As one of the top 10 development boards under $10, the XR21B1411IL-0A-EB has a lot to offer.
An enhanced 1-CH Full-Speed USB UART evaluation board that operates from a programmable internal clock. Any baud rate up to 12 Mbps can be accurately generated.
Price: $5.73
At the core of the XR21B1411IL-0A-EB evaluation board is the XR21B1411 1-CH full speed UART chip, which can be powered directly from the 5 V supplied at VBUS. Also on the board is Exar’s programmable serial transceiver which can be programmed for RS-232 or RS-485/422 mode. The Exar LDO regulates the 5 V from VBUS to 3.3 V as is the required supply voltage of the SP336 and the VIO_REF of the XR21B1411. This evaluation board is great for portable applications such as battery-operated devices, dongles and portable appliances.