Writing software for our embedded system

• Builds the directory structure as shown here below.
• Copies the necessary source files for the drivers, OSs, and libraries into the processor instance specific area: OUTPUT_DIR/processor_instance_name/libsrc.
• Calls the design rule check (defined as an option in the MDD or MLD file) procedure for each of the drivers, OSs, and libraries visible to the processor.
• Calls the generate Tcl procedure (if defined in the Tcl file associated with an MDD or MLD file) for each of the drivers, OSs, and libraries visible to the processor. This generates the necessary configuration files for each of the drivers, OSs, and libraries in the include directory of the processor.
• Calls the post_generate Tcl procedure (if defined in the Tcl file associated with an MDD or MLD file) for each of the drivers, OSs, and libraries visible to the processor.
• Runs make (with targets include and libs) for the OSs, drivers, and libraries specific to the processor. On Unix platforms (Linux and Solaris), the gmake utility is used, while on NT platforms, make is used for compilation.
• Calls the execs_generate Tcl procedure (if defined in the Tcl file associated with an MDD or MLD file) for each of the drivers, OSs, and libraries visible to the processor.
  

• Number of device instances
• Device ID for each instance
• A Device ID uniquely identifies each hardware device which maps to a device driver. A Device ID is used during initialization to perform the mapping of a device driver to a hardware device.
• Device IDs are typically assigned either by the user or by a system generation tool. It is currently defined as a 16-bit unsigned integer.
• Device base address for each instance
• Device interrupt assignment for each instance if interrupts can be generated.

Here is an example:

/* Definitions for peripheral RS232_UART */
#define XPAR_RS232_UART_BASEADDR 0x40600000
#define XPAR_RS232_UART_HIGHADDR 0x4060FFFF
#define XPAR_RS232_UART_DEVICE_ID 1
#define XPAR_RS232_UART_BAUDRATE 9600
#define XPAR_RS232_UART_USE_PARITY 0
#define XPAR_RS232_UART_ODD_PARITY 0
#define XPAR_RS232_UART_DATA_BITS 8

The xparameters.h file can be found in the include directory.




Software driver source code

During the library generation (

Source code repository




Software device drivers used

To find out which software device drivers are used we can open Software Platform Settings and select Drivers. In the Xilinx Platform Studio SDK select Xilinx Tools->Software Platform Settings. The ETC peripheral has a generic driver assigned as default. We will add our own driver.




SDK project directory

The specified version of the driver source code is stored in the libsrc directory.





Let's take the GPIO driver as an example and look at different source files and their usage.

Header source file (xgpio.h and xgpio_l.h)

The

• The external interfaces for the high level drivers (Layer 1) are contained in a header file with the file name format x<component name>.h.
• The external interfaces for the low level drivers (Layer 0) are contained in a header file with the file name format x<component name>_l.h.

. The functions themselves are defined in the different .c files found in the gpio source directory.

/************************** Function Prototypes *****************************/

/*
 * Initialization functions in xgpio_sinit.c
 */
XStatus XGpio_Initialize(XGpio *InstancePtr, Xuint16 DeviceId);
XGpio_Config *XGpio_LookupConfig(Xuint16 DeviceId);

/*
 * API Basic functions implemented in xgpio.c
 */
XStatus XGpio_CfgInitialize(XGpio *InstancePtr, XGpio_Config *Config,
                            Xuint32 EffectiveAddr);
void    XGpio_SetDataDirection(XGpio *InstancePtr, unsigned Channel,
                               Xuint32 DirectionMask);
Xuint32 XGpio_DiscreteRead(XGpio *InstancePtr, unsigned Channel);
void    XGpio_DiscreteWrite(XGpio *InstancePtr, unsigned Channel, Xuint32 Mask);


Configuration table xgpio_g.c

This file contains configuration tables for all devices that uses the GPIO device driver.

/*
* The configuration table for devices
*/

XGpio_Config XGpio_ConfigTable[] =
{
    {
        XPAR_LEDS_4BIT_DEVICE_ID,
        XPAR_LEDS_4BIT_BASEADDR,
        XPAR_LEDS_4BIT_INTERRUPT_PRESENT,
        XPAR_LEDS_4BIT_IS_DUAL
    },
    {
        XPAR_LEDS_POSITIONS_DEVICE_ID,
        XPAR_LEDS_POSITIONS_BASEADDR,
        XPAR_LEDS_POSITIONS_INTERRUPT_PRESENT,
        XPAR_LEDS_POSITIONS_IS_DUAL
    },
    {
        XPAR_PUSH_BUTTONS_POSITION_DEVICE_ID,
        XPAR_PUSH_BUTTONS_POSITION_BASEADDR,
        XPAR_PUSH_BUTTONS_POSITION_INTERRUPT_PRESENT,
        XPAR_PUSH_BUTTONS_POSITION_IS_DUAL
    },
    {
        XPAR_LCD_16X2_DEVICE_ID,
        XPAR_LCD_16X2_BASEADDR,
        XPAR_LCD_16X2_INTERRUPT_PRESENT,
        XPAR_LCD_16X2_IS_DUAL
    }
};

Adding the ETC software device driver

From the Xilinx documentation it isn't 100% clear how to add a new device driver. Here is how I did it and it seems to work.

1. Edit the ETC_system.mss file and add the etc driver. Like this:

   BEGIN DRIVER
     PARAMETER DRIVER_NAME = etc
     PARAMETER DRIVER_VER = 1.00.a
     PARAMETER HW_INSTANCE = ETC_0
  END

2. Add a new directory called drivers and the subdirectories as shown here: