Announced a new Raspberry:
Today, I’m pleased to be able to announce the immediate availability of Raspberry Pi Zero, made in Wales and priced at just $5. Zero is a full-fledged member of the Raspberry Pi family, featuring:
- A Broadcom BCM2835 application processor
- 1GHz ARM11 core (40% faster than Raspberry Pi 1)
- 512MB of LPDDR2 SDRAM
- A micro-SD card slot
- A mini-HDMI socket for 1080p60 video output
- Micro-USB sockets for data and power
- An unpopulated 40-pin GPIO header
- Identical pinout to Model A+/B+/2B
- An unpopulated composite video header
- Our smallest ever form factor, at 65mm x 30mm x 5mm
With this, shields like the PXF 2.0, NavIO, Raspilot and the one from VirtualRobotix may have a way to cut down costs.
Comments
Would Xenomia Linux meet the real-time requirements for PWM, or is the timing for the RaspPi and/or Linux just too innacurate in general?
Old, but relevant, attempt with BeagleBoard xM: http://veter-project.blogspot.com/2012/04/precise-pwms-with-gpio-us...
@Laser Developer - that is perhaps a good novel idea, but a built-in IMU is just about $10 so you might want one onboard independent of any other peripherals. It all depends on the use-case, it seems ready to use packaged Flight Controllers in a small size like the PixHawk, APM, the racing controllers (CC3D, naze), etc. are in good demand. Another point is that I believe some of the newer ARM SoCs do already have builting CAN transceivers so if you want CAN it may be better to use those instead of the Raspberry Pi.
@Patrick - when using DMA on the Broadcom chip I wouldn't expect it to be inaccurate, jittery, etc., as long as the system clock is stable. I haven't done timing tests but since there's no operating system involvement I'd expect it to be just as good as the BBB's PRU. It's true that last I looked Ardupilot HAL didn't have DMA-based PWM generation, it did have DMA-based PWM reading, and it did have support for the single or dual on-chip hardware PWM on the broadcom chip which may be why NAVIO uses the other chip.
PWM generation from the Broadcom might not be very accurate nor predictable under linux. If it was, the NAVIO or the PIXHAWK2 would not require the PCA9685 chip. For the BBBMini this chip is not required because the BBB has PWM generated by the PRU within the CPU.
@Victor, you have released products on both platform, I would really appreciate your comment on the PWM imlementation using native GPIO -vs- dedicated chip like the PCA9685
@Andrew - Isn't your hat pointing in the wrong direction? Why not provide a dual redundant UAVCAN port instead? Sensors and peripheral hardware are becoming smarter so it's not necessary to have any active sensors attached to the processing platform. Turning the processor into a "component" provides for much better future-proofing, especially given the current rate of development of processing power. Similarly, sensors are getting more intelligent and a multi-master bus like CAN makes lots of sense.
For example, one laser altimeter in development includes built-in barometric sensing as a backup to the laser and uses UAVCAN for communication to allow for multiple redundancy. Similarly, combined IMU/GPS are becoming the new standard. Just saying :).
I think most would be totally happy with a hat that brings in an I2C MPU6050 + magnetometer + barometer, 5V protection for a few inputs for the receiver signal and a few outputs stepped up to 5V for the PWMs broken out in servo connector layout, possibly an analog input chip. All in all it should be possible to do it all in under $15, currently that's what it costs you to produce a DIY-style raspberry Pi based Arducopter board without using a pre-built hat/cape/shield and doing it as a proper manufacturing process should only be cheaper.
Note that there's no need for real IO extenders for the receiver signal or the PWM generation, the broadcom chip's DMA can already generate or capture those signals just fine.
@Chris thats true.
It would need to be a simpler and smaller approach for a Rpi Zero APM thingie than a 6 Layer All-in-one board.
But what functionality should be dropped to shrink it down and at the same time make it a somewhat feature complete Rpi Zero APM Hat ?
I get the feeling that the diversity of users/usage makes it harder to get everyone happy.
Still we have more powerful processors in phones that use less space. Cost more though.
Patrick Awesome idea!!
I though of using the ESP8266 for telemetry but not for substituting other components! Do you know if it can handle low bandwidth FPV video. Probably not... still a good option for telemetry and maybe some still images though.
I'd like to see a sub $100 platform for "disposable drones" for swarming one way trips.
looks like the future for APM code has a bearing towards Linux. now with the pi zero and BBBmini shield something amazing is about to happen. something within the footprint of APM. I am not a Linux guy but am quite excited by this development. I am ready to order my Pi zero and BBBmini just for the fun of it.
@Linus, I think the PXF2.0 is a 6 layer board? They are not cheap to get manufactured, they are typically 4 times the cost of a 4 layer board - at least the places I've looked at (for a qty of 5 or 10). That is why I've been playing with the BBBMini. I personally think there is room for another board...... But it may not be technically feasible.
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