SD card support on FX2 based Series 2 FPGA Boards

ZTEX uses the FX3S on its FPGA Boards. These boards have native SD card support (including SDIO).

On FX2 based based Series 2 FPGA Boards there is no SD socket. Users that miss it (e.g. because they previously used Series 1 Boards) can easily add a (micro)SD socket to their application circuit.

This page described how this is done and how firmware support is activated. This is explained best by an example:

A SD card is connected to an USB-FPGA Module 2.01 as follows

Signal	pin	FPGA pin	direction	pin	FPGA pin
	External I/O			FX2 I/O
CS	B13	K15	← (in)	PC1	N12
DI	B14	J13	← (in)	PC2	P12
CLK	B18	J14	← (in)	PC3	N5
DO	B19	H15	→ (out)	PA2	H15

The HDL code for routing the signals is:

# ...
 
NET "pa2"	LOC = "B10" | IOSTANDARD = LVCMOS33 ;		# PA2
NET "pc1"	LOC = "N12" | IOSTANDARD = LVCMOS33 ;		# PC1/GPIFADR1
NET "pc2"	LOC = "P12" | IOSTANDARD = LVCMOS33 ;		# PC2/GPIFADR2
NET "pc3"	LOC = "N5" | IOSTANDARD = LVCMOS33 ;		# PC3/GPIFADR3
 
NET "b13"	LOC = "K15" | IOSTANDARD = LVCMOS33 ;	
NET "b14"	LOC = "J13" | IOSTANDARD = LVCMOS33 ;
NET "b18"	LOC = "J14" | IOSTANDARD = LVCMOS33 ;
NET "b19"	LOC = "H15" | IOSTANDARD = LVCMOS33 ;
 
# ...

(.ucf constraints file) and

// ...
 
module top (
 
        // ...
 
	input pc1,pc2,pc3, b19,
	output b13,b14,b18, pa2
    );
 
    // ...
 
    assign b13 = pc1;
    assign b14 = pc2;
    assign b18 = pc3;
    assign pa2 = b19;
 
    // ...
 
endmodule

(verilog HDL file).

In order to enable firmware support the following lines have to be inserted between #include[ztex-conf.h] and #include[ztex.h]

ENABLE_FLASH2;            // enables SD support as secondary Flash
#define[MMC_PORT][C]      // Port for input signals, valid values: A..D
#define[MMC__PORT_DO][A]  // Port for output signals (valid values: A..D,
                          // can be omitted if equal to input port)
#define[MMC_BIT_CS][1]    // Pin number for CS signal, i.e. PC1
#define[MMC_BIT_DI][2]    // Pin number for DI signal, i.e. PC2
#define[MMC_BIT_DO][2]    // Pin number for DO signal, i.e. PA2
#define[MMC_BIT_CLK][3]   // Pin number for CLK signal, i.e. PC3

From the firmware the SD card now can be accessed using the functions flash2_read_init, flash2_read, flash2_read_finish,flash2_write_init, flash2_write, flash2_write_finish. The syntax is is the same as of flash_read_* and flash_write_* functions.

From host software the SD card can be accessed using then functions flash2* (which are equivalent to the functions for primary flash).

Their usage can be explained with flashdemo example ported to secondary flash. The firmware code is:

#include[ztex-conf.h]	// Loads the configuration macros, see ztex-conf.h for the available macros
#include[ztex-utils.h]	// include basic functions and variables
 
// select ZTEX USB FPGA Module 2.01 as target  (required for FPGA configuration)
IDENTITY_UFM_2_01(10.18.0.0,0);	 
 
// enable Flash support
ENABLE_FLASH;
ENABLE_FLASH_BITSTREAM;
 
ENABLE_FLASH2;            // enables SD support as secondary Flash
#define[MMC_PORT][C]      // Port for input signals, valid values: A..D
#define[MMC__PORT_DO][A]  // Port for output signals (valid values: A..D,
                          // can be omitted if equal to input port)
#define[MMC_BIT_CS][1]    // Pin number for CS signal, i.e. PC1
#define[MMC_BIT_DI][2]    // Pin number for DI signal, i.e. PC2
#define[MMC_BIT_DO][2]    // Pin number for DO signal, i.e. PA2
#define[MMC_BIT_CLK][3]   // Pin number for CLK signal, i.e. PC3
 
// this product string is also used for identification by the host software
#define[PRODUCT_STRING]["Flash2 demo for UFM 2.01"]
 
__code char flash2_string[] = "Hello World!";
 
// include the main part of the firmware kit, define the descriptors, ...
#include[ztex.h]
 
void main(void)	
{
    __xdata DWORD sector;
 
    init_USB();						// init everything
 
    if ( flash2_enabled ) {
	flash2_read_init( 0 ); 				// prepare reading sector 0
	flash2_read((__xdata BYTE*) &sector, 4); 	// read the number of last sector 
	flash2_read_finish(flash2_sector_size - 4);	// dummy-read the rest of the sector + finish read operation
 
	sector++;
	if ( sector > flash2_sectors || sector == 0 ) {
	    sector = 1;
	}
 
	flash2_write_init( 0 ); 				// prepare writing sector 0
	flash2_write((__xdata BYTE*) &sector, 4); 		// write the current sector number
	flash2_write_finish_sector(flash2_sector_size - 4);	// dummy-write the rest of the sector + CRC
	flash2_write_finish();					// finish write operation
 
	flash2_write_init( sector ); 						// prepare writing sector sector
	flash2_write((__xdata BYTE*) flash2_string, sizeof(flash2_string)); 	// write the string 
	flash2_write_finish_sector(flash2_sector_size - sizeof(flash2_string));	// dummy-write the rest of the sector + CRC
	flash2_write_finish();							// finish write operation
    }
 
    while (1) {	}					//  twiddle thumbs
}

and the host software is defined by

import java.io.*;
import java.util.*;
 
import ch.ntb.usb.*;
 
import ztex.*;
 
// *****************************************************************************
// ******* ParameterException **************************************************
// *****************************************************************************
// Exception the prints a help message
class ParameterException extends Exception {
    public final static String helpMsg = new String (
		"Parameters:\n"+
		"    -d <number>  Device Number (default: 0)\n" +
		"    -f 	  Force uploads\n" +
		"    -p           Print bus info\n" +
		"    -ue          Upload Firmware to EEPROM\n" +
		"    -re          Reset EEPROM Firmware\n" +
		"    -w           Enable certain workarounds\n" +
		"    -h           This help" );
 
    public ParameterException (String msg) {
	super( msg + "\n" + helpMsg );
    }
}
 
// *****************************************************************************
// ******* Test0 ***************************************************************
// *****************************************************************************
class FlashDemo extends Ztex1v1 {
 
// ******* FlashDemo ***********************************************************
// constructor
    public FlashDemo ( ZtexDevice1 pDev ) throws UsbException {
	super ( pDev );
    }
 
// ******* main ****************************************************************
    public static void main (String args[]) {
 
	int devNum = 0;
	boolean force = false;
	boolean workarounds = false;
 
	try {
// init USB stuff
	    LibusbJava.usb_init();
 
// scan the USB bus
	    ZtexScanBus1 bus = new ZtexScanBus1( ZtexDevice1.ztexVendorId, ZtexDevice1.ztexProductId, true, false, 1);
	    if ( bus.numberOfDevices() <= 0) {
		System.err.println("No devices found");
	        System.exit(0);
	    }
 
// scan the command line arguments
    	    for (int i=0; i<args.length; i++ ) {
	        if ( args[i].equals("-d") ) {
	    	    i++;
		    try {
			if (i>=args.length) throw new Exception();
    			devNum = Integer.parseInt( args[i] );
		    } 
		    catch (Exception e) {
		        throw new ParameterException("Device number expected after -d");
		    }
		}
		else if ( args[i].equals("-f") ) {
		    force = true;
		}
		else if ( args[i].equals("-p") ) {
	    	    bus.printBus(System.out);
		    System.exit(0);
		}
		else if ( args[i].equals("-w") ) {
	    	    workarounds = true;
		}
		else if ( args[i].equals("-h") ) {
		        System.err.println(ParameterException.helpMsg);
	    	        System.exit(0);
		}
		else if ( !args[i].equals("-re") && !args[i].equals("-ue") )
		    throw new ParameterException("Invalid Parameter: "+args[i]);
	    }
 
 
// create the main class	    
	    FlashDemo ztex = new FlashDemo ( bus.device(devNum) );
	    ztex.certainWorkarounds = workarounds;
 
// upload the firmware if necessary
	    if ( force || ! ztex.valid() || ! ztex.dev().productString().equals("Flash2 demo for UFM 2.01")  ) {
		System.out.println("Firmware upload time: " + ztex.uploadFirmware( "flashdemo.ihx", force ) + " ms");
	    }	
 
    	    for (int i=0; i<args.length; i++ ) {
		if ( args[i].equals("-re") ) {
		    ztex.eepromDisable();
		} 
		else if ( args[i].equals("-ue") ) {
		    System.out.println("Firmware to EEPROM upload time: " + ztex.eepromUpload( "flashdemo.ihx", force ) + " ms");
		}
	    }
 
// print some information
	    System.out.println("Capabilities: " + ztex.capabilityInfo(", "));
	    System.out.println("Enabled: " + ztex.flash2Enabled());
	    System.out.println("Size: " + ztex.flash2Size());
	    ztex.printMmc2State();
 
	    if ( ztex.getFlash2EC() == ztex.FLASH_EC_PENDING ) {
		System.out.print("Another operation is pending. Waiting ..");
		int i = 20;
		do {
		    System.out.print(".");
		    try {
    			Thread.sleep( 1000 );
    		    }
		    catch ( InterruptedException e) {
    		    } 
    		    i--;
		} while ( ztex.getFlash2EC()==ztex.FLASH_EC_PENDING && i>0 );
		System.out.println();
	    }
 
	    byte[] buf = new byte[ztex.flash2SectorSize()];
	    ztex.flash2ReadSector(0,buf);		// read out the last sector;
	    int sector = (buf[0] & 255) | ((buf[1] & 255) << 8) | ((buf[1] & 255) << 16) | ((buf[1] & 255) << 24);
	    System.out.println("Last sector: "+sector);
 
	    ztex.flash2ReadSector(sector,buf);		// read out the string
	    int i=0;
	    while ( buf[i] != '\0'&& i < ztex.flash2SectorSize() )
	        i++;
	    System.out.println("The string: `" + new String(buf,0,i)+ "'");
	}
	catch (Exception e) {
	    System.out.println("Error: "+e.getLocalizedMessage() );
	} 
   } 
 
}