Accepting credit cards can be expensive. If you have a permanent selling location with a phone line or data connection you can use a standard credit card terminal. Or if you are on the go you can use a mobile credit card terminal just like the pizza guy when he comes to your door. With both of these options you need to pay for the equipment and pay some steep monthly fees. Adafruit Industries which primarily an online kit business doesn’t run a permanent retail outlet so there’s no need for a physical credit card machine unless they are out at an event.
There are lots of virtual credit card terminals which let you just type in the data on a web page using a secure connection. These are perfect for low volume occasional transactions since the entry system is a bit cumbersome, you need to enter the customers name, credit card number and expiration date. If any of these are off the transaction will obviously not go through.
To speed things up Limor Fried from Adafruit Industries rigged up a neat DIY Credit Card System. A low level credit card reader was connected to a ATmega32u4 on a dev board called the Teensy. The microcontroller watches the credit card reader data lines, when a credit card is swiped the microcontroller captures all of the information. The Teensy then emulates a USB keyboard and maneuvers around the credit card web form entering all the data from the credit card. Say goodbye to mis-typed names and numbers!
