Dilshan R Jayakody’s Web Log

Universal Serial Bus (USB) allows peripherals and computers to interconnect using standard protocol and provide plug and play feature to the devices. At the moment there are 2 specifications available for USB they are, USB 1.1 : In this specification data transfer rate is 12Mbps and 1.5Mbps. USB 2.0 : Support data transfer rate up to 480Mbps. Both these specifications support up to 127 devices and support for hot swapping (no need to power down to remove or connect the devices). In USB devices are categorized as a classes and each class represent the functionality that target device can provided to the host device. For example: AUDIO : Audio and related systems HID : Human Interface Devices. (E.g: Keyboard, Mouse, etc) POWER: Devices related with the power such as UPS systems. IrDA: Infrared devices. There are 4 types of transfers take place over USB, Control transfer : Used to configure the bus and devices on the bus. Bulk transfer : Move data asynchronously over USB. Isochron...

I’m trying Delphi for PHP 2.0 in few days back and I'm get very frustrated about it because of its pour implementation and technologies. Some key failures in Delphi for PHP 2.0 are, - IDE is very buggy and most of the times it produces "Access Violation" errors and IDE get confused. (In my computer Delphi 7 tries to debug it.) - Help is very pour and incomplete. - JavaScript and PHP integration is very complex and buggy. Most of the time JavaScript codes may not work in client side and it is heavily depends on the web browser. - Some times it is necessary to deploy entire "VCL" directory to the web server otherwise some of the VCL components produces invalid outputs. (specially RichEdit and TrackBar components) - MySQL integration is pour and buggy. - Build-in Apache web server crash several times and because of that reason we may not be able to debug/run web application using IDE. - Some times XML file (xml.php) generated by Form Designer may not compatible wit...

According to my experiences USB devices are bit complicated to design and writing software (drivers and support applications) for USB devices are time consuming and complex process. Most recommended (and easiest) method to design hardware interface for USB port is using Future Device Technologies FT245 or FT232 chips. At the moment both these chips support for USB 2.0 and have excellent set of APIs. To test the performance of this device I implement some experimental version of PC oscilloscope using FT245 USB Interface, AD7575 ADC, LF347 Op-amp, 4069 Hex Inverter and array of AM7205 FIFOs. Application program is design using Delphi 7 and it is totally based on FTDI Delphi APIs. This test system is worked perfectly in Windows XP and Windows 2003 systems during my test runs and produce excellent results. I choose FT245 for this design because it has 8 parallel input interfaces and this is perfectly matched with AD7575 ADC. (AD7575 also have 8 parallel outputs) I use 2705 FIFOs to captur...