pinouts on the internet are often simplified, out of date or specific to one board variant. The datasheet and your board's schematic are the source of truth. Raspberry Pi GPIO is 3.3 V and not 5 V tolerant, with no protection between the header and the SoC. Open for the full scope limits.
What this page is
- Pinouts on the internet are often simplified, out-of-date, or board-variant-specific. Use the datasheet and TRM, and the board schematic where one is available, as the source of truth.
- Some boards vary by manufacturer and revision, especially CM4 and CM5 carrier boards. Always verify your exact PCB rather than a board with the same name.
- This tool is a personal fast reference. It is not a guarantee of correctness.
On a Compute Module the header belongs to the carrier board, not to the module. The same GPIO can appear on a different physical pin, or on none at all, depending on whose carrier you bought.
The pins that bite
- 3.3 V logic, not 5 V tolerant. There is no series resistor, no clamp and no level shifter between the header and the SoC. One 5 V signal on a GPIO can kill the processor, and the board will not tell you which pin did it.
- Two numbering schemes. Physical or BOARD numbering counts pins along the header; BCM or GPIO numbering names the SoC line. They do not agree, and mixing them is the single most common wiring error on this platform. Pin 3 is GPIO2.
- Fixed pull-ups on the I2C pins. GPIO2 and GPIO3, physical pins 3 and 5, carry board-mounted pull-ups to 3.3 V. They are not general purpose inputs, and adding your own pull-ups on that bus changes the rise time.
- Boot and alternate functions. Several pins have a defined state at boot or are claimed by an overlay, a HAT EEPROM, serial console or SPI. A pin free in your code may not be free in the running system.
- Current limits are small. The per-pin and total GPIO current limits are commonly quoted as 16 mA per pin and about 50 mA across all pins, and they vary by model. The 3.3 V header rail is shared and weak. Drive anything real through a transistor or a driver, not a GPIO.
- Header length varies. The 40-pin header is standard from the B+ onward; earlier 26-pin boards, the Zero range and the Compute Modules are not the same, and the Pi 5 changed the underlying I/O.
Never use this page as the basis for
- Production hardware, a HAT design, a PCB layout or a bill of materials, without checking every pin against the current datasheet and the board schematic.
- Anything connected to mains, to a battery pack that can deliver fault current, or to a motor or heater.
- Safety, medical, automotive or life-critical functions of any kind.
- Certification, compliance or regulatory submissions.
Before you wire anything
Open the datasheet for your exact model and the schematic for your exact board revision, and for a Compute Module the schematic for the carrier as well. Confirm the pin function, the numbering scheme you are using, the voltage and the current limit there. Measure before you connect anything you did not build.