NXP LPC17xx/40xx: Decoding the Part ID
Richard Bennett explains how the LPC17xx/40xx part ID is not a simple model number but a packed set of capability flags. The post shows how to call the NXP IAP routine at 0x1FFF1FF1 with command 54 to read the part ID, and how to decode family, group, RAM, flash and feature bits with shifts and masks, including the important interrupt-disable gotcha.
SIGFOX – A new network technology for IoT comms?
Built for tiny, infrequent messages, SIGFOX promises ultra-low-cost, long-life IoT connectivity using ultra-narrowband radios and a managed back-end. The network supports 12-byte uplinks, up to 140 messages per day, deep indoor penetration, and multi-year battery life, making it ideal for meters, alarms, and simple sensors. The article covers coverage, available modules, and practical trade-offs like limited bandwidth and vendor lock-in.
Practical CRCs for Embedded Systems
Stephen Friederichs shows a practical way to get correct CRC code quickly by using PyCRC to generate C implementations, then verifying them on the desktop and an AVR ATMega328P. The post walks through the common generation algorithms, how to self-test with the standard "123456789" check value, and a real timing comparison that exposes the speed versus memory tradeoffs for embedded systems.
The CRC Wild Goose Chase: PPP Does What?!?!?!
Jason Sachs walks through a CRC rabbit hole and explains why ambiguous CRC names and incomplete specs lead to subtle protocol bugs. He demonstrates how XMODEM and KERMIT variants with a zero initial value can miss dropped leading-zero bytes, praises the X.25 standard for providing test vectors and a clear CRC16 definition, and warns that RFCs that ship only sample code are a poor substitute for a proper specification.
OOKLONE: a cheap RF 433.92MHz OOK frame cloner
Fabien Le Mentec built a pocket device that listens to and clones 433.92MHz OOK frames, automating the tedious reverse engineering of cheap wireless outlets. The prototype uses a Moteino with an RFM69 to sample demodulated OOK data, stores pulse durations in SRAM, and replays frames; the code and hardware notes are available on GitHub along with limitations and next steps.
Reverse engineering wireless wall outlets
Fabien Le Mentec reverse engineers a cheap set of wireless wall outlets to add them to his BANO home automation while avoiding uncertified mains hardware. He uses PCB inspection to identify a Holtek MCU and RF83C, captures 433.92 MHz OOK signals with an RTL-SDR and ookdump, then replays commands using an RFM22 in direct mode controlled by an ATmega328P. The post explains frame structure and links to a working GitHub implementation.
A wireless door monitor based on the BANO framework
Fabien Le Mentec built a battery-powered wireless door monitor and a reusable node framework called BANO to monitor doors across seven floors without wired links. The post highlights BANO's 17-byte key,value protocol, the node runtime that enables wake-on-interrupt low-power operation, and practical RF choices like the NRF905 plus a 330 µF cap to handle coin-cell transmission peaks. It includes source, PCB, and base station notes.
April is Oscilloscope Month: In Which We Discover Agilent Offers Us a Happy Deal and a Sad Name
Jason Sachs grabbed an MSOX3034 during Agilent's bandwidth deal, used a 30-day trial to debug UART issues, and then discovered Agilent's 'Happy Deal' lets you enable all MSOX software for the price of a single option. He walks through which MSOX3000 modules are worth buying, explains memory and waveform features, and delivers a wry take on the company's new Keysight name.
Using a RTLSDR dongle to validate NRF905 configuration
Fabien Le Mentec wanted to be sure his nRF905 radio link was configured correctly before trusting it across seven floors. Instead of guessing, he used a cheap RTLSDR dongle, rtl_fm, and a small custom decoder to inspect the 433 MHz traffic directly. The result was a practical way to validate packet framing, Manchester coding, and signal strength without relying only on the radio module’s own feedback.
Introduction to Microcontrollers - Driving WS2812 RGB LEDs
Mike Silva walks through a practical, cycle-counted AVR assembly implementation to bit-bang WS2812B RGB LEDs from an 8MHz AVR, hitting the chip's tight 1.25µs-per-bit timing. The post breaks down the WS2812B self-clocked protocol and GRB byte order, explains register and calling-convention choices, and includes a complete C example plus power-consumption warnings for driving LED strips.
Real-time clocks: Does anybody really know what time it is?
Most RTC chips still expose calendar fields rather than seconds-since-epoch, forcing embedded engineers to write ugly conversion code. Jason Sachs makes the case for offset encoding, subseconds, and an explicit snapshot feature to simplify interval math, raise precision, and avoid rare timing bugs. Read this practical take on RTC trade-offs and a short wishlist for chip makers.
Racing to Sleep
Jason Sachs walks through a realistic field sensor case study, the BigBrotherBear 2000, to show how a careful power budget exposes surprising energy costs. He demonstrates that radios and data transmission often dwarf quiescent MCU current, explains the race-to-sleep principle for computation-bound tasks, and outlines practical wake-up and measurement trade-offs so engineers can extend battery lifetime in real deployments.
Using (Apache) NuttX USERLED Subsystem
Controlling an LED with raw GPIO works, but NuttX's USERLED subsystem makes it cleaner and portable. This post walks through enabling the LED driver in menuconfig, mapping the RaspberryPi Pico LED in the board files, and using the /dev/userleds device with printf to set up to 32 LEDs with a single write. It finishes with a hands-on challenge to expand the setup to eight LEDs on a breadboard.
How to use SPI devices in NuttX RTOS
You can get an SPI sensor running on NuttX in minutes by following a concrete RP2040 example. This post walks through the board glue code, Makefile and header edits, menuconfig settings, wiring, and flash steps needed to register a MAX6675 thermocouple on a Raspberry Pi Pico. Read it to learn where to add board-level code, enable drivers, and test the device from NSH.
How to Give Persistent Names To USB-Serial Devices on Ubuntu 14.04
When your dock reshuffles ttyUSB assignments, Tayyar shows how to bind USB-serial devices to persistent names on Ubuntu 14.04. The post walks through using dmesg and udevadm to locate unique attributes like KERNELS and ATTRS{serial}, creating /etc/udev/rules.d entries with NAME and SYMLINK, and applying rules with udevadm trigger. It includes common pitfalls and quick fixes to get minicom talking to the right port.
Linear Feedback Shift Registers for the Uninitiated, Part XII: Spread-Spectrum Fundamentals
Jason Sachs shows why LFSR-generated pseudonoise is a natural fit for direct-sequence spread spectrum, then walks through Fourier basics, spectral plots, and runnable Python examples. The article demonstrates how DSSS multiplies a UART bitstream with a chipping sequence to spread energy, how despreading concentrates the desired signal while scrambling narrowband interference, and how multiple transmitters can share bandwidth when using uncorrelated sequences.
Using (Apache) NuttX Buttons Subsystem
You do not need to poke GPIO registers to read switches in NuttX, the OS provides a Buttons subsystem that delivers named events, multi-button support, and optional software debouncing. This post walks through wiring two breadboard buttons on a Raspberry Pi Pico, enabling the input and buttons drivers via menuconfig, building nuttx.uf2, and testing the buttons over the usbnsh serial console. It highlights why a simple hardware debounce is still a good idea.
April is Oscilloscope Month: In Which We Discover Agilent Offers Us a Happy Deal and a Sad Name
Jason Sachs grabbed an MSOX3034 during Agilent's bandwidth deal, used a 30-day trial to debug UART issues, and then discovered Agilent's 'Happy Deal' lets you enable all MSOX software for the price of a single option. He walks through which MSOX3000 modules are worth buying, explains memory and waveform features, and delivers a wry take on the company's new Keysight name.
Designing IoT Wireless Sensor Nodes
Mahesh Balan outlines practical strategies for building tiny IoT wireless sensor nodes that run on harvested energy. The post explains using small solar cells with coin-cell or supercapacitor buffering, pairing sensors with Bluetooth Low Energy for short-range telemetry, and choosing PMICs with ultra-low quiescent and startup power. A Cypress PMIC example shows operation can be sustained under low-brightness conditions near 100 lx.
How 5G impacts future IoT development
The Internet of Things (IoT) applications are ubiquitous today. IoT is used in almost every industrial, commercial, and consumer market segment, including autonomous driving, smart factories, automation and preventive maintenance, smart homes, smart cities, security, asset tracking, supply chain management, agriculture, farming, healthcare, smart medicine and remote surgery, augmented reality applications, activity monitoring, and more. The three most promising uses of IoT are smart manufacturing, autonomous driving, and healthcare, particularly remote surgery.
Using GPIO in (Apache) NuttX RTOS
Blinking an LED is the embedded Hello World, and this tutorial walks through using GPIOs on NuttX running on a Raspberry Pi Pico. It shows how to enable the GPIO driver and example in menuconfig, build and flash the nuttx.uf2, and use NSH gpio device files to read and write pins. The post also explains polling versus interrupt-driven inputs and the pull-up/edge setup needed for button interrupts.
A simple working I2C (TWI) level shifter
When interfacing 3.3V and 5V boards, Dr Cagri Tanriover shows a no-fuss MOSFET solution to keep I2C talking across voltages. The post walks through using the NXP MOSFET level-shifter idea with BS170 transistors and 10 kΩ pull-ups, notes it ran at 400 kbps for his setup, and includes a quick four-step test to verify the build before connecting microcontrollers.
Get your microcontroller and PC to talk
Projects often need a quick PC interface for an otherwise standalone microcontroller, but learning VB or Visual C++ can feel like overkill. Jayaraman Kiruthi Vasan shows how Processing, an open source, C like environment with serial and Arduino libraries, gives embedded engineers a fast, low friction way to build GUIs and COM links to chips like the 8051 and Renesas R8C. The post promises a hands on example connecting Processing to a 8051.
Picowoose: The Raspberry Pi Pico-W meets Mongoose
This example application describes the way to adapt the George Robotics CYW43 driver, present in the Pico-SDK, to work with Cesanta's Mongoose. We are then able to use Mongoose internal TCP/IP stack (with TLS 1.3), instead of lwIP (and MbedTLS).
April is Oscilloscope Month: In Which We Discover Agilent Offers Us a Happy Deal and a Sad Name
Jason Sachs grabbed an MSOX3034 during Agilent's bandwidth deal, used a 30-day trial to debug UART issues, and then discovered Agilent's 'Happy Deal' lets you enable all MSOX software for the price of a single option. He walks through which MSOX3000 modules are worth buying, explains memory and waveform features, and delivers a wry take on the company's new Keysight name.
When a Mongoose met a MicroPython, part I
This is more a framework than an actual application, with it you can integrate MicroPython and Cesanta's Mongoose.
Mongoose runs when called by MicroPython and is able to run Python functions as callbacks for the events you decide in your event handler. The code is completely written in C, except for the example Python callback functions, of course. To try it, you can just build this example on a Linux machine, and, with just a small tweak, you can also run it on any ESP32 board.
How to use SPI devices in NuttX RTOS
You can get an SPI sensor running on NuttX in minutes by following a concrete RP2040 example. This post walks through the board glue code, Makefile and header edits, menuconfig settings, wiring, and flash steps needed to register a MAX6675 thermocouple on a Raspberry Pi Pico. Read it to learn where to add board-level code, enable drivers, and test the device from NSH.
SIGFOX – A new network technology for IoT comms?
Built for tiny, infrequent messages, SIGFOX promises ultra-low-cost, long-life IoT connectivity using ultra-narrowband radios and a managed back-end. The network supports 12-byte uplinks, up to 140 messages per day, deep indoor penetration, and multi-year battery life, making it ideal for meters, alarms, and simple sensors. The article covers coverage, available modules, and practical trade-offs like limited bandwidth and vendor lock-in.
ANCS and HID: Controlling Your iPhone From Zephyr
In this blog post, we see how certain BLE services can be used to control an iPhone from a Nordic nRF52840 using The Zephyr Project. Specifically, we see how to control certain multimedia functionality using the HID service. Finally, we learn how to use the ANCS client library provided by Nordic in The Zephyr Project to accept or decline an incoming call.
When a Mongoose met a MicroPython, part II
In the first part of this blog, we introduced this little framework to integrate MicroPython and Cesanta's Mongoose; where Mongoose runs when called by MicroPython and is able to run Python functions as callbacks for the events you decide in your event handler. Now we add MQTT to the equation, so we can subscribe to topics and publish messages right from MicroPython.
