barcode reader in asp.net Possible Alternatives in Software

Maker Code 128 Code Set B in Software Possible Alternatives

16.5 Possible Alternatives
Code 128 Code Set A Recognizer In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Make Code128 In None
Using Barcode printer for Software Control to generate, create Code 128 image in Software applications.
We have used 8-pin processors in this application to reduce size. However, from the point of view of current consumption, that may not be the best choice. AT90S1200A (or the AT90S1200 with its internal 1-MHz RC oscillator) may consume less current than the
Read Code 128 Code Set B In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Code128 Generator In Visual C#.NET
Using Barcode encoder for .NET framework Control to generate, create Code-128 image in VS .NET applications.
POSSIBLE ALTERNATIVES 287
Creating Code 128 Code Set C In VS .NET
Using Barcode generator for ASP.NET Control to generate, create Code 128 image in ASP.NET applications.
Creating Code 128 Code Set C In Visual Studio .NET
Using Barcode generation for Visual Studio .NET Control to generate, create Code 128 Code Set C image in VS .NET applications.
Strobe signal from the PC
Code 128 Generation In Visual Basic .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create Code 128 Code Set A image in Visual Studio .NET applications.
GS1-128 Creation In None
Using Barcode printer for Software Control to generate, create UCC-128 image in Software applications.
PC puts serial data on D0 (pin2) of the parallel port
Create Barcode In None
Using Barcode creator for Software Control to generate, create bar code image in Software applications.
Encode Code 39 In None
Using Barcode encoder for Software Control to generate, create Code-39 image in Software applications.
Data echoed by the controller 1.2V shift
Create Data Matrix ECC200 In None
Using Barcode creator for Software Control to generate, create Data Matrix ECC200 image in Software applications.
European Article Number 13 Creation In None
Using Barcode printer for Software Control to generate, create EAN-13 Supplement 5 image in Software applications.
FIGURE 16.10 Scope trace shows 8 bits of data set up by the PC while sending to the processor and the return data generated by the processor.
International Standard Book Number Creator In None
Using Barcode creator for Software Control to generate, create International Standard Book Number image in Software applications.
UCC-128 Decoder In VB.NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in .NET framework applications.
Strobe from PC for 2 byte transfer
Code 128B Generator In None
Using Barcode creator for Online Control to generate, create Code128 image in Online applications.
Make Data Matrix In Java
Using Barcode generator for Java Control to generate, create DataMatrix image in Java applications.
Strobe from PC for getting the LFSR result
Print Bar Code In Visual Studio .NET
Using Barcode maker for Visual Studio .NET Control to generate, create barcode image in .NET applications.
Barcode Generator In VS .NET
Using Barcode creation for ASP.NET Control to generate, create barcode image in ASP.NET applications.
Controller busy calculating the LFSR result Ack from controller for the receipt of bytes Controller done. Ack for the result
Creating UCC.EAN - 128 In .NET
Using Barcode generation for ASP.NET Control to generate, create UCC.EAN - 128 image in ASP.NET applications.
Print Code 39 Extended In Visual Studio .NET
Using Barcode generator for ASP.NET Control to generate, create Code 39 Extended image in ASP.NET applications.
FIGURE 16.11 The scope trace shows how the processor can delay the data transfer back to the PC by asserting the Ack signal. When Ack signal remains 1, the PC waits for it to go 0 before asserting the strobe signal to 1.
Tiny22 or the AT90S2343. This is because that the 1200 device does not have any SRAM and has less EEPROM than either of the two 8-pin devices. From the point of view of implementation, one could implement a longer LFSR without much impact on the processor code size. Another possible alternative is to put the dongle on the PC serial port. The schematic for just such a design is illustrated in Figure 16.12. The serial-port-based dongle is implemented using the AT90S2323 with an external 3.58-MHz crystal (nothing special about this value; in fact, any other could be used as well
288 AVR PROJECT 7: SECURITY DONGLE
FIGURE 16.12 Circuit schematic for the PC RS-232 serial-port-based security lock using AT90S2323.
with suitable modifications to the software) rather than use an AT90S2343 with the internal RC clock oscillator. This is because the RC oscillator frequency is supply-voltage dependent, and since the power supply is derived out of the serial port pins, which varies, it does not give a constant data transfer rate, which is critical for data transfer on the RS232 port. To alleviate this problem, the lock was implemented using an AT90S2323 with an external crystal. The serial data transmission from the processor was implemented using the bit banging scheme we discussed in a previous chapter. The data transfer baud rate was selected as 9600 bps, 8 data bits, no parity, and 1 stop bit.
16.6 Fabrication
This little circuit was fabricated on a single-side general-purpose PCB as seen in Figure 16.13. The 25-pin D-type connector was soldered directly onto the PCB.
16.7 Design Code
The code for this project is available in the code directory in the file dongle1.asm for the AVR processor as well as the PC as a file dongle.c. The PC code is in C and was tested on a 100-MHz pentium running DOS with a Turbo C version 2.0 compiler from Borland. The PC driver lacks many features, such as device timeout. As it is, the PC waits indefinitely for the processor to respond. In real application, the PC should wait for some worst-case
TESTING 289
FIGURE 16.13 Photograph of the security dongle.
time and should report Dongle not found otherwise. However, the PC code is illustrated only to highlight the kind of code that will be required to communicate with the processor through the parallel port.
16.8 Testing
Testing this particular application turned out to be a nightmare for me not because of bad design or code bugs but because of a faulty power supply. I used this rather expensive 5V linear-type power supply to power the lock circuit. However, when I switched the power supply off, it damaged the processor (which was discovered when the supply was switched on again and the processor failed to respond to the PC code) due to excessive overvoltage. Another processor was tried and it met the same fate. I then checked the circuit for any possible short circuits and, finding none, began suspecting the power supply. Sure enough, the supply showed 13-V output for a considerable time when it was switched off. This was captured on the scope and is illustrated in Figure 16.14. Other than this, the system performed as desired. The processor results were checked against the expected output of an 8-bit LFSR simulator. The C code that generates the LFSR output is available on the CD in the code directory in the file lfsr.c.
Copyright © OnBarcode.com . All rights reserved.