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:
i.MX RT1021
FreeRTOS includes a nice feature to give me information about how much time every task is spending running on the system:
FreeRTOS Runtime Information
This tutorial explains that FreeRTOS Runtime Statistics feature and how it can be turned on and used.
NXP has just released the 10.2.1 update of their flagship Eclipse based IDE. While the number increase from 10.2.0 to 10.2.1 indicates a minor release, there are a several things which make me move over to that new release.
MCUXpresso IDE 10.2.1 build 795
My usual workflow is: edit – build – debug and repeat. And this for the same project again and again. So here are a few tips how to make these iterations faster with Eclipse. One thing is to use the F11 shortcut to debug the last launched/debugged application:
Debug Last Launched
“There is no ‘S’ for Security in IoT” has indeed some truth. With all the connected devices around us, security of code should be a concern for every developer. “Preventing Reverse Engineering: Enabling Flash Security” shows how to prevent external read-out of critical code from device. What some microcontroller have built in is yet another feature: ‘Execute-Only-Sections‘ or ‘Execute-Only-Memory‘. What it means is that only instruction fetches are allowed in this area. No read access at all. Similar like ‘read-only’ ‘execute-only’ it means that code can be executed there, but no other access from that memory is allowed.
Locked Code
In this article I describe the challenges for a toolchain like the GNU gcc, and how to compile and link code for such an execute-only memory.
In many cases it is very useful to see the generated assembly code produced by the compiler. One obvious way to see the assembly code is to use the Disassembly view in Eclipse:
Disassembly View
But this requires a debug session. An easier way is to use command line options to generate the listing file(s).
In the C programming language it is good practice to pass values by reference (using a pointer), especially for large set of data. For example the following function takes a message string and pointer to integer data which then is printed to the console:
static void printData(const char *msg, const int *intBuf, size_t bufSize) {
puts(msg); /* print message */
for(int i=0; i<bufSize;i++) {
printf("buf[%i] = %i\n", i, intBuf[i]);
}
}
NXP not only sells general purpose microcontroller, but as well a portfolio of automotive devices which includes the S32K which is ARM Cortex based. For this device family, they offer the S32 Design Studio (or S32DS) with its own Eclipse distribution and SDK. The interesting part is that the S32DS includes Processor Expert (which is a bit different from the ‘mainstream’ Processor Expert). It comes with its own components for the S32K SDK which includes a component for FreeRTOS. But that component in S32DS 2018.R1 comes with an old V8.2.1 FreeRTOS component:
FreeRTOS 8.2.1 in S32DS 2018.R1
So what to do if I want to use the latest FreeRTOS (currently 10.0.1) with all the bells and whistles?
By default, the FreeRTOS threads do not show up with the SEGGER J-Link debug connection in the Eclipse based NXP S32 Design Studio IDE. But don’t worry: Here is how to get it working with SEGGER J-Link debug connection:
FreeRTOS Threads in Eclipse Debug View
The ARM DWT (Data Watchpoint and Trace) is an optional feature of the ARM-Cortex-M, and many Cortex-M3, M4 and M7 devices have it implemented. With it comes a cycle counter which counts the cycles spent. In Cycle Counting on ARM Cortex-M with DWT I described an approach how the application on the target can access the cycle counter.
The MCUXpresso IDE shows that cycle counter in the Eclipse Registers view:
Cycle Counter in Register View
MCU on Eclipse 