BakeBit - LED Bar

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1 Introduction

LED Bar

• The BakeBit - LED-Bar is a multiple-LED module. It has five LEDs and each LED is controlled by a WS2812 chip.
• These five LEDs are in series connection.

2 Hardware Spec

• Standard 2.0mm pitch 4-Pin BakeBit Interface
• Multi-color R, G, B LED
• True Color

• Pin Description:

Pin	Description
GND	Ground
5V	5V Supply Voltage
NC	Not Connected
SIG	Signal

3 Code Sample(1): LED Bar

By running this code sample users can adjust the LED bar with the rotary angle sensor module.
A BakeBit - Rotary Angle Sensor module is needed in this test case.

3.1 Hardware Setup

Connect the LED Bar module to the NEO-Hub's D3 and the rotary angle sensor module to the NEO-Hub's A0:

3.2 Source Code

import time
import bakebit
import random
 
# Connect the BakeBit LED Bar to digital port D3
# DI,DCKI,VCC,GND
ledbar = 3
 
# Connect the BakeBit Rotary Angle Sensor to analog port A0
# SIG,NC,VCC,GND
potentiometer = 0
 
# Reference voltage of ADC is 5v
adc_ref = 5
 
# Vcc of the bakebit interface is normally 5v
bakebit_vcc = 5
 
# Full value of the rotary angle is 360 degrees, as per it's specs (0 to 360)
full_angle = 360
 
bakebit.pinMode(potentiometer,"INPUT")
bakebit.pinMode(ledbar,"OUTPUT")
time.sleep(1)
 
# LED Bar methods
# bakebit.bakeBitLedBar_Init(pin, chipset, numOfLED)
# bakebit.bakeBitLedBar_Release(pin)
# bakebit.bakeBitLedBar_Show(pin,colorHigh,colorLow)
 
bakebit.bakeBitLedBar_Init(ledbar, 0, 5)
time.sleep(.5)
 
old_color = 0
while True:
    try:
        # Read sensor value from potentiometer
        sensor_value = bakebit.analogRead(potentiometer)
 
        # Calculate voltage
        voltage = round((float)(sensor_value) * adc_ref / 1023, 2)
 
        # Calculate rotation in degrees (0 to 360)
        degrees = round((voltage * full_angle) / bakebit_vcc, 2)
        print("sensor_value = %d voltage = %.2f degrees = %.1f" % (sensor_value, voltage, degrees))
 
        color16bit = 0
        if degrees > 0:
            color16bit = color16bit | bakebit.Green
        if degrees > 72:
            color16bit = color16bit | (bakebit.Green<<3)
        if degrees > 144:
            color16bit = color16bit | (bakebit.Green << 6)
        if degrees > 216:
            color16bit = color16bit | (bakebit.Yellow << 9)
        if degrees > 288:
            color16bit = color16bit | (bakebit.Red << 12)
        if degrees == 360:
            color16bit = 0
            color16bit = color16bit | bakebit.Red
            color16bit = color16bit | (bakebit.Red << 3)
            color16bit = color16bit | (bakebit.Red << 6)
            color16bit = color16bit | (bakebit.Red << 9)
            color16bit = color16bit | (bakebit.Red << 12)
 
        if color16bit == old_color:
            continue
        old_color = color16bit
 
        lowBits = color16bit & 255
        highBits = (color16bit & (255<<8))>>8
        print("%s %s" % ('{0:08b}'.format(highBits), '{0:08b}'.format(lowBits)))
        bakebit.bakeBitLedBar_Show(ledbar, highBits, lowBits)
        time.sleep(.2)
 
    except KeyboardInterrupt:
        bakebit.bakeBitLedBar_Release(ledbar)
        time.sleep(.2)
        break
    except IOError:
        print ("Error")

Github

3.3 Run Code Sample

Before you run the code sample you need to follow the steps in bakebit tutorial to install the BakeBit package.
Enter the "BakeBit/Software/Python" directory and run the "bakebit_prj_LEDBar_And_RotaryAngleSensor.py" program:

cd ~/BakeBit/Software/Python
sudo python bakebit_prj_LEDBar_And_RotaryAngleSensor.py

3.4 Observation

When you rotate the rotary angle sensor module the LEDs on the LED Bar will be turned on or off.

4 Code Sample(2): Smart Lighting

By running this code sample your system adjusts the LEDs on the LED module according to surrounding lightness. When the surrounding environment becomes darker the LEDs will be brighter. When the surrounding becomes bright enough the LEDs will be completely off.
A BakeBit - Light Sensor module is needed in this test case. For more details about the light sensor module refer to the BakeBit - Light Sensor page.

5 Resources

• [Schematic](BakeBit - LED Bar.pdf)
• [BakeBit Github Project Page](https://github.com/friendlyarm/BakeBit)
• [BakeBit Starter Kit User's manual](http://wiki.friendlyarm.com/bakebit/bakebit_starter_kit_manual_en.pdf)

6 Update Log

6.1 December-13-2016

• Released English Version