raspberry pi model 2 (quad-core)

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Paul,
I just ran across your below message about looking for a brave rPi enthusiast to test your build of ArduinoIDE/Teensyduino. I came here looking for a way to have an rPi or BBB dynamically load different sketches into a USB connected Teensy3.1. I guess there are two discrete parts to this... there is doing the development work and compiling on the BBB/rPi and then there is just loading pre-compiled code. Let me know if you still could use a tester because I have a BBB, rPiB, rPiB+ and rPi2 ready to go for testing. I also have T3.0, T3.1, T3LC. Thanks and talk soon!
-frenchy (Steve French)
www.voltvision.com


PaulStoffregen said:
I do have an experimental and so far, pretty much untested build of the toolchain and of the Arduino IDE with Teensyduino's patches. It's just waiting for some brave Raspberry Pi enthusiast to test....

But until after Teensy-LC is released, I won't be able to respond to any bug reports or even offer much guidance about how to use it.
Click to expand...
 
I have replaced my RPi B with the RPi 2. The '2 is much faster. It's on my LAN, using a share on my NAS for primary data storage.

I've bought some ARM boards for professional development work (SWD required) from this company. High quality, good interactions. Lots of plugin boards for adding-on peripherals.
http://www.waveshare.com/
http://www.waveshare.com/product/modules.htm
http://www.waveshare.com/catalogsearch/result/?q=stm32

Probably not a good choice for hobby/student work as compared to the T3/LC.
 
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@Stevech: FWIW, I just bought a 5" hdmi monitor for my raspberry pi from waveshare (well the vendor I bought it from was spotpear, but waveshare actually made it). After going through the upgrade process, I no longer need the 'special' disk from waveshare as the drivers are now open-sourced. Granted, there were problems in doing the upgrade, in that I had to dig in to the find the pin used for interrupts (25) to add to the device tree. However, that appears true in all of Pi-land as the new kernel for Pi 2 and device tree modifications for Pi Hats roll through and make previous special patches obsolete (Adafruit monitors have had the same problem).
 
Does the linux sched_setaffinity/cpusets/isolcpus stuff work well enough that a RPi2 with one core dedicated to a single real-time task would consistently have faster response time than a teensy 3.1? Or are there little gotchas (like some kernel interrupts) remaining?
 
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It would be nice to have a low cost HDMI on the RPi. So far, I seldom use the HDMI port - as I run VNC to access the PI from a PC or laptop, or my Android tablet.
But the 4" looks appealing.
 
jonr said:
Does the linux sched_setaffinity/cpusets/isolcpus stuff work well enough that a RPi2 with one core dedicated to a single real-time task would consistently have faster response time than a teensy 3.1? Or are there little gotchas remaining?
Click to expand...

The Teensy will likely always have lower ISR latency. And Linux does tend to block interrupts for long periods of time. Indeed the RPI 2's muiti-core CPU is much faster. So, "it depends!"
 
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I would have to imagine that you still might need to resort to kernel level driver with PWM/DMA like the raspberry pi neopixel driver to get timing sensitive stuff done correctly. Granted the Pi runs at a much faster clock rate than the Teensy, and that can make up for a lot. However, you are likely to get better answers over at the Raspberry Pi forums, rather than here: https://www.raspberrypi.org/forums/.
 
stevech said:
It would be nice to have a low cost HDMI on the RPi. So far, I seldom use the HDMI port - as I run VNC to access the PI from a PC or laptop, or my Android tablet.
But the 4" looks appealing.
Click to expand...

It depends on what you want to use the monitor for. I have the 2.8" PiTFT from Adafruit (320x240, resistive touch), and it is nice for my 'Cambridge' camera (Raspberry Pi + PiTFT screen + camera) inside of a Polaroid 95A body, where I'm only running the camera software (the version I'm running from Adafruit is hardcoded for the PiTFT display).

However, it is rather small for text type work. So, I bought the 5" HDMI waveshare monitor (800x480, resistive touch). As I mentioned, Pi-land is undergoing a disruptive change right now, and I had to figure out how to get the touch drivers to work with the new device tree. I figure in a few months, all of the examples will be updated, and people won't have to dig as much. However, in using the 5" monitor, it is better than the PiTFT, but I do have to have the monitor fairly close to see it. More things will work at 800x480 than 320x240, but the wireless configuration menu in in X wants a larger screen and doesn't have a scroll bar. For the Cambridge camera, the 5" screen is about the biggest that will fit in the Polaroid 95A. The 5" monitor uses HDMI for the display and the SPI pins + gpio 24/25 for the touch screen, and it sits on top of the Pi with a special hdmi cable like the PiTFT displays.

I've been thinking of making a tablet for use when I'm traveling and the laptop is just too big. I originally looked at 7" screens for the Pi, but I decided to go instead with a Dragon Touch 8" tablet (1280x800 IPS), which is self contained. I don't have to build a case to contain all of the wires from the normal DIY 7" lcd. I also don't have to deal with 12v power (when you jump from 5" to 7", the monitors tend to want 12v power, since the assumption is the main use is for car backup monitors and child video monitors, and you have convenient 12v power).

That being said, the 7" HDMI waveshare monitor is nice in that it uses USB for the touch screen, but it is 'only' 800x480, so it gives me a bigger screen, but no more resolution than the 5" monitor I have. As far as I can tell, the 7" monitor uses USB power and not 12v. They must have just released the 7" display. I don't recall it the last time I was looking for displays (or the ebay resellers I was looking at don't yet carry it).

Note, the Waveshare 4" LCD does not use HDMI, it uses SPI to drive the screen, so if you are doing something video related, you won't get a high frame rate. The 2 5" displays that waveshare makes (the one that I have that is made to sit on top of the Pi, and plugs into the first 26 pins, and the other one that uses USB for touch screen) do use HDMI.

Of course since the 4" LCD uses SPI, I imagine with some amount of hacking, you could get the Teensy to support it.
 
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The low end Android tablets are so cheap! Like $50 or less for a 7 or 8 in. one. Maybe 10" in the minimum. On personal trips, I use my Acer Android tablet and my wife's iPad (I like the Android one's human interface much better - it's consistent among apps whereas Apple never did that). My HTC smartphone on Verizon LTE... can be an accesspoint for the tablets - no extra cost from Verizon. Great within a hotel room or in the car.

But, we diverge here off topic.
 
VoltVisionFrenchy said:
Paul,
I just ran across your below message about looking for a brave rPi enthusiast to test your build of ArduinoIDE/Teensyduino. I came here looking for a way to have an rPi or BBB dynamically load different sketches into a USB connected Teensy3.1. I guess there are two discrete parts to this... there is doing the development work and compiling on the BBB/rPi and then there is just loading pre-compiled code. Let me know if you still could use a tester because I have a BBB, rPiB, rPiB+ and rPi2 ready to go for testing.
Click to expand...

I haven't touched the Raspberry Pi stuff recently. That experiment was on Arduino 1.0.6 and Teensyduino 1.21. Since then, Arduino released 5 new versions in the 1.6.x line, and I've released 2 new versions of Teensyduino, and the Raspberry Pi foundation released the quad core board. So the completely untested stuff is now pretty old. :(

At this point, your best bet would still be to develop all the Teensy code on a regular computer and create pre-made HEX files. Then use the Raspberry Pi version of Teensy Loader. Both the GUI and the command line version are ported to RPi. The GUI version also includes the "teensy_reboot" program, which searches for a Teensy and tries to ask it to reboot.
 
I was looking at running a RTOS on one of the processors to handle I2C, SPI and some general I/O but, I don't think the interrupt controller can assign HW interrupts across processors.
 
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