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CH32Vxxx GPIO overview

31 July 2025·720 words·4 mins·

Function Name	Purpose	When to use
`GPIO_DeInit(GPIO_TypeDef \*GPIOx)`	Resets the configuration of the specified GPIO port (A–E) to its default, power-on state by toggling the peripheral’s reset line.	At the start of a program to ensure the port has no prior configuration OR when you want to completely reconfigure a port from scratch.
`GPIO_AFIODeInit(void)`	Resets the Alternate Function registers (used for pin remapping, event output, EXTI config, etc.) for the entire chip.	To discard all pin remapping and alternate function configurations, e.g. before applying new ones.
`GPIO_Init(GPIO_TypeDef \GPIOx, GPIO_InitTypeDef \GPIO_InitStruct)`	Configures one or more pins on a GPIO port for input, output, alternate function, pull-up, pull-down, speed, etc., according to the passed GPIO_InitTypeDef.	At the start of your program to configure pins for your application (e.g. LEDs, buttons, peripherals) OR any time you need to change a pin’s mode.
`GPIO_StructInit(GPIO_InitTypeDef \*GPIO_InitStruct)`	Fills `GIO_InitTypeDef` struct with default settings (all pins as floating 2MHz input).	Before manual configuration, to ensure all structure fields are known states. Avoids issues from uninitialised structure fields.
`GPIO_ReadInputDataBit(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin)`	Reads the current logic level (`HIGH/LOW`) of a single input pin on the port.	To read the state of a button or digital sensor attached to the MCU.
`GPIO_ReadInputData(GPIO_TypeDef \*GPIOx)`	Reads the input values of all 16 pins on a GPIO port at once (returns as a 16-bit value).	To capture the entire state of a port, e.g. for a parallel input device or key matrix.
`GPIO_ReadOutputDataBit(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin)`	Reads the currently programmed output state (`HIGH/LOW`) of a specific pin, regardless of external hardware.	For “read-back” of your own outputs, e.g. to confirm a pin is programmed `HIGH` or `LOW`.
`GPIO_ReadOutputData(GPIO_TypeDef \*GPIOx)`	Reads the output register value (16 bits) for all port pins, i.e., bit pattern you last wrote.	To debug or keep track of programmed output states.
`GPIO_SetBits(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin)`	Sets one or more specific output pins `HIGH` (writes 1 to them).	To turn on an LED, drive a line `HIGH`, or activate an external circuit. Use bitwise OR to set multiple pins at once.
`GPIO_ResetBits(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin)`	Drives one or more output pins `LOW` (writes 0 to them).	To turn off an LED, deactivate a device, or bring a line `LOW`.
`GPIO_WriteBit(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin, BitAction BitVal)`	Sets or resets a single output pin according to the value (`Bit_SET` or `Bit_RESET`).	When you want to control a pin based on application logic.
`GPIO_Write(GPIO_TypeDef \*GPIOx, uint16_t PortVal)`	Directly sets the output value of the entire port (all 16 pins) using the bit pattern in PortVal.	Rapidly update all port outputs, such as driving a parallel bus or LEDs, in one instruction.
`GPIO_PinLockConfig(GPIO_TypeDef \*GPIOx, uint16_t GPIO_Pin)`	Locks the configuration of one or more pins—prevents accidental or intentional reconfiguration until the next reset.	After a pin is safely configured (especially for critical or multiplexed pins like JTAG/SWD or power controls). Helps comply with safety/security requirements.
`GPIO_EventOutputConfig(uint8_t GPIO_PortSource, uint8_t GPIO_PinSource)`	Selects which pin on which port to use for the chip’s “Event Output” function (used for sampling/triggering by other modules or debugging).	Rarely used in basic projects, but used when you need to signal events to other parts of the system or another microcontroller.
`GPIO_EventOutputCmd(FunctionalState NewState)`	Enables or disables the Event Output function after configuration.	Enable after calling `GPIO_EventOutputConfig`, or disable it when not needed.
`GPIO_PinRemapConfig(uint32_t GPIO_Remap, FunctionalState NewState)`	Remaps the function of selected pins—assigns alternate functions (like SPI, UART, TIM, CAN, etc.) to different pins per the MCU’s remap capabilities.	To move peripherals away from default pin assignments—needed for peripherals that conflict, add more devices, or customise board layout.
`GPIO_EXTILineConfig(uint8_t GPIO_PortSource, uint8_t GPIO_PinSource)`	Maps a specific GPIO pin to an external interrupt (`EXTI`) line, so it can trigger interrupts.	Configuring external interrupts, e.g. when you want an interrupt on a button press or sensor signal.
`GPIO_ETH_MediaInterfaceConfig(uint32_t GPIO_ETH_MediaInterface)`	Selects the Physical Layer interface for the Ethernet module: either MII (Media Independent Interface) or RMII (Reduced MII).	If using Ethernet, set this depending on your PHY/hardware design.
`GPIO_IPD_Unused(void)`	Automatically configures all unused GPIOs on the chip to be safe unused state (mainly input pull-up or pull-down), based on the detected chip variant.	At the very start of `main()`, it’s good practice to call this so all unused pins aren’t left floating (which saves power and avoids EMI/noise). Most users only need this once in system init.