It is time to write our first application c-program. The purpose of the program is to display "Hello World" on the LCD display. Let's get started. We will use the Software Development Kit (SDK) from Xilinx to help us accomplish the task. We start SDK from within Xilinx Platform Studio (XPS) using the menu command Software->Launch Platform Studio SDK.
To find out more about how to use SDK we select the Help menu.
When we click the Getting Started book the SDK design checklist is displayed in our web browser.
We are going to use available software drivers in our program. Let's find out how do that by studying the SDK design checklist.
SDK platform settings
Select Xilinx Tools->Software Platform Settings to look at the available software drivers and the current version used.
C program build
Select the menu Project->Properties to display the program build settings.
C header files
We find all header files in the directory .../SDK_projects/microblaze_0_sw_platform/microblaze_0/include.
The file xparameters.h holds information about the LCD_16x2 module. We will include this file in our c-program.
The header file xgpio.h contains the software API definition of the Xilinx General Purpose I/O (XGpio) device driver component. This file will also be included in our c-program.
C program examples
We are not going to re-invent the wheel. Let's look for some good examples to copy. In the directory .../edk91i/sw/XilinxProcessorIPLib/drivers/gpio_v2_01_a there are a few good ones.
More program examples
Looking in the directories of the reference system CD the following example files were found (xrom_lcd.c and xrom_lcd.h).
Let's use the functions declared in xrom_lcd.h.
Main program
//$$DEFINE /*************************************************************************/ /* */ /* I N C L U D E & D E F I N E */ /* */ /*************************************************************************/
// The following constant maps to the name of the hardware instances that // were created in the EDK XPS system. #define GPIO_LCD_DEVICE_ID XPAR_LCD_16X2_DEVICE_ID #define GPIO_LED4_DEVICE_ID XPAR_LEDS_4BIT_DEVICE_ID #define GPIO_LEDP_DEVICE_ID XPAR_LEDS_POSITIONS_DEVICE_ID
// The following constant is used to determine which channel of the GPIO is // used for the LCD if there are 2 channels supported.
#define LCD_CHANNEL 1 #define LED_CHANNEL 1
// The following are declared globally so they are zeroed and so they are // easily accessible from a debugger
XGpio GpioLCD; /* The Instance of the LCD GPIO Driver */ XGpio GpioLED4; /* The Instance of the LED4 GPIO Driver */ XGpio GpioLEDPOS; /* The Instance of the LED Pos GPIO Driver */ /$$MAIN /*************************************************************************/ /* */ /* M A I N P R O G R A M */ /* */ /*************************************************************************/
int main(void) {
XStatus Status; // Initialize the GPIO component Status = XGpio_Initialize(&GpioLCD, GPIO_LCD_DEVICE_ID); if (Status != XST_SUCCESS) return XST_FAILURE;
// Set the direction for all bits to be outputs XGpio_SetDataDirection(&GpioLCD, LCD_CHANNEL, 0x0000);
// Initialize the LCD XromLCDInit();
// Send single characters to the LCD print("Send Hello World to the LCD "); XromLCDPrintChar('H'); XromLCDPrintChar("e"); XromLCDPrintChar("l"); XromLCDPrintChar("l"); XromLCDPrintChar("o"); XromLCDPrintChar(" "); XromLCDPrintChar("W"); XromLCDPrintChar("o"); XromLCDPrintChar("r"); XromLCDPrintChar("l"); XromLCDPrintChar("d"); print("Hello World is displayed on the LCD display "); while(1);
return XST_SUCCESS; }
Device configuration in SDK
After we built our SDK project, we can download an Executable Linked Format (ELF) file for running or debugging on the target processor. To configure our hardware:
Specify the ELF file to be marked for block RAM (BRAM) initialization by selecting Device Configuration > Program Hardware Settings
Select the initialization file (Bootloop, XMDStub, or ELF file) and click Save.
To download the program bit file (download_sdk.bit) use the command: Device Configuration->Program Hardware.
Cavity Wall Insulations October 10, 2009 10:17 PM PDT Nice tutorial .. Just started my degree so will be very useful for me
Nabeel Khan October 10, 2009 10:16 PM PDT Great Work ... keep it up
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Ranga Prasad October 13, 2008 11:21 AM PDT Dear Svenand,
Thanks alot for superb and useful tutorial. I have a question. I have a Spartan 3 board with Xc3s2000 FPGA from AVNET. It has DMC20215 LCD. But I dont have any software driver file for LCD from AVNET like your Xrom_lcd.c. SHould I be provided with it or Do I need to write my own software driver which is little difficult? Please suggest me.
