Dilshan R Jayakody’s Web Log

In the last couple of years, I tried several powered USB hubs to drive some development boards and USB peripherals. Most of the USB hubs which we can find in the local market are unreliable or not designed to drive more than 500mA of a load. After having a few bad experiences with powered USB hubs, I decided to build a USB hub by myself. I specifically design this hub to drive USB powered development boards and experimental peripherals. The core element of this USB hub is the " FE1.1s " USB 2.0 hub controller. " FE1.1s " is a low cost, 4-port, high-speed USB hub controller, and this chip can easily order by eBay or AliExpress . A prototype version of the USB hub. Apart from FE1.1s features, this USB hub has the following additional features: Switches to on/off and reset individual USB ports. Capability to provide a maximum of 3A of current from each USB port. Power using 9V to 15V DC voltage source. This USB hub uses PIC16F630 MCU and four units...

This is an easy to build "liquid level monitor" and "automatic control system". This control system is mainly based on Microchip’s PIC16F630 8bit MCU and few combinatorial logic ICs. This system is specifically design for industries where there is a requirement of maintaining a liquid level at a particular level. The level monitoring stage of this system can capable to sense up-to 8 liquid levels and its trigger point can be programmed at anytime by using its simple 2 button user-interface. This system is design to work with 12V (or maximum of 25V) DC power source and its sensor system is capable of sensing liquids with resistance of up-to 30k to 35k. To minimize the sensor noise and output instability, the control software is equipped with simple 20-tap FIR like filter system. The output stage of this system is design to work with 12V to 24V DC relays and it is recommended to use Tyco K10 series or similar kind of relay with this system. The trigger point o...

In this project we developed 4 inputs (Audio and Video), remote control operated video switch for general home use. This design is mainly based on Microchip PIC16F630 8bit MCU, 4052 differential 4 channel analog multiplexer, TSOP1838 infrared receiver module and 7447 BCD to seven segment decoder. With a given schematic and PCB design users can switch 4 different audio and video sources using compatible remote controller. Current version of this project is work only with most of Sony remote controllers (which based on Sony SIRC protocol) and it can be easily extend to Philips RC-5 protocol with some minor modifications of PIC16F630 software system. In this design we incorporate small single transistor video amplifier to its output stages to amplify the (chroma) part of video signal. Audio output stage of this system may not need any AF amplifier. (In the designing stages we notice some clipping of input signal in 4052 analog multiplexer, but it is not much noticeable in practical e...