Components - RicoJia/notes GitHub Wiki

• Illustration
• Key points: the waveform is: positive half, negative half.

• Basics
  • See characterisitc IV curve
  • there's a forward and backward region.
• RGB LED
  • if Common Anode: anode (like + in battery when discharge) should touch positive battery

• Motivation: Provide a stable power (voltage) supply,even tho a lithium-ion battery might drop 4.2v - 2.7v, or there's fluctuations.
  • A regulator is Vout = K * V_ref

• Works same way as linear voltage regulators (see above)

1. A comparator outs high when v+>v_, else low

How comparator works

2. Flip-Flop

• Basic one is active high SR Flip-flop

• Q is output and Q_ is the opposite; S is set, R is reset. So Q follows S

  • S = 1, R = 0, Q= 1; Q_ = 0;
  • S = 0, R = 1, Q = 0, Q_ = 1
    • Note that S = 0 does not set Q = 0, it's R that sets Q to 0
    • That's why it's a "latch", s stays on
  • S = 0 R = 0, Q = 0, Q_ = 1
  • S = 1, R = 1, Q = invalid, Q_=invalid
    • they could be both high, both low, you don't know what happens next
    • So you want to avoid this state
    • So JK Flip-flop came about

    

    flip_flop

• Active low flip-flop, you see S_, R_ for that. When input = 1, you get 0 out

• The gated ones have an enable

1. PCA: printed circuit assembly (PCA) is PCB with electronics soldered on top
2. MOSFET principle:
   • n-type: current flows from drain to source (we're draining the drain). But either terminal can be source/drain. Conditions:
     1. vgate - Vsource > threshold
     2. Vdrain > threshold

        

##Regular Components

1. LCD screen:
   • can show 16x2 chars, so see what can you do with it

1. Basics
   • Image

1. Open Drain

• illustration

1. If servos are not connected, then I2C will lag.
2. Servo motor working principle:
   • Input PWM pulse is 1-2ms long. Feedback loop looks like this: