USB to serial converter devices exist at a cost of $4 - $8 online, with much lower pricing and longer delivery times if ordered from China. Search for "USB to UART TTL", including "5 pin" in the search. Make sure the specifications do not mention anything other than 3.3 volts.
Mac OS X users may need to install a device driver for their device. For example,
a device using a CP210X chip can download the [https://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx#mac CP210x USB to UART Bridge VCP Driver], which is available as <tt>/dev/tty.SLAB_USBtoUART</tt>.
==== Connecting to Serial ====