AXI GPIO can convert an AXI 4-Lite interface on the PS side into a GPIO interface and can be configured as single-port or dual-port, with each channel's bit width configurable independently. By enabling tri-state gates, the port can be dynamically configured as input or output.
AXIGPIO is an IP core on the ZYNQ PL side that can convert AXI-Lite Master to GPIO, and a single AXI-Lite interface can control multiple AXI-GPIOs through the AXI interconnect module.
AXI-GPIO IP Settings#
Maximum Clock Frequency#
The maximum frequency of $Zynq 7020$ is the same as the rate of $Artix 7-2$, which is $140 MHz$.
AXI GPIO Settings#
By default, it is single-channel. Once the direction of the GPIO is set here, it cannot be set in vitis. Interrupts belong to PL interrupts for PS and need to be checked in the ZYNQ 7 Processing System.
In the generated vitis code, the id in xparameters.h defaults to start from ID 0, regardless of whether the AXI-GPIO numbering in vivado starts from 0 or 1.
[!note]
- GPIO can only enable interrupts for the entire channel and cannot enable interrupts for a specific pin in the channel.
The interrupt type can only be set to rising edge or high level.
AXI-GPIO Related Code#
Initialization#
/****************************************************************************/
/**
* Initialize the XGpio instance provided by the caller based on the
* given configuration data.
*
* Nothing is done except to initialize the InstancePtr.
*
* @param InstancePtr is a pointer to an XGpio instance. The memory the
* pointer references must be pre-allocated by the caller. Further
* calls to manipulate the driver through the XGpio API must be
* made with this pointer.
* @param Config is a reference to a structure containing information
* about a specific GPIO device. This function initializes an
* InstancePtr object for a specific device specified by the
* contents of Config. This function can initialize multiple
* instance objects with the use of multiple calls giving different
* Config information on each call.
* @param EffectiveAddr is the device base address in the virtual memory
* address space. The caller is responsible for keeping the address
* mapping from EffectiveAddr to the device physical base address
* unchanged once this function is invoked. Unexpected errors may
* occur if the address mapping changes after this function is
* called. If address translation is not used, use
* Config->BaseAddress for this parameters, passing the physical
* address instead.
*
* @return
* - XST_SUCCESS if the initialization is successful.
*
* @note None.
*
*****************************************************************************/
int XGpio_CfgInitialize(XGpio * InstancePtr, XGpio_Config * Config,
UINTPTR EffectiveAddr)
Set Input/Output Direction#
/****************************************************************************/
/**
* Set the input/output direction of all discrete signals for the specified
* GPIO channel.
*
* @param InstancePtr is a pointer to an XGpio instance to be worked on.
* @param Channel contains the channel of the GPIO (1 or 2) to operate on.
* @param DirectionMask is a bitmask specifying which discretes are input
* and which are output. Bits set to 0 are output and bits set to 1
* are input.
*
* @return None.
*
* @note The hardware must be built for dual channels if this function
* is used with any channel other than 1. If it is not, this
* function will assert.
*
*****************************************************************************/
void XGpio_SetDataDirection(XGpio *InstancePtr, unsigned Channel, u32 DirectionMask)
GPIO Read/Write#
/****************************************************************************/
/**
* Read state of discretes for the specified GPIO channel.
* @param InstancePtr is a pointer to an XGpio instance to be worked on.
* @param Channel contains the channel of the GPIO (1 or 2) to operate on.
* @return Current copy of the discretes register.
* @note The hardware must be built for dual channels if this function
* is used with any channel other than 1. If it is not, this
* function will assert.
*****************************************************************************/
u32 XGpio_DiscreteRead(XGpio * InstancePtr, unsigned Channel)
/****************************************************************************/
/**
* Write to discretes register for the specified GPIO channel.
*
* @param InstancePtr is a pointer to an XGpio instance to be worked on.
* @param Channel contains the channel of the GPIO (1 or 2) to operate on.
* @param Mask is the value to be written to the discretes register.
*
* @return None.
*
* @note The hardware must be built for dual channels if this function
* is used with any channel other than 1. If it is not, this
* function will assert. See also XGpio_DiscreteSet() and
* XGpio_DiscreteClear().
*
*****************************************************************************/
void XGpio_DiscreteWrite(XGpio * InstancePtr, unsigned Channel, u32 Mask)