1. EE4OI4 Engineering Design
Sequential Design and Hierarchy

2. Design problem
UP3: Design considered here is an 8-bit counter, with outputs displayed on LCD panel.
This is a sequential circuit since the value of output depends on the input and past behavior (state) both
UPcore functions are used for the design
UPcore functions are special hardware blocks designed to support the use of I/O features on the UP board (push buttons, seven segments, keyboard, mouse and video output).

3. Design problem
The counter should count up when one of the pushbuttons is pressed
The other pushbutton resets the counter
We use the function lpm_counter0 available in the Mega-functions library

6. Hierarchy
Complex designs are typically broken into smaller design units, which are easier to understand and implement
Smaller designs are interconnected to form the complex system
The overall design is a hierarchy of interconnected smaller design units.

9. Debouncing
A push button contains a metal spring and it makes several contacts before stability v t
Many of these pulses have enough amplitude to generate a clock pulse for the counter
counter
clk

10. Debouncing
For single-pole single-throw (SPST) push button: a time averaging filter
Time averaging
filter v t

11. Debouncing UPcore has a debouncing module
It uses a 4 bit shift register, clocked at 100Hz to do the filtering
If all four bits in the register are high (low) the output will be high (low)
A clock division module is used to reduce the 48 MHz UP3 system clock to 100 Hz.