Theory behind Android Arduino communication via Bluetooth

Bluetooth profile is a wireless communication interface that connects Bluetooth devices. The profiles define requirements for implementing of Bluetooth for various applications, such as, file transfer, wireless headset usage, etc. The following figure depicts different Bluetooth profiles and their usage. bluetooth_logo

Serial Port Profile (SPP) is probably the most popular profile used in smart phone based ubiquitous and home automation systems. SPP emulates RS-232 based communication protocols including all the control signals. It is based on ETSI 07, 10 and the RFCOMM protocol (Read more).

RFCOMM is a simple set of transport protocol used for serial port emulation. It supports up to sixty emulated serial links on a single Bluetooth enable device. The emulated serial ports can again multiplexed through single point-to-point connection or point-to-multipoint connection piconet through several Asynchronous Connection-Oriented Logical transport (ACL) links. The flow control mechanism of Bluetooth is more complex than the physical serial port because it has to pass through several layers of Bluetooth stacks. Bluetooth link introduces a delays as compared to wired serial port, thus it degrades the flow control mechanism.

VT-100 Terminal Emulator: A VT-100 terminal emulator is a program that emulates a video terminal on an external and separate display unit. Many smart phone platforms support VT-100/ANSI terminal emulator which can be used for connecting serial Bluetooth devices working with Serial Port Profile (SPP). Bluetooth terminal emulator works with a Bluetooth serial adapter and it can display serial data flowing in and out of smart phone. In a smart phone operated electronic system, Bluetooth emulator can be used to see the data processed by a microcontroller. It can also be used as an input unit for giving commands to the microcontroller.

Bluetooth serial port profile (SPP), RFCOMM protocol and terminal emulator program work at the core of Bluetooth based smart phone applications that are used for operating electronic systems. The same logic also works for computer operated systems. A system made for smart phone can also be operated using a computer.

For Android- Arduino communication, you can use a general Bluetooth adapter or a BlueSMiRF module from Sparkfun.

Using the TLP250 Isolated MOSFET Driver Explanation and Example Circuits

I’ve already shown how to drive an N-channel MOSFET (or even an IGBT) in both high-side and low-side configurations in a multitude of ways. I’ve also explained the principles of driving the MOSFETs in these configurations. The dedicated drivers I’ve shown so far are the TC427 and IR2110. Some people have requested me to write up on MOSFET drive using the very popular TLP250. And I’ll explain that here. The TLP250, like any driver, has an input stage, an output stage and a power supply connection. What’s special about the TLP250 is that the TLP250 is an optically isolated driver, meaning that the input and output are “optically isolated”. The isolation is optical – the input stage is an LED and the receiving output stage is light sensitive (think “photodetector”). Before delving any further, let’s look at the pin configuration and the truth table. Fig. 1 - TLP250 Pin Configuration Fig. 2 - TLP250 Truth Table Fig. 1 clearly shows the input LED side and the receiving photodetector as well...

OP AMP INTEGRATOR CALCULATOR

Enter the Input Voltage,Vin: Volts Enter the Frequency, f: Hertz Enter the Input Resistance, Rin: Ohms Enter the Value of Capacitor, C: Farads Output Voltage, Vout: Volts OP AMP based Integrator Tutorial and Design

Block diagram of AM transmitter and receiver with explanation

Block diagram of AM transmitter and receiver with explanation AM Transmitter : Transmitters that transmit AM signals are known as AM transmitters. These transmitters are used in medium wave (MW) and short wave (SW) frequency bands for AM broadcast. The MW band has frequencies between 550 KHz and 1650 KHz, and the SW band has frequencies ranging from 3 MHz to 30 MHz. The two types of AM transmitters that are used based on their transmitting powers are: · High Level · Low Level High level transmitters use high level modulation, and low level transmitters use low level modulation. The choice between the two modulation schemes depends on the transmitting power of the AM transmitter. In broadcast transmitters, where the transmitting power may be of the order of kilowatts, high level modulation is employed. In low power transmitters, where only a few watts of transmitting power are required , low...

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