GPIO & modules

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You can use your Flipper Zero for hardware exploration, firmware flashing, debugging, and fuzzing. Flipper Zero can be connected to hardware using its built-in GPIO pins, control hardware with buttons, run your code, and show debug messages on the LCD screen. Flipper Zero can also be used as a USB to UART/SPI/I2C converter.
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GPIO pinout
Flipper Zero has 18 pins on the top side, consisting of power supply pins and I/O pins. Power supply pins can be used to power your external modules. Input/output (I/O) pins are +3.3 V tolerant for input and output. For more information, see 3.3 V and 5 V tolerance.
I/O pins connect external modules to the I/O pins of the STM32WB55 microcontroller through 51 Ohm resistors. All pins are electrostatic discharge (ESD) protected. For information on the basic functionality of Flipper Zero pins, see the picture below.
Flipper Zero's pins
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Detailed information on the pinout and functionality of the pins can be found in the picture below.
Flipper Zero's pinout
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<div class="info flipper-callout">
    <div class="callout-header">I/O pins change their state in DFU mode</div>
    When Flipper is in DFU mode, the microcontroller I/O pins, except for pin 17, change their state according to the table below.</div>
<div class="info flipper-callout">
    <div class="callout-header">I/O pins change their state in DFU mode</div>
    When Flipper is in DFU mode, the microcontroller I/O pins, except for pin 17, change their state according to the table below.</div>
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Table: Configuration in DFU mode (expandable)
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Source: AN2606 Application note STM32 microcontroller system memory boot mode, Table 152. STM32WB30xx/35xx/50xx/55xx configuration in system memory boot mode, section 70.1.
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+3.3 V power (pin 9)
The output is enabled by default. 

The maximum load is 1.2 A.

Flipper Zero's microSD card is powered by +3.3 V. During firmware updates and microSD card mounting, the power supply to pin 9 is temporarily disabled.
<div class="warning flipper-callout">
    <div class="callout-header"></div>
    Connect external modules with large capacitive load only when Flipper Zero is powered off. Otherwise, data on the microSD card can be corrupted.
</div>
<div class="warning flipper-callout">
    <div class="callout-header"></div>
    Connect external modules with large capacitive load only when Flipper Zero is powered off. Otherwise, data on the microSD card can be corrupted.
</div>
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+5 V power (pin 1)
Pin 1 can be supplied with power by the built-in battery or a USB cable.
<div class="warning flipper-callout">
    <div class="callout-header"></div>
    When Flipper Zero is connected to a USB cable, then the power to pin 1 is supplied directly from USB. Never exceed the maximum current of 1 A.
</div>
<div class="warning flipper-callout">
    <div class="callout-header"></div>
    When Flipper Zero is connected to a USB cable, then the power to pin 1 is supplied directly from USB. Never exceed the maximum current of 1 A.
</div>
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When Flipper Zero is powered by the built-in battery:
The output is not enabled by default. To enable power supply to pin 1, do the following:

    1. In the Main Menu, go to GPIO.

    2. Select 5V on GPIO and set it to ON.

The maximum load is 1 A. 
Input/output pins
Total power consumption from I/O pins must not exceed 5 W, otherwise, the battery might switch to the protection mode and Flipper Zero might shut down. Each pin can source up to 20 mA.
3.3 V and 5 V tolerance
The I/O interface of modern CMOS chips is designed to operate in a specific voltage range. In the case of Flipper Zero's MCU STM32WB55, its I/O interface is designed to operate with a voltage of 3.3 V.
<div class="warning flipper-callout">
    <div class="callout-header">Avoid connecting 5 V I/O peripherals to your Flipper Zero to prevent potential damage</div>
     The only exception is when a specific GPIO pin is configured for input, then it becomes 5 V tolerant. When the GPIO pin is configured for output, it is no longer 5 V tolerant.
</div>
<div class="warning flipper-callout">
    <div class="callout-header">Avoid connecting 5 V I/O peripherals to your Flipper Zero to prevent potential damage</div>
     The only exception is when a specific GPIO pin is configured for input, then it becomes 5 V tolerant. When the GPIO pin is configured for output, it is no longer 5 V tolerant.
</div>
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For more information, see AN4899 Application note.
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GPIO menu
You can access the GPIO application from the Main Menu. In the application, you can configure USB-UART functionality, test pins separately, and enable/disable the +5 V power supply to pin 1.
GPIO application menu
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USB-UART Bridge — Flipper Zero acts as a USB to Serial UART converter.
GPIO Manual Control — test output of individual or all GPIO pins by pressing %ok%OK. Available configuring options: PA7 (pin 2), PA6 (pin 3), PA4 (pin 4), PB3 (pin 5), PB2 (pin 6),  PC3 (pin 7), PC1 (pin 15), PC0 (pin 16), and ALL.
5V on GPIO — enable/disable +5 V power supply to pin 1. See this section for more information.
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Inserting an external module
It's important to insert the external module into your Flipper Zero's GPIO pin holes correctly. If your Flipper Zero isn't in a silicone case, insert the module all the way in, so there is no gap between your Flipper Zero and the module. You may need to apply more force to insert it completely.
Make sure the module's GPIO pins aren't visible
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If your Flipper Zero is in a silicone case, insert the module all the way in, so there is no gap in the middle between the silicone case and the module.
Make sure there is no gap in the middle
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﻿Flipper Zero schematics﻿
﻿GPIO application source code﻿
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