Ethan Zonca of Protofusion writes:
While developing the Luma RS485-networked LED driver we discovered a need for a small and inexpensive USB to RS485 adapter. We designed an adapter with a FTDI basic UART chip (FT230XS) and an inexpensive TI differential receiver (SN75176). Our small selection of parts brings the cost down to just over $5 for one adapter.
Open hardware USB to RS485 adapter - [Link]
Integrated circuit FT232R is becoming legendary and we bring you another example of FTDI USB chips usage.
In praxis we often face a requirement to communicate with devices, which have serial ports RS232, RS422 and RS485. As many devices – mainly notebooks, already usually don´t have these ports, it is necessary to use a converter to convert serial port to USB.
Company ComErgon, s.r.o. is long-term dedicated to development and production of such converters. ComErgon has in its offer models for RS232, RS422 a RS485 interfaces. USB to RS422 and RS485 converters are produced with a 1kV galvanic isolation, as lines on the RS422 and RS485 side can be lead even on long distances and an eventual overvoltage could be able to damage end devices. Version RS232-USB is available with galvanic isolation but also without isolation.
More detailed information and technical specification of these converters can be found at website of company ComErgon.
Company ComErgon focuses on development and production of converters for RS232, RS422, RS485, RS422/RS485 repeaters, serial to Ethernet interface modules, GPRS, Fiber Optic, 433MHz, current loop and other.
Customer solution: Trouble-free RS232, RS422, RS485 to USB conversion - [Link]
3in1 universal converter. Based on FTDI 232R chip seen as normal COM port, and two serial converters MAX232 and MAX485. Allow to be used as RS232, RS485, or UAR TTL converter. Connections parameters can be set through the system, as in normal COM port. Supported speeds: 110 to 921600bps.
3in1 converter – USB to RS232, RS485, UART - [Link]
This project is one of many I have undertaken to control my house using a set of rules, a web interface, a logger and many more components. This project is a light dimmer which has multiple control interfaces such an RS485 network, an infrared remote control, a proximity touch slider or touch sensor.
Network Light Dimmer – [Link]
Is the evolution of the binary clock and allows planning time ON and time OFF for a relay. To keep consumption low a bistable relay was used, ’cause it needs power only when the status changes. Through the two buttons you can set time ON, time OFF and the current time. To drive the single coil bistable relay I used an RS485 driver, because it can provide 60mA output.
Daily Timer with binary display - [Link]
Today, although the wireless technology grows very fast, the long distance funicular communication still keeps its popularity. The reason is obvious that cost and complexity is high at the wireless communication.
RS232 is probably one of the most used, easy to develop and easy to apply communication protocol. We generally encounter to this standard at the MCU applications. But it has some restrictions. It allows us to use maximum 15 meters cable. Good wiring, low baud rates and less noisy mediums may allow us to exceed this limit a little more. The main problem here , when the distance increases, the noise at the common ground line also increases. Another issue, RS232 allows only two devices to communicate reciprocally. More than two devices can not communicate at this line and we need another solution for this situation.
RS485 is the standard that solves this problems. The main difference is, RS485 transfers the data depending on the potential difference between the two communication wires. The polarity defines the logic state of the signal. You can transfer data up to 1220 meters far away and with a rate up to 10 Mbs.
RS232 – RS485 Converter with Automatic RX – TX Control – [Link]
This 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.
RS485 to RS232 converter - [Link]
If you want to run simple webserver on embedded platform and have plenty of controllable interfaces you should consider on building or purchasing etherrape – AVR enabled Ethernet board.
This fancy board almost doesn’t have SMD elements and can be soldered by anyone with moderate soldering skills. Despite the fact that Atmega644 is interfaced with ENC28J60 Stand-alone Ethernet Controller with SPI connectivity, it also has a list of other valuable built in interfaces:
- Ethernet and TCP/IP
- Simple webserver;
- Linux command line tool;
- RS485/422 (half- /fullduplex);
- Dallas 1wire bus;
- Infra-red Receiver and Transmitter for RC5 Codec;
- MCA-25 Handy-Camera with VGA resolution can be attached (approx 10 Euro on ebay), not yet supported by firmware;
- 2MB Data-Flash memory;
Lots of great thing can be done with all these board abilities including webserver, Ethernet converter to RS232, RS485, 1-wire, infra-red, I2C, SPI interfaces. So it can serve as remotely controlled platform or data acquisition board where all readings can be seen on web screen. Project files and firmware can be downloaded from project page. [via]
AVR based multipurpose ethernet board - [Link]
It is always good to have handy microcontroller development board where you could test, debug embedded programs. Generally speaking development boards have to be universal and also convenient for interfacing. So usually when people make these tings usually build in some periphery to be ready to use like RS232 interface, MMC/SD slots.
So here is one development board with ATmega128 microcontroller which is small but has lots of functionality ready to go like RS232, RS485, ISP, JTAG, MMC/SD connectors. Also it has 62kB of external RAM – so you can run really serious programs without wary. Don’t forget other interfaces like I/O, I2C, SPI, and RTC that are positioned in two additional pin-headers. [via]
Atmega128 development board with MMC/SD slot - [Link]