I really love tiny and bread board friendly boards, especially if they are very affordable and can be use with Eclipse based tools. So I was excited to see the NXP LPC845-BRK board to be available at Mouser, so I ended up ordering multiple boards right away. Why multiple? Because they only cost CHF 5.95 (around $6)!
In the age of high-resolution graphical LCDs using a character display might look like a bit anachronistic. But these displays provide a lot of value for me as they are robust, available in different shapes and number of lines. And such a character display can be a better solution for an industrial application.
It is a common thing to boot a Linux system (see the Raspberry Pi) from a micro SD card. It is not that common for a microcontroller. The NXP i.MX RT ARM Cortex-M7 fills that gap between these two worlds. No surprise that it features a ROM bootloader which can boot from a micro SD card.
Most host or desktop systems (say Linux, Mac or Windows) have a normal use case where you start the operating system say in the morning and shut it down in the evening, and then you leave the machine. Embedded Systems are different: they are not attended, and they are supposed to run ‘forever’. Not every embedded system needs to run an OS (or in that world: Real-Time Operating System or RTOS), but the same applies here: after the RTOS is started, it is not intended that it will shutdown and restart. To the extend that you won’t they support the ‘shutdown’ and ‘restart’ functionality at all. In case of gathering coverage information this would be really useful:
In the case of FreeRTOS: what if I really need to shutdown the RTOS and restart it again, as by default this is not supported. This is what this article is about …
GDB supports a mode which allows the GDB debug client to read memory while the target is running. This allows features like ‘live variables’: that way I can see the variables refreshed and changing over time without halting the target. Another functionality which comes with that feature is to check stopped threads or to see all threads in the system.
Modern microcontroller come with plenty of internal FLASH memory. On the other side, many high performance MCUs as the NXP i.MX RT are ‘flashless’, because the silicon process for high performance cores is not matching the FLASH memory technology, so they are using external serial SPI or Quad-SPI (QSPI) memory instead.
Why not using an external SPI FLASH for a ‘normal’ microcontroller too?
I’m using the VL6180X ToF (Time-of-Flight) sensors successfully in different projects. The VL6180X is great, but only can measure distances up to 20 cm and in ‘extended mode’ up to 60 cm. For a project I need to go beyond that, so the logical choice is the VL53L0X which measures between 30 cm and 100 cm or up to 200 cm. For this project I’m using the VL53L0X breakout board from Adafruit, but similar products are available e.g. from Pololu.
Working with low power modes can be challenging. It can severely affect debugging capabilities of a microprocessor or microcontroller. I ported a FreeRTOS application using the Tickless Idle Mode to the NXP i.MX RT1064 board, and all of a sudden, the board was unresponsive to any debugger connection. Luckily the board was not really bricked, but it took me while to find a way to recover it. So for when you end up in a situation with a ‘bricked’ i.MX RT1064 board, this article might be helpful for you to recover it.
I always reserve time between Christmas and New Year to get my hands on technology pieces which I might not have any time otherwise. Among different things I ordered the NXP i.MX RT1064-EVK board from Mouser.com, and it arrived right before Christmas. Time to have it unboxed and started….
You might wonder what ‘Zork‘ is? Zork is one of the first and earlist fictive computer games, written around 1977 and 1979, written in MDL on a DEC PDP-10 by members of the MIT Dynamic Modelling group (see https://en.wikipedia.org/wiki/Zork). I believe the first time I have played Zork was around 1984 on a Commodore 64.
With Eclipse as IDE it is very easy to debug an application on a board. Still sometimes it is useful to get one level down and control the GDB server directly.
Need a quick way how to attach a LED, a push button and two resistors to the Raspberry Pi header? One way is to use some ‘flying’ wires. Or to use three pieces of lasercut plywood for a nice looking Raspy extension board:
Unit testing is a common practice for host development. But for embedded development this still seems mostly a ‘blank’ area. Mostly because embedded engineers are not used to unit testing, or because the usual framework for unit testing requires too many resources on an embedded target?
What I have used is the μCUnit framework which is a small and easy to use framework, targeting small microcontroller applications.
Not ready for the complexity of a full blown Embedded Linux, but need that extra compute performance? Need an ARM Cortex-M7 running at 600 MHz module on a half-sized business card, ready to be integrated? Here we go: the Embedded Artists i.MX RT1052 OEM module:
Compute modules are very common in the Embedded Linux space, for example see this Toradex module. The reason is simple: these high-performance boards simplify the design, as I don’t have to care about the BGA packages and the external SDRAM and FLASH devices: everything is on a module I can easily integrate into my base board.
Open Source software has been around for decades. But open source on hardware especially microcontroller is not much a reality these days. But there is something which might change this: RISC-V is a free and open RISC instruction set architecture and for me it has the potential to replace some of the proprietary architectures currently used. RISC-V is not new, but it gets more and more traction in Academia (no surprise).
I wanted to play with RISC-V for over a year, but finally a week ago I did one of these “hey, let’s buy that board” thing again. Sometimes these boards get on a pile to wait a few weeks or longer to get used, but that one I had to try out immediately :-).
Most embedded projects need an user input device. For the NXP i.MX RT1050-EVK board I have recently added a 480×272 full color touch LCD (see “Adding a Rocktech Capacitive Touch LCD to the NXP i.MX RT1052 EVK“). I have looked at different commercially available GUI libraries, but none of them really were matching my expectations: either very expensive or closed source, or an overkill for small LCDs and projects. But then I have found LittlevGL: free-of-charge, open source, easy to use, well documented and has everything I need. And it really looks gorgeous 🙂
In my “Tutorial: Catching Rogue Memory Accesses with Eclipse and GDB Watchpoints” I have used Eclipse/CDT and GDB watchpoints. I used a conditional watchpoint, but this comes with a performance hit. In this article I show how to use the ARM Cortex trace hardware to catch specific writes to a memory location. Without severe performance degradation. But for this I need a little helper: the DEADBEEF catcher!
Powerful ARM Cortex-M7 microcontroller are on the rise, bridging the gap between traditional microcontroller and Embedded Linux systems. I already published articles for the NXP i.MX RT1052 which is an ARM Cortex-M7 running at 600 MHz. Because the RT105x is available in BGA196 package only, I have as oredered the i.MX RT 1050 EVK which has a similar device on it, but in LQFP package: