Freemometer V2.1 - Hacking the IKEA DEKAD into a notification device with a Pico and MicroPython

This is V2 of a project I did a few years ago.  The IKEA DEKAD is a pretty package that makes a nice project case and comes with awesome mechanical bells. The Freemometer replaces the clock mechanism with a Servo and adds a couple status LEDs.  A microcontroller is added to run the servo, LEDs, and the motor that drives the alarm bells.  It is really the alarm bells that make the project.  

The Pico is a lot more powerful than the Arduino-based first version of this device.  It is powerful enough to write code in Python which I find less stressful for a project like this that is not real-time in nature.

This project uses a Pico W which means it can reach out to some site or socket to get data and then run lights on the servo or the bell.  It also means you can stand up a web server or some other inbound listener that external parties can call.  I tend to Bluetooth into the virtual serial port on the HC-05 so I don't have to enable WebREPL or some other inbound wifi programming port.

Final Product

The Freemometer with a Servo Dial, two NeoPixel LEDs, the alarm bells, and a Pico controller

Schematic and Design

Power is pulled in either off the jack mounted to the back of the case or over the Pico USB connection.  
  • I replaced the original LEDs with Adafruit through hole Neopixels.  
  • I shorted the jumper on the DRV8833 board so that it pulls motor power from VCC and not somewhere else. The motor ran off batteries in the original unit so I'm not worried about the draw.
  • The HC-06 is on the default UART 0 pins GPIO0/GPIO1

The Pico is so flexible that the pins don't really matter.  It would have been better if I could have used pins on only one edge of the Pico. That would have made board positioning easier.

Components

In Action

Disassembly

The back side of the IKEA Decad.  We're going to remove the three screws and the clock internals but leave the switch in place to disable the ringer.
The Dekad inners. There is a lot of empty space.  We're going to keep the motor and bell ringer in the top



The upper bolts holding the bells and the feed have been removed. They are threaded to nuts inset into the mounting plate that holds the guts


The motor and clock mechanism is mounted to the front plate.  It all can be lifted out once you remove the feet and bell mounts.

This is the front side of the face plate after removal from the circular frame.  The frame has a lip on the front that holds the stack: Spacer ring, glass face Clock face and mounted components
The Front plate with the clock mechanism was removed. You can see the clock mechanism with the time adjustment knobs.

The clock mechanism is a compact modular unit.  I may just leave all that in the unit in the future and just do a motor/blinkenlights build.

Clock mechanism internals.  It is so clean it seems like it should be retained or reused for something.  I'm not sure what yet.

But I didn't do that. I took it all apart to reuse the back panel to mount the servo.

The back panel of the clock mount has been put back on the clock faceplate.

How are we going to solidly mount the servo where it will clear the battery section of the back panel.  This was the only orientation that worked.
It almost worked.



I'm going to make it work so I just hot glue the sh*t out of it.

We'll just hack a bit of a channel in the AA battery compartment and the servo will fit.  I hacked more than I needed because you can see that there is more hole than is needed. It worked out fine though because I used the extra space for wires.

Yup the Pico W fits perfectly in the AA battery compartment

Face

I pulled the paper face off the front mounting plate to double-sided tape my own. The servo only has 160 degrees of range so the full clock face would have been misleading

Motor Driver

I didn't want to solder any resistors or transistors so I bought these super cheap DRV8833.  I'm only using 1/2, really 1/4 of the board but they were $2 each from a no-name Amazon vendor.  The Pico will use two pins to drive the motor,  IN1 and IN2.  We could have grounded one of the pins and controlled it all from one line.  I did it this way in case I needed to programmatically reverse the direction of the motor.  This was way overkill but the Pico has pins to burn and this DRV8833 had the pins.

Wires Everywhere

There are a whole bunch of wires.  I mounted the jack in the back where one of the time change knobs was and then ran all the 5V and GND to the jack.  Only one component needed 3.3v power and I picked that off of the Pi 3.3 pin.


The LED wires in this picture, yellow shrinkwrap, are from a previous version that used two-wire reversible Red/Green LEDs. The schematic above uses two 4-pin Neopixel through holes.  The front looks the same.  The new NeoPixels need power, ground, and then a daisy chain off the controller.

Assembly

I replaced the standard clock face with a circular gauge and some art below it. The edges of the face are hidden by the rim of the DEKAD case. The old minute hand has been mounted to the servo as the gauge needle. The servo arm screw goes through it and a very light hot glue secured the needle and the end of the servo arm.

You can see the Pico and the power jack. The LED holes could have been neater or better aligned or I could just make a new face that lined up with the LED position and tape it to the plastic face.  The clock minute hand is reused here. 

The back of the Dekad assembled. The battery cover will hide the details. You can see the power jack in the old time-adjustment hole created when removed the clock. 

The Pico is inside the battery compartment.  This lets me use wired connectivity for development without any disassembly other than removing the battery cover.

This particular device also has an HC-06 Bluetooth clone with the REPL console duplicated to it.

Sample Code

This code uses a servo class from the freemansoft GitHub repo.  Everything else is a standard library.


from machine import Pin, PWM
import time
import machine, neopixel

# neopixels
neopixel_pin_num = 16
num_neopixels = 2
motor_pin_1_num = 18
motor_pin_2_num = 19
# The face servo moter control pin
servo_pin_num = 22


np = neopixel.NeoPixel(machine.Pin(neopixel_pin_num), num_neopixels)
# We could have grounded one of the DRV8833 inputs but instead hook this up as if it is a reversable motor
motor1a = Pin(motor_pin_1_num, Pin.OUT)
motor1b = Pin(motor_pin_2_num, Pin.OUT)

led = machine.Pin.board.LED
led.value(1)

print("show some pretty colors")
# fade in/out
for i in range(0, 4 * 256, 4):
    # set all pixels
    for j in range(num_neopixels):
        if (i // 256) % 2 == 0:
            val = i & 0xFF
        else:
            val = 255 - (i & 0xFF)
        np[j] = (val, 0, 255 - val)
    np.write()
    time.sleep_ms(10)

# clear
for i in range(num_neopixels):
    np[i] = (0, 0, 0)

np.write()

# go motor go - they need to be opposite values
print("Motor like a bat out of hell")
motor1a.value(0)
motor1b.value(1)
time.sleep(1)

# stop motor stop
print("Motor off")
motor1a.value(0)
motor1b.value(0)
time.sleep(1)

# lets try motor speed control with PWM
pwm1a = PWM(motor1b)
pwm1a.freq(10000)
print("Motor 10000/65000")
np[0] = (64, 0, 0)  # set to red, full brightness
np.write()
pwm1a.duty_u16(10000)  # out of 65000
time.sleep(1)
print("Motor 25000/65000")
np[0] = (64, 64, 0)  # set to red, full brightness
np.write()
pwm1a.duty_u16(25000)  # out of 65000
time.sleep(1)
print("Motor 45000/65000")
np[0] = (0, 64, 0)  # set to red, full brightness
np.write()
pwm1a.duty_u16(45000)  # out of 65000
time.sleep(1)
print("Motor 00000/65000")
np[0] = (0, 64, 64)  # set to red, full brightness
np.write()
pwm1a.duty_u16(00000)  # out of 65000
time.sleep(1)
pwm1a.deinit()
np[0] = (0, 0, 64)  # set to red, full brightness
np.write()
time.sleep(1)
np[0] = (0, 0, 0)  # set to red, full brightness
np.write()

# off
print("both leds off")
np[0] = (0, 0, 0)
np[1] = (0, 0, 0)
np.write()
time.sleep(1)

from servo import Servo

servo = Servo(Pin(servo_pin_num, Pin.OUT))
print("servo 0")
servo.write_angle(0)
time.sleep(1)
print("Servo 80")
servo.write_angle(80)
time.sleep(1)
print("servo 160")
servo.write_angle(160)
time.sleep(1)
servo.write_us(0)

Video

  • V2 R/G LEDs https://youtu.be/Le0Ztm0HpiY
  • V2.1 Neopixel https://youtu.be/i3CMY9Kcrhw

Revision History

Created 2023 01
Revised to use NeoPixels through hole instead of R/G two wire

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