Keypad HDL encoder signal naming In the keypad encoder design, a signal or bit array often named “ts” is used to control tri-state enables for shared bus or column/row drivers.

Introduction / Context: In keypad scanners and other bus-shared designs, HDL commonly uses tri-state enables to allow one source at a time to drive a shared line (such as a row driver or a bidirectional port). A control vector like “ts” (tri-state) is a conventional name for the enable bits, where each bit turns a driver on or off.

Given Data / Assumptions:

• Multiple lines share a common resource and must not drive simultaneously.
• HDL supports tri-state ports or, in FPGA flows, infers multiplexers for internal busses and uses tri-state only at I/O pins.
• “ts” is treated as an enable mask: ts[i] = 1 enables driver i.

Concept / Approach: During scanning, exactly one row driver is enabled while others are set to high-impedance (Z). The “ts” array represents these enables. Even if the synthesis tool replaces internal tri-states with multiplexing, the naming and intent remain: control which source is actively driving and which are Z.

Step-by-Step Solution:

Verification / Alternative check: Waveforms should show only the selected line actively driven; others stay at Z or are not selected in the multiplexer model.

Why Other Options Are Wrong: “Incorrect” conflicts with common naming conventions and usage. “Represents test sequence only” misinterprets the abbreviation. “Only used for analog multiplexers” is unrelated to digital tri-state control.

Common Pitfalls: Driving multiple lines simultaneously; forgetting that many FPGAs disallow internal Z—requiring mux logic internally and Z only at pins.

Final Answer: Correct