If you need to establish a communication between your microcontroller unit and a computer, USB-to-UART converters provide a reasonable solution. Some microcontrollers have USB hardware on board, but the modules allow one to use devices which lack the USB hardware. Of course, such modules can be purchased fully assembled from various distributors. However, if you do not mind to etch PCBs by yourself, your can get such a module for a fraction of price.
I checked 3 of them based on Microchip MCP2200 chip, FTDI FT232RL chip, and Silicon Labs CP2102 chip. The schematics are based on the ones from their data-sheets, I put them here for convenience.
| MCP2200 | FT232RL | CP2102 | ||
Each of the modules must be configured before the first use. For this each of the above mentioned manufacturers provides software and drivers to download. The configuration process is pretty well described there, so I emphasize on hardware issues.
Each of the modules is assembled on a single-side PCB, the first two have a mini-USB connector, the CP2102 has a USB connector of type B installed. CP2102 was the first one I tried, so I tried to fix the design flows I made in the other two modules. First, I find it more convenient to use a mini-USB connector. Second, make sure to provide receiver and transmitter LEDs which allow to check the data traffic visually. This might be important as you are developing your software. And third (but not last) - make sure to forward RTS and CTS signals outside the module. This way one can use hardware controlled communication which speeds up the communication and makes it more reliable. These features are missing on my CP2102 board, but I am sure you can easily modify it, if needed. The supplied boards were designed by using Eagle software.
| Assembled modules |
... a tough question. Each of them works flawlessly and configuration is just a breeze. So, from this viewpoint I cannot distinguish them. However, CP2102 is only manufactured in a fine-pitch QFN package which is more difficult to solder. Compared to this, MCP2200 is the easiest to solder, as it is available in SOIC and TSSOP packages. However, it seems to me that it is only intended for a 5V operation. The two others can be externally powered from 3.3-5V which makes them more flexible.
Last modified:Mon, Jan 23, 2023.