Review

• Ran GPIO Blinking LED code on Pi with jumper cables attached correctly.
• Changed the blinking rate of the LED
• Added another LED to the program and the wiring such that the LEDs alternate being ON?
  • (if not then do this today)

to light up an LED

3.3V into long end

other end to ground (GND)

GND Pin

GPIO Pin

Breadboard

• aka proto board

Components

• jumper cable
• LED
• resistor
• pushbutton
• conductive wire

You will use this exact setup for your next assignment

Today:

• GPIO Pushbuttons
  • see mine work
  • circuit diagrams of both versions
  • see code that prints pin level
    • wire breadboard for this program
    • compile and run code
  • add program control of a second LED and have the input pin voltage (the button push) decide which LED is blinking
  • extra time (start assignment?)

GPIO C Programming

• lets just use gpio.h in C
  • why do it in ARM Assembly?
• we read and write to specific memory addresses to control the Pi's GPIO pin voltages
  • GPFSEL[0-5]
    • $$3 \times 53 = 159 < 192 = 32 \times 6$$
  • GPSET[0,1] 
  • GPCLR[0,1]
  • GPLEV[0,1]
    • $$ 53 < 64 = 32\times 2$$