12. Output devices¶

This week we did not have access the lab, so I will update it later when it is done.

Download files:¶

RML files and PNG files:
Output board Traces and Outline

Eagle Files:
Click to download

Arduino File:

H-Bridge code

Servo code

Assignment Objectives:¶

Individual assignment:
Add an output device to a microcontroller board you’ve designed, and program it to do something.

Group assignment:
Measure the power consumption of an output device.

Group assignment:¶

In this part we measured the power consumption of a DC motor using a DC motor output board.

Datasheet01

The Power P (in Watt) is calculated by:

P (watts) = V (volts) x I (amps)

Where V is the voltage across the load and I is the current passing through the load. To measure voltage, the digital multimeter is connected in parallel with the load, and to measure the current passing through, the digital multimeter is connected in series with the load. Remember to move digital multimeter positive test lead to current measuring position before connecting in series with the load.

Measuring the voltage.

gruop_01

Measuring the current.

gruop_02

Individual assignment:¶

I continued the theme from input week, to design a puzzle shaped PCB, that can be connected to my Hello.World PCB.

In this week, I will design a board to control a DC motor using H-bridge.

Data sheet of H-BRIDGE A4953:¶

From the data sheet:

The H-bridge is designed for pulse width modulated (PWM) control of DC motors, the A4952 and A4953 are capable of peak output currents to ±2 A and operating voltages to 40 V.
The maximum values of the inputs and the outputs.
The pin layout of the IC.
The PWM to control the motor, changing the direction, and brake the motor, to help us program the microcontroller.
Layout:
The PCB should have a thick ground plane. For optimum electrical and thermal performance, the A4952/A4953 must be soldered directly onto the board. On the underside of the A4952/A4953 package is an exposed pad, which provides a path for enhanced thermal dissipation. The thermal pad must be soldered directly to an exposed surface on the PCB in order to achieve optimal thermal conduction. Thermal vias are used to transfer heat to other layers of the PCB.
The load supply pin, VBB, should be decoupled with an electrolytic capacitor (typically 100 μF) in parallel with a lower valued ceramic capacitor placed as close as practicable to the device.

Design the PCB in eagle:¶

Determine the parts that we need:¶

I added a voltage regulator to power the device with no need to connect and 5V source.

Part name	Footprint	Quantity
PMIC_H-BRIDGE_A4953_PAD	SOIC8	1
VR_REGULATOR-SOT23	SOT23	1
CONN_02X2-PINHEAD-SMD	2X02SMD	3
CAP_UNPOLARIZED 1μF	C1206FAB	1
CAP_UNPOLARIZED 10μF	C1206FAB	1
Resistor 1k	R1206FAB	1
LED	LED1206FAB	1

Prepare the Schematic:¶

I have added the parts from the table, where I have three jumpers, one to input voltage source Vbb, one to give the output to the motor, and the last one to get the signals from the microcontroller, as well as, power it with +5V and ground.

Eagle Schematic

Also, I have added a LED to indicate that the board is working when it is connected to a power source.

Board:¶

I have loaded the fab DRC file, under Sizes tab I changed the *minimum width* value from *10mil* to *16mil*, so when I do the *Autorouter* I get the right value.

DCR Sizes

Also that I have keep in mind that the lines from *Vbb* and its *ground* need to be **24mil** width.

PCB

Also I have put indications for *Vbb*, the gournd, the output for the motor, and *Vcc* to not be mixed up with the jumpers, and it is easier to understand.

I have made a profile to prepare the PCB file to be exported, just showing the pads, wire lines, and the dimension of the PCB, you can edit it in the yellow highlighted button.

I exported it as monochrome, with 1000 DPI.

Export PNG

Using photoshop, I have made the traces and cut images:

Traces:
Export PNG

Outline:
Export PNG

Generate RML files from mods:¶

Like the process of the input week, we make sure that the resolution is 1000 DPI for both files, and the origin is changed x, y, z to zero

For traces, the bit selected is *1/64"*, and the offset number is *4*.

From mods page we open program Ronald SRM-20mill.

Machines --> Ronald --> SRM-20 mill--> PCB

mods traces

Then I checked the path file to make sure there are no connected wires and/or pads, it should be at least on line between the wire and/or pads.

mods traces output

For the outline, the bit selected is *1/32"*, and the offset number is the default *1*.

mods outline

Problem that I have:¶

After getting back to the lab, I have milled and soldered the output board and try to started it but I did not work, the same problem happened with my colleague Hani with his board, after a week, he figured it out the problem was we both did not connected the LSS to the ground, while it is mentioned in the data sheet it was optional!!!

Problem

Redo the board:¶

I have just connected the LSS to the ground, and resize the board to be used on my final project.

Updated schematics:

redo_hbridge_schematics

Updated board design:

redo_hbridge

Code:¶

It is a simple on/off with timer, controlled by the ATtiny44

const int motorPin1 = 0;
const int motorPin2 = 1;

const int LEDred = 3;

void setup() {
  // put your setup code here, to run once:
  pinMode(motorPin1, OUTPUT);
  pinMode(motorPin2, OUTPUT);
  pinMode(LEDred, OUTPUT);
}

void loop() {
  digitalWrite(motorPin1, HIGH);
  digitalWrite(motorPin2, LOW);
  digitalWrite(LEDred, HIGH);
  delay(5000);

  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, LOW);
  digitalWrite(LEDred, LOW);
  delay(3000);

  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, HIGH);
  digitalWrite(LEDred, HIGH);
  delay(5000);

  digitalWrite(motorPin1, LOW);
  digitalWrite(motorPin2, LOW);
  digitalWrite(LEDred, LOW);
  delay(3000);
}

Fabricate the board:¶

Milling the board:¶

Videos of milling the old board:

Old board before and after soldering, notice the LSS pin is not connected to the ground.

OLD_hbridge

Hero shoot!!!¶

New board H-bridge:

new_hbridge

Video of the board and the code working:

Working with Arduino kit:¶

I did a small project, where I connected two servo motors to an Arduino, where the output signal to servo one is not the same of the servo 2.
And I program is to move to three locations 0°, 90° , and 180°.

Servo 1	Servo 2
0°	90°
90°	180°
180°	0°

Connection:¶

The servo has three pins; Voltage in, ground, and signal, where the voltage is connected to 5V+ from the Arduino, ground to ground, and signal to pin 3 and pin 5 for each servo.

TinkerCad connection 01

TinkerCad connection 02

Code:¶

// Including the Servo library
#include <Servo.h>
// Declare the Servo pins
int servoPin1 = 3;
int servoPin2 = 5;
// Create a servo objects
Servo Servo1; Servo Servo2;
void setup() {
   // We need to attach the servo to the used pins number
   Servo1.attach(servoPin1);
   Servo2.attach(servoPin2);
}
void loop(){

   Servo1.write(0);     // Make servo1 go to 0 degrees
   Servo2.write(90);    // Make servo2 go to 90 degrees
   delay(1000);

   Servo1.write(90);    // Make servo1 go to 90 degrees
   Servo2.write(180);   // Make servo2 go to 180 degrees
   delay(1000);

   Servo1.write(180);   // Make servo1 go to 180 degrees
   Servo2.write(0);     // Make servo2 go to 0 degrees
   delay(1000);
}

Parts used:¶

Arduino UNO ATMEGA328P.
Mini servo motor SG90 9G servo.
Servo motor MG995 metal gear 180 degrees.

12. Output devices¶

Download files:¶

Assignment Objectives:¶

Group assignment:¶

Individual assignment:¶

Data sheet of H-BRIDGE A4953:¶

Design the PCB in eagle:¶

Determine the parts that we need:¶

Prepare the Schematic:¶

Board:¶

Generate RML files from mods:¶

Problem that I have:¶

Redo the board:¶

Code:¶

Fabricate the board:¶

Milling the board:¶

Hero shoot!!!¶

Working with Arduino kit:¶

Connection:¶

Code:¶

Parts used:¶

Hero shoots:¶