Cheap AVR I2C Tiny Usb

I2c-tiny-usb made to provide a cheap generic i2c interface to be attached to the usb. It could be as simple and cheap printer port to i2c adapters. A USB solution has several advantages such as the built-in power supply and no cpu intense bitbanging is required on the host side. This USB solution even requires less parts than some printer port solutions. Although i2c-tiny-usb was developed under and for Linux but it also works under Windows and MacOS X.

The hardware the i2c-tiny-usb interface which is designed by Till Harbaumof consists of the Atmel AVR ATtiny45 CPU, a cheap and easy to obtain microcontroller with 4 KBytes flash (of which ~2k are used in this application) and 256 Bytes RAM. And few other parts surrounded the processor.

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Source code, schematic and documentation

tag : USB project, i2c adapter, printer port adapter, avr project (src)

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RS485 to RS232 Converter

Converter is intended to use with PC computer to communicate with ROV using 2 wires in half duplex mode. Send/receive mode is selected by RTS signal. The converter was designed to be as simple as possible, so it has no some features that can be found in commercial grade products (e.g. galvanic separation).

Popular chip MAX232 is used to convert RS232 signals from/to TTL level. MAX485 converts TTL level signals to RS485 standard. RTS line is used to change transmission mode of MAX485. RTS signal is first converted to TTL level by MAX232 then connected to DE and RE/ pins. 2 LED are used to indicate current state of the interface.

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RS485_to_RS232_Converter_Schematic.pdf
RS485_to_RS232_Converter_Elements.pdf
RS485_to_RS232_Converter_BOM.pdf
RS485_to_RS232_Converter_PCB.pdf

Electronic Circuit project, RS485 to RS232 converter, Digital circuit (src)

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