CH340G – cheap USB to serial alternative

In many microcontroller projects you might want to add an USB interface which is based on USB to serial converter. There are many chips available that does this job well. Most popular is FT232R or similar which is quite expensive and in some projects it can be too pricy. If you look around, you will find that there are tons of alternatives that cost cents. Ian suggests to take a look at CH340G chip which costs as little as 40 cents. Of course it comes from China market. He purchases several of these and built eagle part so everyone could easily include in project. Since datasheet of this chip is scarce, he’s done the hard work by finding pin-outs and drawing typical schematics for 5V and 3.3V circuits. Continue reading

Easy and cheap way to add USB to AVR project

Actually there is not much about microcontrollers but more about building cheap and dirty USB to TTL converter so it could be used with any microcontroller with USART interface.  You can always find chips that will do the job, but usually they are pretty expensive and may require special drivers. So it seems there is another solution – buy cheap USB to RS232 cable and you will find that it isn’t RS232 compliant – only 0/5V levels and only can handle -12/+12V.  So 0/5V is what you need. A little tweak to plug PCB and you will have cheap USB that works. On the page also you’ll a proof with Atmega microcontroller that uses simple uart_putc() and uart_getc() commands. [via] Continue reading