Editing Transistor–transistor logic (section)

=== Serial signaling ===
'''TTL serial''' refers to [[single-ended signaling|single-ended]] [[serial communication]] using raw transistor voltage levels: "low" for 0 and "high" for 1.<ref>{{cite book|title=Signal and Power Integrity in Digital Systems: TTL, CMOS, and BiCMOS|year=1996|isbn=0070087342|url=https://books.google.com/books?id=6yRTAAAAMAAJ&q=single-ended+TTL-+or+CMOS-level+communication|page=200|last1=Buchanan|first1=James Edgar|publisher=McGraw-Hill }}</ref> [[Universal asynchronous receiver-transmitter|UART]] over TTL serial is a common debug interface for embedded devices. Handheld devices such as graphing calculators and {{nowrap|[[NMEA 0183]]-compliant}} [[Global Positioning System|GPS]] receivers and [[fishfinder]]s also commonly use UART with TTL. TTL serial is only a ''de facto'' standard: there are no strict electrical guidelines. Driver&ndash;receiver modules interface between TTL and longer-range serial standards: one example is the [[MAX232]], which converts from and to [[RS-232]].<ref>{{cite web |title=RS-232 vs. TTL Serial Communication - SparkFun Electronics |url=https://www.sparkfun.com/tutorials/215 |website=www.sparkfun.com}}</ref>

[[Differential TTL]] is TTL serial carried over a [[Differential signalling|differential pair]] with complement levels, providing much enhanced noise tolerance. Both [[RS-422]] and [[RS-485]] signals can be produced using TTL levels.<ref>{{cite web |title=B&B Electronics - Polarities for Differential Pair Signals (RS-422 and RS-485) |url=https://www.bb-elec.com/Learning-Center/All-White-Papers/Serial/%E2%80%A2-Polarities-for-Differential-Pair-Signals-%28RS-422.aspx |website=www.bb-elec.com}}</ref>

[[ccTalk]] is based on TTL voltage levels.