Overview
Things
Story

Introduction
Demonstration
Hardware
Preparation for Ada programming
Where to start: GNAT Programming Studio
Uploading Firmware
Practical Design Considerations
References

Published January 31, 2020 © CC BY-SA

Fluid Ejection Controller

A device for controlled ejection of fluid by volume (medicine/ chemical / fuel) or drop by drop for different applications.

IntermediateFull instructions provided8 hours1,838

Things used in this project

Hardware components

BBC micro:bit board

28YBJ-48 4 Phase Stepper Motor + UNL2003 Driver

SparkFun Breadboard Holder Plastic Base

75 types plastic Gear, Pully, Linear Drive set

Photo-Interruper

3ml Syringe

Resistor 1k ohm

Resistor 2.21k ohm

3 mm LED: Red

3 mm LED: Green

5 mm LED: Yellow

Male Header 40 Position 1 Row (0.1")

Male/Female Jumper Wires

Capacitor 47 µF

Ceramic Disc Capacitor, 0.1 µF

Software apps and online services

AdaCore GNAT Community

Hand tools and fabrication machines

Soldering iron (generic)

Hot glue gun (generic)

Drill / Driver, Cordless

Story

Introduction

This project demonstrates an electronic fluid dropper or injecting device, which can safely transfer controlled volume of liquid periodically.

Possible Areas of Applications

Smart injection timer for medication (Insulin)
Controlled dropper for chemical mixing (acid in water)
Nutrients injector for agriculture (liquid fertilizer)
Scientific tool for fluid mechanics (mass flow rate)
Slow burning fuel injector

Demonstration

pyromaniac application : electronic dropper/ fuel injector

medical application : injection timer

Hardware

Following parts are put together to assemble the hardware :-

Mechanical parts

1 / 2 • Plastic Base, Syringe, Gear Cog , Linear Drive, Cable Clip, Nails and Screws

Electronics & Electro-Mechanical parts

Microbit, Stepper Motor, UNL2003 Motor Driver

Microbit : Runs safe firmware written in ADA for the system
3 RGY LEDs: Status and operation indication
Protoboards: Substrate and interconnection between components
Power Supplies: 2 LiPo Batteries for motor and CR2032 for Microbit
Gear and Linear Drive : Convert rotary motion into linear motion
Stepper Motor: Precise step rotation for controlled motion
B & A button: User control for starting/stopping operation
20 k Pot : Timing delay adjustment input
Plastic Breadboard Holder Base : Support base for the build
Syringe : Hold the fluid to be injected
Photo Interrupt : Optional position sensor

Hardware Pin Map

All the GPIO and ADC, pins are utilized as follows:-

pin budget

Schematic

Here is the schematic for Fluid Ejection Controller hardware prototype :-

Schematic

Build

On a piece of breadboard holder base, a 3ml syringe and a stepper motor is attached with screw, cable clip. Hot glue and epoxy glue is applied as needed:-

1 / 6 • Fully Assembled

Microbit, other electronics components and necessary connectors are soldered together on a protoboard :-

1 / 2 • Controller and Position Sensor

All the wiring are connected according to the schematic to complete the circuit:-

1 / 2 • Full Setup

Preparation for Ada programming

GNAT IDE: download and install GNAT Studio
ARM Driver: download and install ARM Elf Driver
Example Codes : https://github.com/AdaCore/Ada_Drivers_Library

Install all of these in the same directory/folder.

Where to start: GNAT Programming Studio

After downloading/installing GNAT IDE, arm driver into the same directory, open example code from :

C:\GNAT\2019\share\gps\templates\microbit_example

Open one of the examples (i.e. digital_out.gpr) for Microbit according to following steps and edit example project code as needed.

Step 1: Run GPS (GNAT Programming Studio)
Step 2: Select digital_out.gpr example project and double-click to open

Starter code

Step 3: Copy this project's code attached below and replace the example code in main.adb file

Building project on existing example

Following files are the most important files when working with GNAT Studio: -

.gpr file is the GNAT project file for a project

.adb file is the file where Ada code resides (src folder)

.ads files is where the definitions and declarations goes

Uploading Firmware

Once the editing of the code is done, connect Microbit to computer with USB cable ( Windows will make ding-dong sound ).

Then click : Build > Bareboard > Flash to Board > main.adb to flash code to Microbit. The Message window below will show code size and upload percent.

If upload problem occurs, check USB cable or reinstall pyOCD

if compiler throws errors, check the code and fix those.

Flashing code

Practical Design Considerations

This prototype is designed in a way, so that it can be demonstrated easily. But for practical use, consider following issues :

There are different kinds of stepper motor available with various step size and power output. Depending on the fluid viscosity or piston area, more powerful motors might be necessary for some other applications
User interface on this project is very basic, a proper interface will have a display allowing user to choose different options for different types of fluid and timing sequence
Device body should be designed in such a way so the refilling of liquid would be easier for the user
Although stepper motor control is open-loop yet precise position can be determined entirely on the firmware, thus photo-interrupt used in this project is not necessary for position sensing. But it can help to correct the rack and pinion errors in the drive (not implemented yet).

References

Code

------------------------ edge connector pin mapping ------------------------------
----------------------------------------------------------------------------------
-- See here : https://makecode.microbit.org/device/pins --------------------------

--  pin(code)      pin (edge connector pads)      hardware connected
--   2         --  large via p2                   -- UNL2003 Ch1
--   13        --  small pad p13                  -- UNL2003 Ch2
--   15        --  small pad p15                  -- UNL2003 CH3
--   14        --  small pad p14                  -- UNL2003 CH4
--   0         --  large via p0                   -- photo interrupt
--   1         --  large via p1                   -- 20 K pot
--   7         --  small pad p7                   -- RED LED
--   10        --  small pad p10                  -- GREEN LED 
--   8         --  small pad p8                   -- YELLOW LED
----------------------------------------------------------------------------------
------------------------- end of comment section ---------------------------------

-- packages/drivers

with MicroBit.IOs;     use MicroBit.IOs;     -- includes microbit GPIO
with MicroBit.Time;                          -- includes microbit time
with MicroBit.Buttons; use MicroBit.Buttons; -- includes ubit button


-- following part for variable declearation
procedure Main is


   Phase_1 : constant MicroBit.IOs.Pin_Id := 2;
   Phase_2 : constant MicroBit.IOs.Pin_Id := 13;
   Phase_3 : constant MicroBit.IOs.Pin_Id := 15;
   Phase_4 : constant MicroBit.IOs.Pin_Id := 14;
   RED_LED :constant MicroBit.IOs.Pin_Id := 7;
   YELLOW_LED :constant MicroBit.IOs.Pin_Id := 8;
   GREEN_LED : constant MicroBit.IOs.Pin_Id := 10;

   POT_ADC_Val : MicroBit.IOs.Analog_Value;  -- 20k pot on pin 1
   POS_ADC_Val : MicroBit.IOs.Analog_Value;  -- photo interrupt on pin 0
   ADC_Temp : MicroBit.IOs.Analog_Value ;    -- ADC type temp variable
   Position_Counter : Integer :=0;



   -- following part for initialization (one time run code)
begin
-- de-energize all the coils of stepper motor
   MicroBit.IOs.Set (Phase_1, False);
   MicroBit.IOs.Set (Phase_2, False);
   MicroBit.IOs.Set (Phase_3, False);
   MicroBit.IOs.Set (Phase_4, False);
   MicroBit.Time.Delay_Ms (100);

   ADC_Temp := 950;
   POT_ADC_Val := MicroBit.IOs.Analog(1);
   POS_ADC_Val := MicroBit.IOs.Analog(0);
  -- loop until button A is pressed
   while MicroBit.Buttons.State (Button_A) /= Pressed loop

      for I in 0 .. (POT_ADC_Val/20) loop
         MicroBit.IOs.Set (RED_LED, True);
         MicroBit.Time.Delay_Ms (250);
         MicroBit.IOs.Set (RED_LED, False);
         MicroBit.Time.Delay_Ms (250);
       

      end loop;

      MicroBit.IOs.Set (GREEN_LED, True);
      MicroBit.Time.Delay_Ms (100);
      MicroBit.IOs.Set (GREEN_LED, False);
      MicroBit.Time.Delay_Ms (150);

      POT_ADC_Val := MicroBit.IOs.Analog(1);
      POS_ADC_Val := MicroBit.IOs.Analog(0);

   end loop;



   --  next part infinite loop (main loop run code)
   loop
      while Position_Counter <7  loop
         POT_ADC_Val := MicroBit.IOs.Analog(1); -- read pot for timing delay
         --MicroBit.Time.Delay_Ms (2000);
         -- blink indication to user
         for I in 0 .. (POT_ADC_Val/20) loop
            MicroBit.IOs.Set (GREEN_LED, True);
            MicroBit.Time.Delay_Ms (500);
            MicroBit.IOs.Set (GREEN_LED, False);
            MicroBit.Time.Delay_Ms (500);
         end loop;
         -- push shaft by energizing 4 coil phases one at a time
         for Y in 0 ..11 loop -- 12 loops make 0.1 ml volume displacement
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, True);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, True);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, True);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, True);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
         end loop;
         -- count holes in shaft with photo interrupt
         if POS_ADC_Val< ADC_Temp then
            MicroBit.IOs.Set (YELLOW_LED,True);
            Position_Counter := Position_Counter+1;
         else
            MicroBit.IOs.Set (YELLOW_LED,False);
         end if;
      end loop;
      while Position_Counter >0  loop

         -- MicroBit.Time.Delay_Ms (2000);
         for I in 0 .. (POT_ADC_Val/20) loop
            MicroBit.IOs.Set (RED_LED, True);
            MicroBit.Time.Delay_Ms (500);
            MicroBit.IOs.Set (RED_LED, False);
            MicroBit.Time.Delay_Ms (500);
         end loop;
         -- pull shaft by energizing 4 coil phases  in reverse order
         for X in 0 ..11 loop  -- 0.1 ml volume transfer
            MicroBit.IOs.Set (Phase_1, True);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, True);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, True);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, True);
            MicroBit.Time.Delay_Ms (9);
           

         end loop;
         -- count holes in shaft with photo interrupt
         if POS_ADC_Val< ADC_Temp then
            MicroBit.IOs.Set (YELLOW_LED,True);
            Position_Counter := Position_Counter-1;
         else
            MicroBit.IOs.Set (YELLOW_LED,False);
         end if;
      end loop;
         
         while True loop
         null; -- stop operation
         end loop;

   end loop;
end Main;

-- I have written this code based on examples/drivers from the following link:
-- https://github.com/AdaCore/Ada_Drivers_Library/tree/master/boards/MicroBit
-- by Fabien-Chouteau's work on behalf of ADA driver library on github        

-- DISCLAIMER: License agreement as per contest rules  --

------------------------ edge connector pin mapping ------------------------------
----------------------------------------------------------------------------------
-- See here : https://makecode.microbit.org/device/pins --------------------------

--  pin(code)      pin (edge connector pads)      hardware connected
--   2         --  large via p2                   -- UNL2003 Ch1
--   13        --  small pad p13                  -- UNL2003 Ch2
--   15        --  small pad p15                  -- UNL2003 CH3
--   14        --  small pad p14                  -- UNL2003 CH4
--   0         --  large via p0                   -- photo interrupt
--   1         --  large via p1                   -- 20 K pot
--   7         --  small pad p7                   -- RED LED
--   10        --  small pad p10                  -- GREEN LED 
--   8         --  small pad p8                   -- YELLOW LED
----------------------------------------------------------------------------------
------------------------- end of comment section ---------------------------------

-- packages/drivers

with MicroBit.IOs;     use MicroBit.IOs;     -- includes microbit GPIO
with MicroBit.Time;                          -- includes microbit time
with MicroBit.Buttons; use MicroBit.Buttons; -- includes ubit button



procedure Main is

  -- assigning gpio and adc pins
   Phase_1 : constant MicroBit.IOs.Pin_Id := 2;
   Phase_2 : constant MicroBit.IOs.Pin_Id := 13;
   Phase_3 : constant MicroBit.IOs.Pin_Id := 15;
   Phase_4 : constant MicroBit.IOs.Pin_Id := 14;
   RED_LED :constant MicroBit.IOs.Pin_Id := 7;
   YELLOW_LED :constant MicroBit.IOs.Pin_Id := 8;
   GREEN_LED : constant MicroBit.IOs.Pin_Id := 10;

   -- following part for variable declearation
   POT_ADC_Val : MicroBit.IOs.Analog_Value;  -- 20k pot on pin 1
   POS_ADC_Val : MicroBit.IOs.Analog_Value;  -- photo interrupt on pin 0
   ADC_Temp : MicroBit.IOs.Analog_Value ;    -- ADC type temp variable
   Position_Counter : Integer :=0;



   -- following part for initialization (one time run code)
begin
   -- de-energize all the coils of stepper motor 
   MicroBit.IOs.Set (Phase_1, False);
   MicroBit.IOs.Set (Phase_2, False);
   MicroBit.IOs.Set (Phase_3, False);
   MicroBit.IOs.Set (Phase_4, False);
   MicroBit.Time.Delay_Ms (100);

   ADC_Temp := 950;
   POT_ADC_Val := MicroBit.IOs.Analog(1);
   POS_ADC_Val := MicroBit.IOs.Analog(0);
   -- loop until button A is pressed
   while MicroBit.Buttons.State (Button_A) /= Pressed loop
      -- blink led depending on pot value
      for I in 0 .. (POT_ADC_Val/20) loop
         MicroBit.IOs.Set (RED_LED, True);
         MicroBit.Time.Delay_Ms (250);
         MicroBit.IOs.Set (RED_LED, False);
         MicroBit.Time.Delay_Ms (250);


      end loop;

      MicroBit.IOs.Set (GREEN_LED, True);
      MicroBit.Time.Delay_Ms (100);
      MicroBit.IOs.Set (GREEN_LED, False);
      MicroBit.Time.Delay_Ms (150);

      POT_ADC_Val := MicroBit.IOs.Analog(1);
      POS_ADC_Val := MicroBit.IOs.Analog(0);

   end loop;



   
   loop
      -- loop until B is not pressed
      while MicroBit.Buttons.State (Button_B) /= Pressed   loop
         -- read pot for taking user input to adjust displacement length
         POT_ADC_Val := MicroBit.IOs.Analog(1); 
         --MicroBit.Time.Delay_Ms (2000);

          -- led blink for indication (debugging)
            MicroBit.IOs.Set (RED_LED, True);
            MicroBit.Time.Delay_Ms (500);
            MicroBit.IOs.Set (RED_LED, False);
            MicroBit.Time.Delay_Ms (500);
        
         -- push shaft by powering 4 phases/coils one at a time
         -- 12 loops make 0.1 ml volume displacement
         for Y in 0 ..(POT_ADC_Val/50) loop 
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, True);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, True);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, True);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, True);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
         end loop;
         -- count holes in shaft with photo interrupt
         if POS_ADC_Val< ADC_Temp then
         -- indication led blink for user
            MicroBit.IOs.Set (YELLOW_LED,True);
            Position_Counter := Position_Counter+1;
         else
            MicroBit.IOs.Set (YELLOW_LED,False);
         end if;
      end loop;
      -- loop while B button is pressed and hold
      while  MicroBit.Buttons.State (Button_B) = Pressed   loop

         -- MicroBit.Time.Delay_Ms (2000);
         -- read pot for taking user input to adjust displacement length
         POT_ADC_Val := MicroBit.IOs.Analog(1); 
        
            MicroBit.IOs.Set (RED_LED, True);
            MicroBit.Time.Delay_Ms (250);
            MicroBit.IOs.Set (RED_LED, False);
            MicroBit.Time.Delay_Ms (250);
        
         --  pull shaft by powering 4 phases/coils in reverse order
         for X in 0 ..(POT_ADC_Val/50) loop  
            MicroBit.IOs.Set (Phase_1, True);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, True);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, True);
            MicroBit.IOs.Set (Phase_4, False);
            MicroBit.Time.Delay_Ms (9);
            MicroBit.IOs.Set (Phase_1, False);
            MicroBit.IOs.Set (Phase_2, False);
            MicroBit.IOs.Set (Phase_3, False);
            MicroBit.IOs.Set (Phase_4, True);
            MicroBit.Time.Delay_Ms (9);


         end loop;
         -- count holes in shaft with photo interrupt
         if POS_ADC_Val< ADC_Temp then
            MicroBit.IOs.Set (YELLOW_LED,True);
            Position_Counter := Position_Counter+1;
         else
            MicroBit.IOs.Set (YELLOW_LED,False);
         end if;
      end loop;
      -- when B button is released, halt device operation 
      while True loop
         null; -- stop operation, reset device to restart
         end loop;

   end loop;
end Main;

-- I have written this code based on examples/drivers from the following link:
-- https://github.com/AdaCore/Ada_Drivers_Library/tree/master/boards/MicroBit
-- by Fabien-Chouteau's work on behalf of ADA driver library on github        

-- DISCLAIMER: License agreement as per contest rules  --

Credits

Shahariar

74 projects • 265 followers

"What Kills a 'Great life' is a 'Good Life', which is Living a Life Inside While Loop"

Thanks to Fabien Chouteau.

Fluid Ejection Controller