VHDL Stopwatch with Split A presentation by Scott Conaton and Colin Dolcetti

Project Objectives Build and implement a fully functional stopwatch using VHDL programming techniques developed in class. Demonstrate the use of the stopwatch to the class as a whole.

Design We developed several new modules to utilize in the main program Time_Gen: a time value generator, which outputs the time elapsed since the input, clkin has been set to 1. BTNx: toggles the value of its output whenever it recieves a clock pulse.

Time_gen This module consists of four modified counters, tenscnt, onescnt, tenthcnt, and hunscnt. The output of each of these counters is its corresponding time digit. The counters each receive the clock pulse and delay it the appropriate time

q1q2q3 tenscnt q4 clk Time_gen clkin clr hunscnt clkin clr tenthcnt clkin clr onescnt clkin clr

Main Program The main program takes the time value output by time_gen and sends it to the data registers T and N. The display register, DI, loads the value in N into the display module, which then outputs the time value to the 7-segment displays

FinalMain N2 N T clr clk clk1 clk2 clkin diload BTN(1) BTN(2) Time_gen display clk A(3:0)AtoG(6:0) Q T clr clk tload N clr clk tload DI clr clktload BTN? debounce

dig7seg A(4:1) AtoG(6:0) display dig4(3:0) anode "1111" dig1 dig4 dig3dig2 clk4 dig3(3:0)dig2(3:0)dig1(3:0) osc_4k

Main Program Controls When either button is pressed, its value is sent through a debounce to reduce it to a short clock pulse. The pulse then travels through the BTNx module which, if BTN(1) is pressed, toggles the clkin signal, and if BTN(2) is pressed, toggles the diload signal.

Effect of clkin and diload Clkin and diload are initially set to 0 and 1 which stops time_gen, and allows the value in N to be loaded into DI and displayed. When clkin goes to 1, time_gen begins to count and the current value is output to the displays. When diload goes to 0, DI no longer loads any new values from N.

Effects (Cont.) At this point N still updates from time_gen every pulse, but only the last value in DI is displayed, until BTN(2) is pressed again, resetting diload to 1. This is how we created the split effect.

Demonstration of Stopwatch We will now demonstrated the final implementation of our stopwatch program Please hold your questions until the demo has finished.