Dilshan R Jayakody’s Web Log

This is a simple sensor kit to drive 8 active or passive sensors and log its data into a remote Android application. This system also has an option to activate an external device(s) based on the specified threshold of sensor data. This sensor controller is mainly built around the Raspberry Pi Model 3 B+ and PIC16F877A MCU. PIC16F877A MCU is used to interface/select sensors and it's built-in 10bit multi-channel ADC is used to capture the analog signals from sensors. During the prototype stage following sensors are tested with this system: LM35 precision temperature sensor MQ7 Carbon Monoxide gas sensor Electret Microphone NSL-19M51 LDR HC-SR501 PIR sensor A3144 Hall effect sensor Apart from the above list this system can use to drive and capture most of the other analog/digital sensor signals such as current sensors, pressure sensors, chemical sensors, humidity sensors, etc. In this system, Android monitoring application is designed to connect with the sen...

Couple of months back we decided to create our own media server to store our MP3s and digital photographs. But it gets postpone several months due to unavailability of main-boards and other resources. Finally, after reviewing several prototypes we decided to build our media server using Banana Pi (BPI) and MiniDLNA . Before finalize BPI we checked several main-boards which including Raspberry Pi B+ , Orange Pi One and BeagleBone Black . Out of all above main-boards we choose BPI M1 because of its inbuilt SATA2.0 interface, Gigabit Ethernet port and availability in local market. Final view of DLNA media server setup. As an operating system we use Bananian Linux , which is Debian derivative for BPI platform. To sore all our content, we use Seagate 1TB SATA 3.5 inch hard disk drive. Bananian OS and other packages are loaded into 8GB SD card. To power both BPI and SATA disk drive we design PSU using LM2576-5.0 step-down switching regulator IC. Also during the prototyping sta...

In this post, we describe the fan controller which we designed for our 9U wall mount server cabinet. This fan controller is designed to drive a 12V DC cooler fan with pre-configured intervals or by monitoring the temperature of the server cabinet. The final version of the fan controller with DC brushless fan and 12V - 60W PSU. Core components of this fan controller are CD4060 binary counter, LM35 temperature sensor, and LM358 operational amplifier. In this design, CD4060 has used as long duration timer and it can be configured to trigger cooler fan from 1-minute and up to 4-hour. In this design, an LM35 temperature sensor is used to activate cooler fan in specified temperature. This sensor stage is useful to drive cooler fan when timer stage is in an inactive state. To control the cooler fan we use AP9971 dual N-channel power MOSFET transistor. We design this system to drive 12V cooler fans up to 2A of current. To test this controller we use commonly available 120mm × 120mm...