This course will cover how to transmit data between two relatively low speed devices. To accomplish this data transfer there are two choices, transfer data in parallel or in series. Here is an example of a parallel communications using a standard External Memory Interface (EMIF) as a reference. Some Silicon Labs MCUs provide this interface to external memory or devices. In this communications method, the address and data are sent as multiple wires. The number of pins required for the example shown above is 26 (address + data + control). By moving to a serial communication, the pin count to the IC can be reduced. Another aspect of parallel buses that becomes a limitation is the transmission speed. This really isn’t a concern when considering interfaces in the 8-bit MCU space; however, as speeds increase, the interfacing becomes much more of a challenge as the propagation delays between the data lines and their relationship with the clock sources is minimized.