Electronics – Andromedabay Store

Controlling 1.54 inch E-Paper via Pico

Hammad Rauf — Sun, 26 Jun 2022 18:12:41 +0000

Read Time:2 Minute, 50 Second

The original Kindle made popular Electronic Paper Displays (EPD). Today you may be surprised to find out that some grocery stores use small network enabled EPD price tags, that appear just like a paper tag. But these can be programmed to show different price remotely. Perhaps the biggest advantage to EPD is that once a display is setup they do not need any electrical power to keep showing it. Yes, you can switch off or disconnect them.

EPD have disadvantages also. These include that they are slow to refresh the display, cannot be used out doors for a long time, and have limited color options in the market.

I wanted to make a small micro controller based device that would need a display and also consume less electrical power. I ordered a 1.54 inch EPD from Waveshare. My original plan was to use Arduino Nano (ATMega32P) based solution, but I found out that I could not connect the e-paper display and a couple of other peripherals to Arduino, all at the same time. I did not need Wifi or Network connectivity for the application in my mind. So I opted for Raspberry Pi Pico (Based on RP2040). Pico is low cost, you should be able to get it for CAD$5.25 but the cost of shipping and tax added I ended up ordering it from AliExpress as it was more economical.

Waveshare website have very good documentation and code examples for most of their products. Unfortunately for me, the 1.54 inch EPD did not have any ready made examples to go with Pico. Luckily I found Waveshare Pico code for their other EPD, with this along with 1.54 inch EPD code for RaspberryPi_JetsonNano, I was able to get Pico to control it. I have uploaded the result on Github for others using Pico with 1.54inch EPD. It is using C/C++ and can be cross compiled for Pico on Windows, Linux, or a Raspberry Pi computer.

What is the fun part? You can do embedded C/C++ programming in Windows 10 or 11. On my Github page and in the reference links below you will find interesting information on how to use Windows Sub System for Linux (WSL2) for programming the Micro controller in C/C++.

Video

Setup a Cost Effective Web Site

Hammad Rauf — Sat, 21 Aug 2021 21:54:13 +0000

Read Time:3 Minute, 3 Second

Many people pay hefty monthly subscription fees to have a Website for their Business or Personal use. It is possible to setup up a functional website in your home or small business office in a cost effective way. It will save you money in the long run, and you have total control over the site. The only catch is that you (or someone in your home/team) will have to be a little tech savvy.

Raspberry P i is a small Single Board Computer (SBC), which is available in different forms for low prices, some as low as US$ 10. These articles will particularly be referring to Raspberry Pi 2B that sells for US$ 35. Your circumstance may lead you to more expensive setup. I would also be using an USB Thumb Drive (16GB), that costs about US$ 8 on Amazon. Almost all homes and small offices already have an Broad-Band Internet connection, so I will not factor in that cost. Plus there will be a cost for the Wall Adapter, Case, SD Card and Heat Sink.

One of Raspberry Pi 2B, Raspberry Pi 3B or Raspberry Pi 4B
Heat Sink (Optional for 2B)
A Plastic or Aluminum Case for your Model of Raspberry Pi
Wall Power Adapter
SD Card (8 GB or higher)
USB Thumb Drive (16 GB)
Internet Connection: Connected 24 Hours 7 days a Week – Minimum Download speed of 50 Mbps, Minimum Upload speed of 50 Mbps.

[CP_CALCULATED_FIELDS id=”6″]

So your total lifetime expense for the Web-Site will be at the least US$ 80, using free versions of most software items. For a faster site you may opt for Raspberry Pi 4B 8 GB Model but that is a bit more expensive then the other models. You may also opt for paid domain names, non-free SSL Certificates, and paid versions of WordPress-plugins, those will be extra costs if you go that path. In this series of articles we will be using free versions of what ever is possible, if you want you can replace those items with paid versions later on.

The beautiful thing about Raspberry Pi is that it is very quite (usually no fan coolers), consumes very little electrical power (Pi 2B needs 2 Amperes at 5 Volts = 10 Watts). In this Web-Server use-case it does not need a Monitor screen to run, it can run headless. You can use you MacBook, Laptop or Desktop to configure or monitor it via network connection using SSH Protocol.

This series of articles will guide you through to set up a WordPress Site on your Raspberry Pi. WordPress is a very popular Open-Source, Blogging Application written in PHP Programming Language, designed to run on a Web Site Server. Over the years it has seen many Plugins developed for it and a huge community of developers, vendors and users . WordPress is also used to sell products, services, and many Shopping-cart plugins are available for it. Many web sites around the world are executing in WordPress Application in the background.

This series of articles will be made up of the following parts:

Part 1 – Setup the Pi (Coming Soon)

Part 2 – Install Apache2 – (Coming Soon)

Part 3 – Install PHP – (Coming Soon)

Part 4 – Install MariaDB/MySQL – (Coming Soon)

Part 5 – Setup Domain Name – (Coming Soon)

Part 6 – Obtain and Install SSL Certificate – (Coming Soon)

Part 7 – Install WordPress – (Coming Soon)

Part 8 – Basic Configuration and Security in WordPress – (Coming Soon)

Part 9 – Secure Raspberry Pi with fail2Ban – (Coming Soon)

Part 10 (Bonus) – Setup Private DNS Server – Having multiple sites in Apache – (Coming Soon)

Part 11 (Bonus) – Backup and Remote Private Cloud Sync – (Coming Soon)

Part 1 – Setup the Pi – Cost Effective Web Site Series

Hammad Rauf — Sat, 21 Aug 2021 21:51:48 +0000

Read Time:2 Minute, 16 Second

(This article is a work in progress – Please do re-visit later when it has been completed).

This is the first part of the article series about setting up a cost effective web site in your home or small business office.

To start with you need to have the following items:

One of Raspberry Pi 2B, Raspberry Pi 3B or Raspberry Pi 4B
Heat Sink (Optional for 2B)
A Plastic or Aluminum Case for your Model of Raspberry Pi
Wall Power Adapter
SD Card (8 GB or higher)
USB Thumb Drive (16 GB)

In this article we will look at how to prepare the SD-Card for initial boot. Then we will connect to raspberry pi using SSH protocol. Then we will assign fixed IP address to Wired and Wifi network settings. Then we will prepare the USB thumb drive for use with raspberry pi. After that we will mount the USB thumb Drive to a fixed location so even if we unplug and re-plug the USB drive or if the Pi is rebooted, it automatically re-mounts to the same location every time, as long as the USB drive is not re-formatted.

Download the Operating System (OS)

The Raspberry Pi can run different operating systems some of which may not be listed on the official Pi Operating Systems page. This series of articles will be giving instructions for the official OS for Raspberry Pi only, the “Raspberry Pi OS” also known as “Raspbian”. You can download the OS from the Official Page. You can download any of the following:

Raspberry Pi OS with Desktop and software
Raspberry Pi OS with Desktop
Raspberry Pi OS Lite

The first 2 options use more SD Card space and include a Graphical User Interface (GUI). But since we plan to use our Pi as a “headless” server without a directly connected monitor – it may improve response time of your Pi, if you do not use one of the first two. The 3rd option (Raspberry Pi OS Lite), if you do not plan to use the GUI, will take less space on the SD Card, and may give better response times. I will try to provide all the commands that we will need in these articles. On my Raspberry Pi I have installed the 2nd option “Raspberry Pi OS with Desktop” as I do sometimes connect a monitor or use VNC Viewer for a remote GUI Desktop session.

Copy the OS to SD Card

Prepare SD Card for first boot

a. Enable SSH

b. Setup Wired (Ethernet) Connection IP Address

c. Setup Wifi Connection (if needed)

Initial Login

Prepare USB Thumb Drive

a. Format as ext4 format (recommended)

b. Format as FAT32 (if desired)

Setup USB Mount in Pi “fstab” file

Controlling Servo Motor with a Knob and a Limit

Hammad Rauf — Sun, 01 Oct 2017 15:42:26 +0000

Read Time:3 Minute, 45 Second

Arduino Uno and Arduino Nano are two of most extensively used hobby micro-controller boards. I found a web article about controlling a servo motor with a knob (Potentiometer, or Pot) , given here. Since I had a Pot lying around and had ordered cheap clone of Uno and Nano from Aliexpress.com, I thought it would be a great learning opportunity for my son (Grade 8) to see it built.

The original article describes exactly what is needed. It uses Uno, that I replaced with Nano. I could use the same pin numbers on Nano as in the original article. The original code allows one to control the servo motor which can move in both directions clockwise and anti-clockwise in unlimited rotation.

Arduino IDE is an easy to use editor and compiler for Arduino and compatible products. For download link please see the Further Reading section below. Here is a link for a good article on how to get started with Arduino IDE.

Hardware Required

Arduino Uno or Nano Board
Servo Motor (Continuous rotation type used here)
10k ohm potentiometer
hook-up wires
A Computer with USB Port (For running Arduino IDE)
Bread Board (Optional)
A 5 Volt Power Bank (Optional – For running the circuit independent of the computer)

Adding A Limit To Servo Rotation

The program given in the original article is very good. My modification to the C program introduces a limit on the rotation of the Servo. The idea is where ever this code is used, it will be physically limited. For example, there will be limit on servo movement because of length of the screw a servo is turning.

I have also added some Print statements to allow us to debug and calibrate your particular servo motor. The output of these print statements can be seen on the Serial Port Listener window in Arduino IDE.

Code Listing

/*
Controlling a servo position using a potentiometer (variable resistor)
by Michal Rinott 

modified on 8 Nov 2013
by Scott Fitzgerald
http://www.arduino.cc/en/Tutorial/Knob

modified on Sept 29, 2017
by Hammad Rauf
*/

#include 

Servo myservo; // create servo object to control a servo

int potpin = 0; // analog pin used to connect the potentiometer
int val; // variable to read the value from the analog pin
const int P_LIMIT = 2000; // One directional rotation Maximum Limit
const int N_LIMIT = -2000; // One directional rotation Maximum Limit
int cur_location = 0; // Current location of Maximum Limit
int midp = 0; // Value from mid point of 0 to 180 ie 90, as mid point.
const int my_motor_mid = 5; // Servo variance actual mid point is at 95.

void setup() {
	myservo.attach(9); // attaches the servo on pin 9 to the servo object
	Serial.begin(9600);
	Serial.println("Arduino Knob with Limit - Debug");
	delay(2000);
}

void loop() {
	val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)
	val = map(val, 0, 1023, 0, 180); // scale it to use it with the servo (value between 0 and 180)
	midp = val - 90;
	if ((midp) >= 0) {
		if (cur_location <= P_LIMIT) {
			cur_location += midp;
		}
	}
	else {
		if (cur_location >= N_LIMIT) {
			cur_location += midp;
		}
	}
	Serial.print("midp=");
	Serial.print(midp);
	Serial.print(", cur_location=");
	Serial.println(cur_location);
	if ((cur_location >= N_LIMIT) && (cur_location <= P_LIMIT)) {
		//Serial.println("Inside-1");
		myservo.write(val); // sets the servo position according to the scaled value
		delay(15); // waits for the servo to get there
	}
	else {
		//Serial.println("Inside-2");
		myservo.write(my_motor_mid + 90); // sets the servo position to mid point
		delay(15); // waits for the servo to get there
	}
}