Description

ABSTRACT

Raspberry Pi beginners can start with Analog Joystick interfacing with the Raspberry Pi, to control an RGB LED which has 3 color emission, Each color can be chosen by making movement on Analog Joystick. This application can be reconfigured to control the appliances or Robots with comfortable handling. Analog joystick is differ based on the hardware design, the Joystick which used here returns analog values, so that every value will be linearly changing, which makes you handle application easily. For example This Joystick refers to be returning the value in one channel for either Left or Right. Similarly returns value on other channel for either Up or Down direction.

HARDWARE REQUIRED

• Raspberry Pi
• SD card
• Power supply
• VGA to HDMI converter (Optional)
• MCP3008 (ADC IC)
• Analog Joystick
• RGB LED

SOFTWARE REQUIRED

• Raspbian Stretch OS      
• SD card Formatter
• Win32DiskImager (or) Etcher

PYTHON LIBRARIES USED

• RPi.GPIO as GPIO (To access the GPIO Pins of Raspberry Pi)

CODE

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)


# read SPI data from MCP3008 chip, 8 possible adc's (0 thru 7)
def readadc(adcnum, clockpin, mosipin, misopin, cspin):
    if ((adcnum > 7) or (adcnum < 0)):
        return -1
    GPIO.output(cspin, True)

    GPIO.output(clockpin, False)  # start clock low
    GPIO.output(cspin, False)  # bring CS low

    commandout = adcnum
    commandout |= 0x18  # start bit + single-ended bit
    commandout <<= 3  # we only need to send 5 bits here
    for i in range(5):
        if (commandout & 0x80):
            GPIO.output(mosipin, True)
        else:
            GPIO.output(mosipin, False)
        commandout <<= 1
        GPIO.output(clockpin, True)
        GPIO.output(clockpin, False)

    adcout = 0
    # read in one empty bit, one null bit and 10 ADC bits
    for i in range(12):
        GPIO.output(clockpin, True)
        GPIO.output(clockpin, False)
        adcout <<= 1
        if (GPIO.input(misopin)):
            adcout |= 0x1

    GPIO.output(cspin, True)

    adcout >>= 1  # first bit is 'null' so drop it
    return adcout


# change these as desired - they're the pins connected from the
# SPI port on the ADC to the Cobbler
SPICLK = 18
SPIMISO = 23
SPIMOSI = 24
SPICS = 25
red_led=16
green_led=20
blue_led=21
# set up the SPI interface pins
GPIO.setup(SPIMOSI, GPIO.OUT)
GPIO.setup(SPIMISO, GPIO.IN)
GPIO.setup(SPICLK, GPIO.OUT)
GPIO.setup(SPICS, GPIO.OUT)
GPIO.setup(red_led, GPIO.OUT)
GPIO.setup(green_led, GPIO.OUT)
GPIO.setup(blue_led, GPIO.OUT)

while True:
    # read the analog pin
    digital_channels = [readadc(pin, SPICLK, SPIMOSI, SPIMISO, SPICS) for pin in range(2)]
    # print (digital_channels)
    if (0 < digital_channels[0] < 100):
        print("Left")
        GPIO.output(red_led, True)
    else:
        GPIO.output(red_led, False)
    if (900 < digital_channels[0] < 1025):
        print("Right")
        GPIO.output(green_led, True)
    else:
        GPIO.output(green_led, False)
    if (0 < digital_channels[1] < 100):
        print("Up")
        GPIO.output(blue_led, True)
    else:
        GPIO.output(blue_led, False)
    if (900 < digital_channels[1] < 1025):
        print("down")