How to handle a DHT22 sensor using ARM mbed OS?

Published at August 1, 2017 · Michał Żygowski ·  8 min read

Recently I have encountered with temperature and humidity measurements using DHT22 sensor. I was developing a driver source code in ARM mbed OS SDK on particular STM32 NUCLEO L432KC platform. Thorough analysis of DHT22 documentation led me to the following questions: Is it possible to accurately measure voltage-level durations during read process? What duration time values should be considered as timeout or/and error? Should I weaken the time restrictions in order to avoid random delays in voltage level transitions be considered as failure?...

Categories: firmware iot

OpenOCD and development environment for Zephyr on NXP FRDM-K64F

Published at March 18, 2017 · Piotr Król ·  12 min read

In this post I would like to describe process of setting up NXP FRDM-K64F development environment under Linux and start Zephyr development using it. Why NXP FRDM-K64F ? I choose this platform mostly because of ready to use guide about using 802.15.4 communication by attaching TI CC2520, which was presented here. Typical wireless stack starts with 802.15.4, then 6LoWPAN adaptation and then IPv6, which carries application protocols. 6LoWPAN compress IPv6 so it can fit BLE and 802....

Categories: firmware iot

nRF51822 programming with OpenOCD under Linux

Published at January 22, 2017 · Kamil Wcisło ·  8 min read

Some time ago we bought BLE400 from Waveshare as probably one of the cheapest option to enter nRF51822 market. As our readers know, we prefer to use the Linux environment for embedded systems development. Because of that, we’re following the guide for using Waveshare nRF51822 Eval Kit: icarus-sensors. Kudos due to great post that helped us enter nRF51822 and mbed OS land under Linux. BLE400 is pretty cheap, because it hasn’t got integrated debugger/programmer....

Categories: firmware iot

Zephyr initial triage on Nucleo-64 STM32F411RE

Published at January 14, 2017 · Piotr Król ·  7 min read

As I mention in previous post Zephyr RTOS is an interesting initiative started by Intel, NXP and couple other strong organizations. With so well founded background future for this RTOS should look bright and I think it will quickly became important player on IoT arena. Because of that it is worth to dig little bit deeper in this RTOS and see what problems we faced when trying to develop for some well known development board....

Categories: firmware iot

Failure of ECC508A crypto coprocessor initial triage with SAM G55 Xplained Pro Evaluation Kit

Published at November 24, 2016 · Piotr Król ·  7 min read

Some time ago (around August 2016) embedded community media were hit with hype around simplified flow for AWS IoT provisioning (1, 2, 3). I’m personally very interested in all categories related to those news: IoT - is 3mdeb business core and despite this term was largely abused these days, we just love to build connected embedded devices. Building this kind of devices is inherently related with firmware deployment, provisioning and update problems....

Categories: firmware iot

Starting with Nucleo-F411RE and mbed OS for command line enthusiasts

Published at November 23, 2016 · Piotr Król ·  9 min read

When I first time read about mbed OS I was really sceptical, especially idea of having web browser as my IDE and compiler in the cloud seems to be very scary to me. ARM engineers proved to provide high quality products, but this was not enough to me. Then I heard very good words about mbed OS IDE from Jack Ganssle, this was still not enough. Finally customers started to ask about this RTOS and I had to look deeper....

Categories: firmware iot

SAMG55 + OLED1 Xplained Pro Hello World!

Published at October 20, 2016 · Piotr Król ·  4 min read

AMG55 - recognition in the field If you are considering working on SAMG55 Xplained Pro board here you will find some basic know-how to quickly get you started. What you will need? In this example I will be using SAMG55 Xplained Pro with OLED1 extension board, and Atmel Studio 7.0 with Data Visualizer addon, wich requires Windows to work. This however should be similar for other board with EDBG debugger....

Categories: firmware iot

Using PlatformIO with TI MSP430 LunchPads

Published at December 8, 2015 · Piotr Król ·  6 min read

PlatformIO is very interesting project that aim to solve very important problem of configuring deployment environment for embedded systems. IMHO good approach is to focus on modularity (various IDE can be used, even Vim) and simplicity (in best case 2 command should be enough to deploy first code). Recent years we have explosion of bootstraping applications (ie.vagrant, puppet). Most of them seems to follow git-like command line interface and getting a lot of attention from programmers community....

Categories: firmware iot

ESP-12 update to SDK v0.9.5 and AT v0.21.0.0? noobs tutorial

Published at January 25, 2015 · Piotr Król ·  5 min read

January 23th Espressif published new ESP IOT SDK on their forum v0.9.5. My ESP-12 came with with pretty old version so I decide to update it to latest one: 1 2 3 4 5 6 7 8 9 10 AT+RST OK y_RSöfJ[ú Version:] ready AT+GMR 0018000902-AI03 OK ESP-12 firmware update pin configuration As picture presents in addition to normal operation we have to pull down GPIO0 and pull up GPIO2....

Categories: firmware iot

Power on of ESP-12 (ESP8266)

Published at January 24, 2015 · Piotr Król ·  3 min read

ESP8266 is a SoC made by Espressif. For last couple of months this chip is a rockstar of HackADay and makers community around the Internet. Mostly because of WiFi modules built based on it (ESP-XX family). Rich interface (GPIO, SPI, SDIO, I2C) give those boards potential to be standalone MCU with WiFi capability for wide range of applications. In quantity you can get ESP-01 for $2.7 (for 1kpcs). Of course there is no free lunch....

Categories: firmware iot


2019 (12)
2018 (16)
2017 (12)
2016 (10)
2015 (8)
2014 (6)
2013 (14)
2012 (24)