Nabil Tewolde build a bluetooth OBD-II adapter. He writes:
The board is basically the reference schematic for the STN1110, which converts many OBD-II physical layers into RS232. The bottom of the board has a bluetooth module from Deal Extreme. The plan is to connect a smartphone or tablet to the device and log data.
Bluetooth OBD-II Adapter - [Link]
Andrianakis Haris describes in detail his B.Sc Thesis:
PLC (Power Line Communication) is the technology that allows data transmission over the existing Power Line network. Power Line can be the home power network or the national electricity transmission grid. The data that can be transferred is as diverse as its speed. With speeds of nearly 200Mbps, video transmission, voice, data and any other services can be transmitted successfully.
On this article i’m going to describe in detail my B.Sc Thesis in department of Electronic Computer Systems Engineer at Technological Education Institute of Piraeus, October of 2012 in Greece.
The project includes the design of two modules (transmitter – receiver) implementing a serial communication over the Mains connecting a remote large display to a weighing machine.
Power Line Communication - [Link]
The PCA9508 is a CMOS integrated circuit that supports hot-swap with zero offset and provides level shifting between low voltage (down to 0.9 V) and higher voltage (2.7 V to 5.5 V) for I2C-bus or SMBus applications. While retaining all the operating modes and features of the I2C-bus system during the level shifts, it also permits extension of the I2C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, thus enabling two buses of 400 pF. Using the PCA9508 enables the system designer to isolate two halves of a bus for both voltage and capacitance, and perform hot-swap and voltage level translation. Furthermore, the dual supply pins can be powered up in any sequence; when any of the supply pins are unpowered, the 5 V tolerant I/O are high-impedance.
PCA9508 has B-side and A-side bus drivers. The 2.7 V to 5.5 V bus B-side drivers behave much like the drivers on the PCA9515A device, while the adjustable voltage bus A side drivers drive more current and incur no static offset voltage. This results in a LOW on the B-side translating into a nearly 0 V LOW on the A side.
The hot swap feature allows an I/O card to be inserted into a live backplane without corrupting the data and clock buses. Control circuitry prevents the backplane from being connected to the card until a stop command or bus idle occurs on the backplane without bus contention on the card. Zero offset output voltage allows multiple PCA9508s to be put in series and still maintains an excellent noise margin.
- PCA9508D CMOS integrated circuit (3 units)
- BUS Master
- Slave 400kHz (3 units)
- 10kΩ Resistor (6 units)
- Ground Source
Hot swap level translating I2C repeater - [Link]
ajoyraman @ instructables.com writes:
PC sound cards form a readily available Signal Generator for testing electronic circuits. The utility of these signal generators is limited because the outputs are AC coupled and limited to ±2V.
Taking advantage of the two channels provided by the sound card this Instructable shows a scheme which uses one channel to output the Sin/Square/Triangle waveform with a fixed gain, while setting up a 441 Hz PWM square wave on the second channel. This PWM waveform is converted to ±8V averaged and summed with the first channel to provide a DC offset controllable by the duty-cycle setting.
PC Sound Card Signal Generator Interface - [Link]
DigiPot is a digital potentiometer using a rotary encoder as input along with a 7 segment display that show the current pot value.
The “potentiometer” is actually a rotary encoder (TW-700198) connected to a microcontroller that reads the signal from it and convert it to a value that is displayed on 7-segment displays. The value also is sent via i2c/spi/serial/usb to the host. Also 3 LED and included for status indication.
DigiPot – Rotary Encoder Potentiometer - [Link]
by Publitek European Editors
This article looks at the latest touchscreen sensor technologies and the wide range of interfaces that the different technologies use. It also evaluates the different approaches for interfacing such sensors for human interfaces from three, four and five wire to USB, covering sensors and interfaces from Atmel, 3M, IR Touch Systems, and NKK Switches. Resistive 4- and 5-wire touch sensors are the most popular and most common touchscreen technologies with about 75% market share, mainly due to their low costs and simple interface electronics. The high volume of these screens requires a low-cost reliable interface, often with a low-power element. This can be provided through a range of analog features combined with low-power modes for portable, battery-powered applications.
Evaluating Different Approaches for Interfacing Touchscreens - [Link]
Brian Schmalz writes:
The UBW board is a small board that contains a Microchip PIC USB-capable microcontroller, headers to bring out all of the PICs signal lines (to a breadboard for example), only costs about $15-$20 to build and is powered from the USB connection.
UBW – USB Bit Whacker- inexpensive, simple input/output USB device - [Link]
This app note describes the common IC interface protocols like I2C, SPI, and GPIO. Also some problems covered with these interfaces that turn happy faces to sad. [via]
How can an interface change a happy face to a sad face? Engineers have happy faces when an interface works properly. Sad faces indicate failure somewhere. Because interfaces between microprocessors and ICs are simple—even easy—they are often ignored until interface failure causes sad faces all around. In this article, we discuss a common SPI error that can be almost impossible to find in a large system. Links to interface tutorial information are provided for complete information. Noise as a system issue and ICs to minimize its effects are also described.
Common IC interface problems - [Link]
The LTM2883 is a 6-channel SPI/Digital or I2C digital μModule isolator with triple rail regulated power for 3.3V and 5V systems. In industrial systems applications, ground potentials can vary widely, often exceeding the tolerable range, which can interrupt communications or even destroy components. The LTM2883 breaks ground loops by electrically separating communications signals, isolating the logic level interface on each side of an internal inductive isolation barrier that withstands a very large common-mode voltage range up to 2,500VRMS. The LTM2883′s low EMI isolated DC-DC converter powers the communications interface and provides adjustable 5V, +12.5V, and -12.5V supply outputs, ideal for powering data converters in data acquisition systems. With 2,500VRMS of galvanic isolation, onboard secondary power and a communications interface operating at up to 20Mbps, the LTM2883 requires no external components and provides a simple μModule solution for isolated data communications.
LTM2883 – SPI/Digital or I2C μModule Isolator with Adjustable Regulated Power - [Link]
This table provides top-level characteristics for serial interface standards by which two or more digital devices can be connected for communication. Design engineers can use the table to compare interface options for their application based on the design constraints like number of signal lines, network size, speed, distance, noise immunity, fault tolerance and reliability.
Serial Data Communication Protocols Comparizon - [Link]