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My Engineering Zone

Projects & Notes

Embedded Systems — Traffic Light Controller

Finite State Machine (FSM) with debounce logic, built on STM32 using HAL. Timing via SysTick, states: RED → RED_AMBER → GREEN → AMBER.

// Pseudocode
state = RED
loop:
  output_lights(state)
  delay(T[state])
  state = next[state]

Signals — FIR Low‑Pass Filter

Windowed‑sinc filter, Hamming window, N = 51 taps. Great for smoothing sensor noise.

for n in range(N):
  h[n] = sinc(2*fc*(n-M)) * (0.54 - 0.46*cos(2*pi*n/N))

Algorithms — Dijkstra in 12 Lines

def dijkstra(g, s):
  import heapq
  dist = {v: float('inf') for v in g}; dist[s]=0
  pq=[(0,s)]
  while pq:
    d,u = heapq.heappop(pq)
    if d!=dist[u]: continue
    for v,w in g[u]:
      nd=d+w
      if nd