Areptone Electronic Products
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Technical Article By Mr. Adeeb Raza
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Technical Article By Mr. Adeeb Raza |
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..............USB INTERFACE FOR 1-WIRE DEVICE Nowadays the name microprocessor is a very common in the field of automation and engineering. The microprocessor-based system performs their function very accurately, very fast in low cost. Therefor the microprocessor is involving in every field of engineering to make human life easy and comfortable. We are all aware that the Computer is an electronic machine based on very advance Micro-processes and the combination of very sophisticated electronic circuits for performing the difficult task in less time. The computerization is also taking place in the field of engineering and automation for home, office and industry. This is all possible because of very fast development in electronics technology, integration and the invention of micro-processes technique. The computer as office equipment is also very common and people are using the computer in DTP, Engineering Designing, Software development, Internet, Banking, Communication, Networking and many more etc. The computer networking provided the facility to share data, file, Internet, printer and other links with each other. The machine is one and the uses are more because the computer is a machine, which involves hardware and software both and configure as per the individual work and requirement. IBM has set the Computer international standard norms. As per the IBM standard every computer has the LPT-1 port for printer attachment for printing with computer and COM-1, COM-2 ports are for attachment of other external devices like Mouse, Modem, LAN etc. Beside this extra ISA/PCI slot has also been provided on every computer for attachment extra cards. The Internal modem, Internal LAN, Sound card, TV Tuner card, Extra I/O card can be install on the same slot for other purpose. The computer case is the main part where the power supply, mother board, floppy disk drive, Hard disk drive, CD-ROM drive, VDU socket, Key board Socket, LPT-1 Parallel port, COM-1, COM-2 Serial ports, etc are fitted to form a Central Processing Unit (CPU). The motherboard is hart of the computer where Microprocessor Socket is provided for Fixing Microprocessor, ROM (BIOS) socket, RAM socket, Key board controller circuit, IDE circuit, VDU circuit, Slots etc. other control circuit are fabricated on the same board. All these section and card use port address or I/O address to interface with the Microprocessor. In this type of circuit and card the processor communicates with these cards by writing into or reading from these port address. The I/O port number 000h to 0FFh are reserved for motherboard devices and number 100h onwards can be used for the expansion cards. In addition to LPT-1, COM-1, COM-2 ports an USB Port (Universal Serial Bus) is beginning to be used more frequently for connecting peripherals to PCs.The USB port does have several advantages compared to the serial port/ Parallel port. The USB port contains only four wires while serial port contain nine wires and parallel port 25 wires. To add serial device is more complex every device required its own serial port and their power supplies. While this is fact that several devices can be connected to a single USB port through a USB HUB which is a very beg improvement. It is also that many peripherals can draw their supply from the USB Port or hub. The USB devices can be plugged into the running condition of PC. The operating system on the computer detects this immediately and self installs the appropriate driver for the same device. The USB connector is shown in Fig-1 & Fig-2. Pin1 Positive, Pin 2 –D, Pin 3 +D and Pin 4 negative ground.
This project is also based on USB port and converts USB port into one wire bus interface. The hart of the project is an IC-DS2490 in 24-pin package manufactured by Dallas Semiconductor for converting USB port to 1-Wire bus system.The complete circuit diagram is given in Fig-2. And the functional block diagram and pin assignment of DS 2490 is shown in Fig-3. To run this project you need the device driver for DS2490. The Device Driver for Windows 32-bit V3.22 file is an executable file. The name of file is TM322_32.EXE. This is a self-extract file and can be down load free from Internet. The website of manufacturer M/s Maxim/Dallas Semiconductor is http://www.maxim-ic.com/ or http://www.ibutton.com/software/tmex/index.html or http://www.maxim-ic.com/ where you will find the Timex with ibutton Viewer with drivers and 1-wire software Developer’s Kit (SDK). For fabrication of this project you should also know the handling and soldering of surface mounting technique for components on PCB. The device one wire bus from M/s Dallas Semiconductor is very useful for making a small computer network with combination of switches, sensors and actuators etc. Circuit DescriptionThe circuit is very simple and self-explanatory. This interface circuit builds around an IC-DS2490 and the software that easily communicate between USB port of computer and 1-wire device. See Fig-2 circuit diagram of interface you will find that one side of DS2490 is USB and connecting pin no 2 and 3 with pin no 7 (-D) and 8 (+) with series resistance of 33 ohm respectively as input. Ready made EMI filter L1 & L2 or two resistances of 10 ohm with capacitor 33 pf has fixed on power supply pin no.1 & 4 of USB as EMI, high frequency suppression. The IC- DS2490 take care of total function from USB 4-wire conversion to 1-Wire interface system. At output pin no. 10 two diodes BAT54S and one special zener diode IC-DS9503 has been provided as protection circuit. IC 3V3 as regulator on pin no.5 (VB). One can use any other 3-pin regulator IC in place of LF33CV. The VD voltage at pin no. 24 will always be higher than VB voltage. |
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Down load and Install TM322_32.EXE on you PC, you will get three other files in a directory name Dallas Semiconductor in Windows, Program Files that are (1) SETPRT32.EXE, (2) IBVIEW32.EXE & (3) IBVIEW32.HLP. When you will run SETPRT32.EXE file you will get the screen for 1-wire Net port Selection. Select PC port by click on DS9490 as USB this will automatically detect and install the required driver on your PC.
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Next you should run the iButton Viewer application from the start menu à programàIButtion-TMEXà click on Icon name iButton Viewer32 see following Fig. The iButton Viewer is a Windows program for communicating with iButtons and other 1-Wire Net compatible 1-Wire devices. It integrates most of the iButton-TMEX utilities in a single, user-friendly piece of software. Now you can connect one wire device through this interface to your computer to run and control the system in case of any problem refer to help file.
IButton information: http://www.ibutton.com/
Dallas Semiconductor information: http://www.maxim-ic.com/
Areptone Electronic Products: http://lucknow.sancharnet.in/adeebraza/areptone/drivers.html
The Following Files are attached here with for your ready use
1. TM322.ZIP ------> Driver Installer Files
2. 1-WIRE SDK VER 400 BETA .EXE ------> Software Development Kit
3. DS2490.JPG ------> Circuit diagrams
