Methods and apparatus to perform serial communications are disclosed. An example serial data transmitter includes: a clock signal generator to generate a digital clock signal; a clock signal controller to enable the clock signal generator; a line break signal generator to, in response to an expiration of a time period, trigger the transmission of a transmission line check frame; a data integrity check generator to generate error detection data corresponding to first data to be transmitted via the transmission port; a signal framer to: generate a first data frame having a preamble, second data, third data, the first data, the error detection data, and fourth data; and generate the transmission line check frame.