Displaying Cyrillic fonts on a 128x64 OLED display

Electronics

Recently I picked up a couple inexpensive 128x64 pixel OLED displays with an I2C interface. It turns out that displaying Russian text on these displays is not difficult. But it’s non-obvious. This is a brief description of how to make it work.

First, there’s a variety of these little displays and they’re all seemingly configured a little differently. I used this device for this test.

There are two options for libraries to simplify communicating with SSD1306 boards:

The u8g2 library has a much more robust mechanism for selecting fonts, so that’s what I used.

Here’s the code in full:

#include <Arduino.h>
#include <U8g2lib.h>

#ifdef U8X8_HAVE_HW_SPI
	#include <SPI.h>
#endif
#ifdef U8X8_HAVE_HW_I2C
	#include <Wire.h>
#endif

/*
    Illustrating the use of cyrillic text on the 128x64 OLED display
*/
U8G2_SSD1306_128X64_NONAME_F_SW_I2C u8g2(U8G2_R0, SCL, SDA, U8X8_PIN_NONE);

void setup(void) {
	u8g2.begin();
	u8g2.enableUTF8Print();        // enable UTF8 support for the Arduino print() function
}

void loop(void) {
	// select a font with 11px height
	u8g2.setFont(u8g2_font_cu12_t_cyrillic);
	u8g2.firstPage();
	do {
		u8g2.setCursor(0, 40);
		u8g2.print("Всем привет!");
		u8g2.setCursor(0,12);
		u8g2.print("Как у вас?");
	} while ( u8g2.nextPage() );
}

References

Reading data from Si7021 temperature and humidity sensor using Raspberry Pi

Electronics

The Si7021is an excellent little device for measuring temperature and humidity, communicating with the host controller over the I2C bus. This is a quick tutorial on using the Raspberry Pi to talk to this device. If you are unfamiliar with the conceptual framework of I2C or how to enable I2C access on the Raspberry Pi, I suggest starting here. Otherwise, let’s jump in.

You are probably working with the device mounted on a breakout board. I used this one from Adafruit. There are no surprises on the pins that it breaks out - Vin, 3v out, GND, SCL and SDA. One the 40-pin P1 header of the Raspberry Pi, SDA and SCL for I2C bus 1 occupy pins 2 and 3.

Read more…

RF communication between Arduino Nanos using nRF24L01

Electronics, Wireless

In this tutorial I’ll go through a simple example of how to get two Arduino Nano devices to talk to one another.

Materials

You’ll need the following materials. I’ve posted Amazon links just so that you can see the items, but they can be purchased in a variety of locations.

  • Arduino Nano 5V/16 MHz, or equivalent (Amazon)
  • Kuman rRF24L01+PA+LNA, or equivalent (Amazon)

About the nRF24L01+

The nRF24L01+ is an appealing device to work with because it packs a lot of functionality on-chip as opposed to having to do it all in software. There is still a lot of work to be done in code; but it’s a good balance between simplicity and functionality. It’s also inexpensive.

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Using the Raspberry Pi to communicate over the I2C bus using C

Electronics
I recently wrote about using the excellent bcm2835 library to communicate with peripheral devices over the SPI bus using C. In this post, I’ll talk about using the same library to communicate over the I2C bus. Nothing particularly fancy, but you’ll need to pay careful attention to the datasheet of the device we’re using. TheTSL2561 is a sophisticated little light sensor that has a very high dynamic range and is available on a breakout board from Adafruit. I’m not going to delve into the hookup of this device as you can take a look at the Adafruit tutorial for that. Note that we’re not going to use their library. (Well, I borrowed a bunch of their #define statements for device constants.)
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Implementing ADC using Raspberry Pi and MCP3008

Electronics

Several years ago I wrote about adding analog-to-digital capabilities to the Raspberry Pi. At that time, I used an ATtinyx61 series MCU to provide ADC capabilities, communicating with the RPi via an I2C interface. In retrospect it was much more complicated than necessary. What follows is an attempt to re-do that project using an MCP3008, a 10 bit ADC that communicates on the SPI bus.

MCP3008 device

The MCP3008 is an 8-channel 10-bit ADC with an SPI interface^[Datasheet can be found here.]. It has a 4 channel cousin, the MCP3004 that has similar operating characteristics. The device is capable of performing single-ended or differential measurements. For the purposes of this write-up, we’ll only concern ourselves with single-ended measurement. A few pertinent details about the MCP3008:

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2018: Experiment No. 1

Self-Improvement

2018 is my year of experiments (Why? TL;DR: New Year’s resolutions are over-rated and have a high failure rate. Anyone can run an experiment for a month.) My first experiment (No news for a month) is nearly done and I’ll declare it a success.

Background

The round-the-clock sensational news cycle exists in large part to create wealth for the already-too-wealthy. Little of it is actionable, leaving us at the same time both outraged and impotent. Mostly I decided to give up on the news because of Donald Trump, the demented psychopathic moron who managed to get elected president.^[I use these terms very carefully. Many have speculated that he suffers from some form of dementia owing to events where he slurs his words and perseverates. His sociopathic or psychopathic behaviours are well-documented; he is man devoid of empathy. And finally, his lack of reading is well-known. For all I can tell, the man is a functional illiterate. In contrast, his predecessor is a bibliophile and read widely and voraciously throughout his tenure.] Since Trump took office, like others, I’ve found myself cycling repeatedly through the stages of grief. But mostly I’ve been stuck on anger. There’s something about willful ignorance that does that to me.

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2018: A year of experiments

Self-Improvement

New Year’s resolution time is at hand. But not for me; at least not in a traditional sense. I was inspired by David Cain’s experiments. In short, he conducts monthly experiments in self-improvement.

The idea of an experiment is appealing in ways that a resolution is not. A resolution presumes an outcome and relies only on the long application of will to see it through. An experiment on the other hand, makes only a conjecture about the outcome and can be conducted for a shorter period.

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