Week 13, Output Devices

This week assignment tasks are

is to measure something: add a sensor to a microcontroller board which was designed and built to read something.

add an output device to a microcontroller board and programmed it to do something

Output devices

The output devices in electronic systems transfer energy from the electrical energy that has been processed to another kind of energy, often light, sound or movement (kinetic). Output devices can be digital or analogue.
Examples are:
LED, Lamp, Buzzer, Piezo, Motors, Solenoid, Relay, 7-segment display, etc

The signal output can be from a pin of a Attiny45 chip to activate any of the output device mentioned.

Design and Conceptualization

I intented to use a DC Buzzer Single Tone 2.8kHz Piezo 3 ~ 16V 102dB @ 12V, 30mm, as my output device.

Buzzer and click link here for its datasheet.

Although the supply is a 5VDC of an USB, the buzzer operating voltage is between 3V to 16V according the datasheet. That's the reason I'm using this buzzer device. I also added a LED to create visual indication that the output signal from the Attiny45 pin.

The design I'll be using is the same mentioned in Week 11.
The board I am using will have an input devices connected to the PCB and the same goes to the output pins terminal.


Simple input and output circuit sketch

Making the PCB

EagleCAD was used to design the circuit. The operating procedure will not be repeated here as it was described in Week 6.
Below are the screen shots of the final input and output board.

Schematic of the input and output circuit


Layout of the input and output circuit components

The working files of schematic and board EagleCAD design can be downloaded here with a Right Click over them and "Save Link As".

Testing out

I did a continuity test on the PCB and found there are some paths were shorted together. Did another PCB routing by tweaking the depth of cut parameters slightly, meaning a slightly deeper cut. The results were worse than before, many paths were completely routed out causing open circuit between connectors. Routed another PCB with previous settings and did some rectifications and was able to clear the faults. After soldering components onto the pcb, noticed the paths near he pins of the attiny45 chip. Tried removing but the paths seems to have shorted together after verification with a multi meter. Had no choice but to remove the Attiny45. The pic below showed the condition of scorched terminal pins and amount of solder fused onto the copper surface.


Faulty input and output pcb

Did another round of PCB routing but I removed the capacitor and resistor to reduce fault variables, performed continuity test, soldered on the components and found a short between a pin terminal and to the adjacent copper paths. These pictures below made me understanded the meaning of the straws tat broke the camel back.



Pins broke and destoyed the copper surfaces

I am doing it my way

I was resolved to doing my own way to make it work. I first sketch out the circuit and shown below.



Followed up with the standard procedure of bootloader the Attiny45 chip and uploading the program into it. The final circuit would looked like as shown below.



The video below showed the function of circuit.



The working files of Input and Output can be downloaded here with a Right Click over them and "Save Link As".

Making the Ouput PCB Board (Update)

Remaking the PCB board for the output devices with a new design. The LDR will still be used as an input sensor and will output a continous messages with different sentence depending on the state of the input sensor. A buzzer and a LED will be added to enhanced the display.
The program was written in Arduino IDE and then the circuit was designed with EagleCAD before being milled out onto a PCB.


Output Schematic Drawing (Right click and save link as)


Input Board Drawing (Right click and save link as)

The programming file can be downloaded here.

The circuit was then milled out onto a PCB.

Output Device PCB

I ran into some problems when I tried to upload the program but I still can't resolved it. I got my colleague Mark to help me troubleshoot and he discovered there was a missing connect between PB2 of the Attiny45 to one of header pins. The missing connections were RX nd TX of the Attiny45 to the TX and RX connection of the serial board. Which in this case the Attiny45 TX to serial board RX was missing; indicated by a blue ring in the picture below.
It was a crucial connection when loading the program via FabISP but not when using Arduino as an ISP. I just added the connection with a wire for use later with a FabISP.


Toubleshooting the Output PCB

The PCB was then populated with components after the troubleshooting and loading of the program file.



The video showed the output messages, buzzer and LED in relation to the status of the LDR sensor when it was covered and uncovered.



My comments

I think working with both Input and Output Devices would gain better understanding for the students.