At present, there are many popular USB turn serial lines on the market, and all kinds of chips have, common: FT232, CP2104, CH340 or PL2303, which better?
FT232 is the most commonly used, there are many versions, and there are many fakes. The fakes are not used, but the stability is poor, and occasionally bomb, the serial port is lost. The fakes of FT232 are subsequently distinguished and analyzed for true and false FT232. With the recent shortcomings, the price has also risen.
Specifications: https: //atta.szlcsc.com/upload/public/pdf/source/20130221/1457706592200.pdf
CP2102 / CP2104
This is my favorite solution. Some of our own USB turn serial ports will use this solution. The price is slightly high, of course, it is also the discussion of your own experience.
CH340G / CH340C
The earliest is from this USB turn serial chip to Nanjing Yi Heng (WCH), and there is currently some domestic MCUs and Bluetooth chips, network chips, peripheral chips, etc., the advantages are still very much, the price is cheap, the Chinese information province is going to find Translated, specifications, schematic, PCB, driver and other documents, extensive application, have problems, everyone will pass through you.
As a technician, it is still necessary to seek truth from facts. According to our own experience, there are too many products. It is unfriendly in the original entry, and the official website can find the corresponding difference. CH340G has strict requirements for load capacitance, mass production, or a certain proportion of bad prices.
Fortunately, the new generation of CH340C released, this CH340C and internal oscillator, work better.
Taiwan Wang Xia Technology, the chip price is moderate, but the price of USB serial modules sold online is much lower than this.
Specifications: http://www.prolific.com.tw/userfiles/files/ds.u PL2303HXD.U V1 U 4.pdf.
The US ATMEL chip is also an official solution of Arduino. Arduino uses the programmed 16U2 as a USB to serial port, not FTR232, which should be inexpensive than FT232 abroad. This solution is unwelcome, at least in some domestic PCB board design, did not see a peer to use this solution. Relatively, domestic prices are relatively high, and of course it may be short hair, and the knowledge is short.
Specifications: https: //atta.szlcsc.com/upload/public/pdf/source/20140724/1457707162350.pdf
According to more than 10 years of use of USB to serial port hardware engineering experience, from cost-effective, stability, technical difficulty, etc., it is recommended to choose this 2 chip: CP2102 / CP2104 and CH340C, as the main consideration of design.
Because the FT232 and PL2303 have already rotten the street, it is used in debugging, and it is unstable. Really on the product, or stability first, and atmega16u2, it will drop directly.