For Output devices, I am interfacing an LCD Display and a WiFi Module ESP8266, which will be used as part of my final project to display various parameters of interest.

I started by making my custom PCB by keeping in mind the requirements of my final project. I have chosen a modular design by which the Output and few other functions of my final project will be handled by the PIC16F877A microcontroller. I decided to make a generic development board so that I can build the other required modules around it.

Main features I wanted this Board to have are,

Compatible with PIC16F and PIC18F family of microcontrollers

Incircuit programming capability

3.3V and 5V Power supply compatibility as per interface requirements

RS232 Debugging capability

3.3V or 5V serial Connectivity to Interface with another microcontroller

Power good indicator

USB Powerup or external powerup options

ICSP Debugging option

Onboard Test Leds

Individual GPIO hardware connectivity for flexible external custom circuit interface

CIRCUIT & PCB DESIGN - USING EAGLE

Schematic Design and PCB was developed using EAGLE CAD, The following shows screenshots shows the various stages of development

 

Starting with the Microcontroller and its GPIO..

 

Progressing with the ICSP and power circuits..

 

The completly finshed PCB

 

MODELLA - PCB MILLING

The finished milled PCB, ready to be cut and removed

 

The finished PCB..

 

Assemblying the components..

 

This is a closer view of the tracks of the PCB, I was not satisfied with the tracks from Microcontroller, it doesnt seem to have got milled properly and I decided to quit trying to fix the controller directly to avoid problems that may arise later..

 

I did not want to throw this PCB away and hence decided to use SMD To DIP adapter and solder the PINS to the corresponding tracks of the mother board..

 

Wires fixed to the pins of DIP adapter..

 

Adapter PCB with the microcontroller soldered to it, ready to be fixed to the motherboard..

 

Though it felt simple, it wasnt that easy to solder all the wires.. it took a while for me to get them soldered.. well no giving up!!

 

Finally I completed the connections and after a thorough checkup, I powered on the board using external USB connector..

 

It was time to check one of the critical things, the ICSP connectivity.. well to my goodfortune that too got worked the very first time..My programmer could detect the PIC16F877A.. finally a great relief to the hectic soldering :)

 

LCD INTERFACING

I am interfacing a 20 Character 4 line LCD based on Hitachi HD44780 LCD controller..

 

Rear view of the LCD module..

 

Resistor connected to control the contrast of the LCD module on PIN NO3. I have used nibble mode for communication.

 

A closer look at the microcontroller side for interfacing. This time the board is working on 5V mode..

 

I have used PICC compiler for writing the LCD interface program, the following is a screenshot of the same..

 

I didnt had much trouble in getting the LCD worked, the following shows the output. I did not use the backlight to avoid overloading the programmer with higher current consumption..

 

The design files can be downloaded from here.

OTHER OUTPUT DEVICES

For this weeks assignment I am only using an LCD module as my output device. But other than this I have tried to use ESP8266 WiFi module as an output module, which is to be used in my final project. A detailed documentation will be included with the final project documentation on this.

ANALOG & DIGITAL OUTPUTS

Talking from the perspective of Sensors, it usually output one of the two types of signal. An Analog signal or a Discrete signal.

Analog signals are continuous in time and the value for these signals exists for every moment of time. Digital signals are continuous in time just like analog signals but they have fixed values or states. The signal is defined at every moment of 't', but they have fixed states or values either 1 or 0.