Tag Archives: Low Power

LPC55S16-EVK: how fast does it go? How much current does it take?

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I will always take the same approach when I receive a new embedded board: firstly I want to see how quickly I can get it up-and-running, then I want to see what it does “out-of-the-box” and finally I want to find out if the board is “useful”. Does it have some features that will inspire me for new projects??

The NXP LPC55S16-EVK has some great features – CAN-FD, dual USB and a high performance Cortex M33 microcontroller, running at 150 MHz. I have an idea to use the LPC55xx series as the basis for a Weather Station. But this is only feasible if the chip has a low power consumption and can run for weeks on a small battery.

Time to run some test code and get my digital multimeter out…

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FreeRTOS: how to End and Restart the Scheduler

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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:

coverage information from freertos application

coverage information from FreeRTOS application

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 …

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Upgrading to Sharp 128×128 Pixel Memory Display

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In “Low Power LCD: Adafruit Breakout Board with Sharp Memory Display” I used a 96×96 Sharp Display (LS013B4DN04) with the Adafruit breakout board, but because that one seems to be EOL (End Of Life), I searched for a replacement. I have found the 128×128 pixel version (Sharp LS013B7DH03), and best of all, it is pin compatible :-). With a small tweak of the driver, it works :-):

Sharp Memory Display 128x128

Sharp Memory Display 128×128

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Low Power LCD: Adafruit Breakout Board with Sharp Memory Display

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Many projects benefit from a small display as a user interface. For very low power applications this is usually a no-go as the display needs too much energy. I have used e-paper displays from Kent: while these e-paper displays do not need any power to keep the image, changing the display content is not for free, plus is very slow (around 1 second needed to update the display). So I was looking for something low power and fast for a long time, until Christian (thanks!) pointed me to a display from Sharp: both very low power and fast:

Font Test with Sharp Memory Display

Font Test with Sharp Memory Display

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