What is it?

The CH340G is an inexpensive USB serial adapter chip - similar to the better known FTDI FT232 chip. Programming an Arduino Pro Mini, a breadboard Arduino, or one of my ATtiny boards requires a USB serial adapter with a 6-pin header with GND, Vcc, Tx, Rx, and DTR. This has traditionally taken the form of an "FTDI" adapter using the FT232 chip; these are still widely available, though they are significantly more expensive than CH340G-based modules. Although CH340G-based USB serial adapters are readily available on eBay for insanely low prices, those do not bring the DTR pin out - and most of them plug directly into the USB port, necessitating an extension cable.

Clearly, better could be done.

New and improved version here

What makes it special?

• 500mA self-resetting PTC fuse (other current limits available)
• 6-pin programming header for Arduino Pro Mini et. al.
• Mini-USB connector (I have not been satisfied with the durability of Micro-USB)
• Tx and Rx LEDs
• No power LED - these just waste power
• Available in 3.3v and 5v versions
• Self-resetting PTC fuse, 500mA or 250mA
• 3.3v version uses a REAL VOLTAGE REGULATOR, not two cheap signal diodes in series like most USB serial adapters (which results in nominally 3.6v, but lower under load, since they don't even use decent diodes).
• Assembled in the USA (using parts imported from China).

This board is sold ASSEMBLED as shown, WITHOUT pin header. Use with female pin header (for direct connection to most boards), male pin header (for use with jumper cables or breadboard), or other connector as dictated by your needs.

Bare board available here