The spring university semester is coming to an end, and the Infotronic course closed with a Sumo robot challenge. Great challenge, new technologies, innovative approaches and funny designs 🙂
ToF (Time-of-Flight, see “Tutorial: STMicroelectronics VL6180X Time-of-Flight LIDAR Sensor“) sensors are fun: they measure the time the light takes to travel to an object and back again. That way they can measure the distance to object with a millimeter accuracy. An ideal sensor for a battle robot: 🙂
I believe in ‘life-long-learning’. With this I continue to learn and discover new things every day. I’m writing tutorials to give something back to the community from which I have learned so much.
On top of this, I receive emails on a nearly daily basis, asking for help. Many articles have the origin in such requests or questions. I prefer questions or comments in a public forum, because that way I feel all others can benefit from it. Last week Alessandro contacted me with this:
I hope this find you well! I’m starting to using ARM processors, but I find them quite complicated on the configuration side. I started in the past with PIC micro (PIC16) with asm, and I found them quite straightforward to be configured (clock, IO, peripherals, …). Then I moved myself on C language, and on PIC18 without any big issues.
Now I would really like join the ARM community, I see that these processors are what I’ve always looking for, on energy, calc power, peripherals, and FINALLY on IDE (editor, toolchain and utilities)… AMAZING!!!”
The topic is about how to start learning developing for ARM. Alessandro agreed to make this public, so I thought this might be a good topic for an article?
For many of my applications I need to measure a distance. I have used ultrasonic sensors, but there view angle (beam) is not able to detect smaller objects, it very much depends on the object surface and angle, it is slow and not very precise. I have used infrared sensors, but here again it depends on the infrared reflection of the object in range, it depends the amount of reflected light is not really telling much about the distance, and yet IR reflection is subject of material and object targeted.
But there is yet another sensor type to consider: ToF! ToF (or Time-of-Flight) sensors have a built-in LIDAR: The sensor is sending out light pulses and measures how much time it takes for the light to come back. Similar to ultrasonic sensors (see “Tutorial: Ultrasonic Ranging with the Freedom Board“), but instead of ultrasonic it uses an infrared laser light. Or think about a radar system using an infrared laser light.
From time to time I face some problems which are really hard to find. Mostly these kind of bugs are very timing sensitive and depend on interrupt execution order. Maybe a dangling pointer is overwriting memory, code is running wild, or some functions are not reentrant as they should be. For these kind of bugs, good tools are worth their weight in gold. The Percepio FreeRTOS+Trace and the Segger SystemView have helped me many times to narrow down such kind problems in my applications. Another ultimate tools is hardware trace: Now I have a Segger J-Trace Pro for ARM Cortex-M in my arsenal of bug extinguishing weapons on my desk:
Dear bugs, look what I have on my desk. Your hiding time is over! 🙂
The STMicroelectronics STM32F103 (ARM Cortex-M3) Nucleo boards include the on-board ST-Link v2 circuit which allows to debug the board. This circuit is similar to the OpenSDA circuit found on Freescale boards. Unlike the Freescale OpenSDA, the ST-Link is only the ST-Link: it is not possible to load a P&E Multilink or Segger J-Link or firmware on it. Luckily, the ST-Link has a SWD connector, but this connector is a non-standard one. So how can I debug that board with an Eclipse based environment with GNU ARM Eclipse plugins and a Segger J-Link?