Arduino OLED clock plus thermometer

Organic light-emitting diode (OLED) displays are the coolest displays ever made. Check out this instructable on building an Arduino controlled OLED clock that uses a DS3231 RTC module for precise time-keeping. The DS3231 is a low-cost, extremely accurate I2C realtime clock (RTC) with an integrated temperature compensated crystal oscillator (TCXO) and crystal. The project incorporates a rechargeable battery to maintain accurate timekeeping during power failure. The implementation of an interactive menu system, which is navigated through two tact switches, the time setting becomes handy. The DS3231 module uses the built-in temperature sensor to compensate for clock drift due to temperature variation, which helps to keep the accuracy to 1 or 2 minutes/year. By default, the temperature is sensed and updated by the DS3231 once every 64 seconds. However, it is possible through software to update temperature reading and oscillator adjustment done as fast as 5 times/second. The temperature measurements are also displayed on the OLED clock screen. The author uses Adafruits Graphics library to drive the OLED display, which has the SSD1306 controller.

Arduino OLED clock

Arduino OLED clock

Portable GPS logger for runners

Daniel’s portable GPS logger is a university-funded project and is geared towards runners to record their movement. The core hardware of the project mainly consists of an LPC1778 Cortex M3 microcontroller, an Adafruit Ultimate GPS module, and a Newhaven Display 2.4″ ILI9340 QVGA LCD, which are all powered by a 500 mAh Lithium Ion battery.The GPS logger circuit also contains an on-board batter charger circuit using Microchip MCP73831T IC. It displays the current distance traveled and the time taken to travel the distance. The maps are generated from TileMill using a custom color scheme and OpenStreetMap data, and are stored in a microSD card.

The electrical hardware design (schematic/layout) and software for this GPS logger can be downloaded from GitHub.

Portable GPS logger for runners

Portable GPS logger for runners

[Via Hackaday]

STM32 Internals

STM32 micros as we know are high-end micros and this high-end tag is not only due to its memory, speed and hardware richness. An advanced micro like this also needs advanced internal supporting hardware. Most of us know about watchdog timers from previous experiences with common 8 bit MCUs like AVR and PIC. However when it comes to STM32 the idea of watchdog circuitry is elaborated. The options available for clock are also enhanced in the STM32 micros. In this post, we will see some of these supporting internal hardware. We will examine the use and operation of two different watchdog timers – Independent Watchdog (IWDG) and Window Watchdog (WWDG), and the clock options usually found in common STM32 micros.

Clock Options

In a robust microcontroller like the STM32 there are several options for clock. At first the whole stuff may look a bit complex. Indeed it is complicated but not too difficult to understand. The simplified block diagram below shows the common clock arrangement inside a STM32F103 series MCU.

Clock Internal

STM32F103 Internal Clock Arrangement (Source: The Insiders Guide to the STM32 ARM based Microcontroller from HITEX, http://www.hitex.com/fileadmin/pdf/insiders-guides/stm32/isg-stm32-v18d-scr.pdf)

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Turn-taking logger

Conversation analysis (CA) is a disciplined approach of studying natural conversations to understand how participants interact and respond in their turns at talk. The input data for CA is derived from audio or video recording of naturally occurring talk. Turn-taking is considered to be the basic unit of speech in CA. Rachel Yalisove has posted a new instructable about her turn-taking logger, an Arduino-controlled device to monitor and record  turn-takings in a 2-person conversation. The project uses two electret microphone modules with on-board amplifiers to sense the audio levels of the two persons participating in the conversation. The two microphone outputs are continuously monitored through two ADC channels of the Arduino board, which then differentiate between the speaker and hearer by comparing the two outputs. The length of each turn is computed using a timer routine. The turn-taking logger writes out these measurements in a text file on an SD card. A push switch is used in the project to control record and stop operation, while two LEDs are used to give a visual indication of who is talking at any particular moment.

A very simple turn-taking logger for CA

A very simple turn-taking logger for CA

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