In “Tutorial: FreeRTOS 10.0.1 with NXP S32 Design Studio 2018.R1” I showed how to use a custom FreeRTOS with the S32 Design Studio (ARM). The OSIF (OS Interface) provides an operating system and services abstraction for the application which is used by other S32K SDK components:
OSIF in S32K for ARM Eclipse Project
“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).
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?
I recently discovered a nice feature in Eclipse CDT: the ability to show the return value of a function:
Return Value shown as Variable
By default, the GNU compiler (gcc) optimizes each compilation unit (source file) separately. This is effective, but misses the opportunity to optimize across compilation units. Here is where the Link Time Optimization (LTO, option -flto) can help out: with a global view it can optimize one step further.
The other positive side effect is that the linker can flag possible issues like the one below which are not visible to the compiler alone:
type of '__SP_INIT' does not match original declaration [enabled by default]
Warning by LTO
Decisions, decisions! Such long weekends like Pentecost are a real challenge for a family with engineers:
Well, my family vote was kind of clear: they have chosen that second option. Not to mention that hidden technology piece in it, but that was part of the deal ;-).
And I’m sorry: this article is not about BBQ (for this see “Smoking BBQ Baby Back Ribs – Swiss Style“), it is about technology: I’m using the NXP MCUXpresso IDE and tools for many of my projects (see “Eclipse MCUXpresso IDE 10.1 with integrated MCUXpresso Configuration Tools“). Right before the this extended weekend, NXP has released the new v10.2.0 version, so here is where that technology exploration piece comes into play. Checking the release notes, this version number change includes so many cool stuff I decided to have a look and to check it out. Of course always having an electronic eye on the baby back ribs!
MCUXpresso IDE v10.2.0
The map file produced by the GNU linker includes lots of information, however it is very cryptic to read. In “Listing Code and Data Size for each Source File with GNU and Eclipse” I showed how the GNU size utility can be used to report the code and data size for each object file. The Eclipse based MCUXpresso IDE comes with another nice view which shows detailed information about code and data allocation:
Symbol Viewer in MCUXpresso IDE
It’s April Fool’s Day, but be assured this is not a joke ;-): I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge. This release includes several smaller bug fixes and components have been upgraded for FreeRTOS V10.0.1.
SourceForge
In “Flash-Resident USB-HID Bootloader with the NXP Kinetis K22 Microcontroller” I presented how I’m using the tinyK22 (or FRDM-K22F) with a flash resident USB HID bootloader. To make sure that the loaded application is not corrupted somehow, it is important to verify it with a Cyclic redundancy Checksum (CRC). The NXP KBOOT Bootloader can verify such a CRC, but how to generate one and how to use it is not really obvious (at least to me), so this article explains how to generate that CRC.
CRC Values for KBOOT
