Some ARM Cortex-M have a DWT (Data Watchpoint and Trace) unit implemented, and it has a nice feature in that unit which counts the execution cycles. The DWT is usually implemented on most Cortex-M3, M4 and M7 devices, including e.g. the NXP Kinetis or LPC devices.
DWT Cycle Count Register (Source: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0489d/BABJFFGJ.html)
I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge, with the following main features and changes:
SourceForge
When working and debugging a bootloader, debugging can be a challenge: During debugging the bootloader, a new binary gets loaded into the microcontroller address space which is unknown to the debugger. As soon as I step into the newly loaded binary, I only see assembly code, with that ugly “No source available” in Eclipse:
No Source Available, debugging in assembly
But wait: GDB is able to do pretty much everything you can imagine, so here is how to debug multiple binaries with GDB and Eclipse, and to turn the above into something which is easy to debug:
Debugging with Symbolics
To me, one of the most frustrating things working with ARM Cortex-M cores are the hard fault exceptions. I have lost several hours this week debugging and tracking an instance of a hard fault on an ARM Cortex-M0+ device.
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 128×128
One of the biggest road blocks (beside of closed source) using the BLE (Bluetooth Low Energy) stack from NXP is that it requires expensive tools to compile and build the stack. The good news is that I have now the NXP BLE stack for the Mikroelektronika Hexiwear ported to Eclipse and GNU gcc build tools for ARM 🙂
NXP BLE Stack in Eclipse
The Achilles Heel of the Mikroelektronika Hexiwear is its charging: the charging and USB connector are only designed for a limited number of plug-unplug cycles, and it does not have a wireless charging capability like the Apple iWatch. Until now! I have built a DIY wireless charging system for the Hexiwear 🙂 :
Wireless Qi Charging the Hexiwear
This is yet another milestone on my journey to combine the Hexiwear with the Raspberry Pi: now I can send take over control of the Hexiwear with openHAB running on the Raspberry Pi:
Controlling Hexiwear with openHAB
I’m using the NXP FRDM-K64F board in several projects: it is reasonably prices, has USB, Ethernet, micro SD card socket and connectors for Bluetooth classic and Nordic Semiconductor nRF24L01+ 2.4 GHz transceiver:
NXP FRDM-K64F Board
But one issue I have faced several times is that the board works fine while debugging and connected and powered by a host machine, but does not startup sometimes if powered by a battery or started without a debugger attached. I have found that the EzPort on the microcontroller is causing startup issues.
The Hexiwear (see “Hexiwear: Teardown of the Hackable ‘Do-Anything’ Device“) is a small and portable sensor node with built-in BLE (Bluetooth Low Energy) transceiver. In a research project we try to use multiple Hexiwear in a classroom environment and to collect sensor data on a Raspberry Pi. The Raspberry Pi 3 Model B running Linux has an on-board BLE transceiver too, so why not binding them (wirelessly) together?
Raspberry Pi 3 connected with Hexiwear over BLE
Well, things seemed easy at the beginning, and as always, there are many things to learn on a journey like this…
MCU on Eclipse 