Category: Crazyflie

Home / Blog

Crazyflie 2.0 bootloader and USB

  2014-11-04  |     |    2 Comments

The production of the first Crazyflie 2.0 batch is still on track. Currently all the components are being purchased and when they are all in, the assembly will start. We are still busy preparing things for the production, but we have now slowly shifted over to software and firmware development. The last week has been spent implementing the bootloader and implementing our communication protocol (CRTP) over USB support.

The bootloader has gone from a simple piece of firmware to something that’s more complex. For the Crazyflie 2.0 we have a dual-MCU architecture, which means that we have to flash two MCUs instead of one. Aside from that we now also support bootloading via Bluetooth LE as well as the enhanced shockburst protocol. Another fact that complicates things is that the nRF51 uses a closed binary for it’s Bluetooth LE support, which means we have to take special care when upgrading it. But the trickiest part of all this is to make it safe so that it’s always possible to rescue the system without needing a JTAG/SWD dongle if something goes wrong. It’s important to get it right, since the bootloader is flashed during production it can’t be updated at a later stage without using JTAG/SWD.

The Crazyflie 2.0 only has one button and it’s connected to the nRF51. Instead of directly switching on/off the power to the platform like on the Crazyflie 1.0, the button is now multi-functional. Pressing it will turn on/off the power and put the nRF51 to sleep, but holding it down when powering on the Crazyflie 2.0 will affect the start-up behavior. By holding it down 1.5 seconds the bootloader will launch and by holding it down 5s the STM32F4 will start in DFU mode (Device Firmware Upgrade). One of the reasons for designing in the DFU functionality was to use it as a last resort to rescue the system in case we couldn’t make the nRF51 bootloader secure. Another reason for it is that we always try to design in lots of possibilities, even if we can’t find a use for it we are hoping someone else will.

Crazyflie 2.0 boot arch

CRTP over USB is something that’s been on our TODO list for at least 2 years, but we have never gotten around to it. One idea we had was for building a bigger quadcopter using a Raspberry Pi and a Crazyflie connected to it via USB. The Crazyflie would still be used as the real-time control board, but would receive commands on the USB. This would allow the Crazyflie to become a quadcopter control board using our normal Python API for commands from Linux. This way we could for instance create a higher level autonomous system. But now we needed it for one of our test-rigs, so we had to sit down and get it done. For the implementation we use a raw USB device (i.e class 0) where we use the end-points to send CRTP packets back and forth from the PC. Since a CRTP packet is smaller than a USB packet, there’s no need for flow control or any extra protocols, we just receive new packets on the OUT requests and send a new packets back on the IN requests (if there’s any available). This fits nicely into the current architecture of the Crazyflie Python Lib and the firmware, but it still needs some cleaning up. Once everything is done it will be merged into the main firmware as well.

Crazyflie 2.0 production tests

  2014-10-28  |     |    1 Comment

We kicked off the Crazyflie 2.0 production about one week ago and we are still working hard on ensuring the best possible quality of the production. To do so we have a test specification/plan that is executed on all the produced units. Making test protocols is something we have had some experience of in our former day-jobs, but it is always a challenging and time consuming task. However the reward is great, good tests ensure good quality to the end user. The higher the production quality is, the happier everyone is, and the more time we have to do other things like developing new features :-).

The tests runs on an assembled PCB and first thing to verify is an electric test checking that voltages and current consumption are normal. Then the board gets programmed.

For the original Crazyflie, the testing was heavily based on the power on self-test. This is still the case with the Crazyflie 2.0 which allows to make sure that everything is working in factory as well as every time a Crazyflie gets powered (this power-on-self-test is the first thing to run before assembling the Crazyflie).

For Crazyflie 2.0 we also needed to create new tests for the expansion port. First of all we needed to check that the connector is mounted properly and that the pins for the expansion port are able to pass though the PCB. Secondly we also have to test the electrical connectivity. For this we have created a special expansion test board which, allows the Crazyflie to self test all expansion connections. This board is detected by the 1-wire memory which is mounted on the test board. When it is inserted it will automatically trigger the test code which checks all connections.

To do tests on a limited budget you will have to get creative. E.g. to do output power and frequency test for the radio communication on the Crazyflie and Crazyradio we are using the rfExplorer. It is a neat cheap 2.4GHz spectrum analyzer that we control from Python which can measure the radio frequency and output power. ICT or bed of nail tests are also very expensive and instead we use test fixtures with pogo-pins to test the electronics. It doesn’t get as extensive as a net checking ICT but with some clever testing using the software most components can be tested anyway. We have added some photos of the original Crazyflie test rig to this post. We will soon travel to the Seeedstudio office in Shenzhen in China and we will take photos of the new production and test equipment.

Crazyflie 2.0 expansion board template

  2014-10-20  |     |    1 Comment

First of all, thanks to everyone that helped us out during the pre-order. Today we are finishing the last details and tomorrow Seeedstudio will launch the production of the first Crazyflie 2.0 batch! It’s been a hectic couple of months here at Bitcraze and it feels great to finally have reached this point. For the first batch we will manufacture more units than were pre-ordered. So from now up until the units are ready we will continue the pre-order, but without the discounted prices. The first batch is planing to start shipping mid-December. We are prioritizing the discounted pre-order but will ship everything as soon as possible.

Last week we published the iOS prototype code for controlling the Crazyflie 2.0. This week we are publishing the Crazyflie 2.0 expansion board template project. The project is done using KiCad and includes the schematics, the footprint mapping and an initial layout with the connectors in the correct place. The license of the template project is CC-BY 4.0. In order for users to more easily see what their expansion board will look like and how it will fit, we have included the Crazyflie 2.0 board outline as well as some key components that might interfere.

We are really excited to see if any cool expansion board projects will come out of this template. So if you feel like giving it a try then head over to GitHub, clone the repository and add some cool stuff. Any ideas of what to do?

Crazyflie 2.0 exp template

Crazyflie 2.0 exp schematic

 

 

 

 

Crazyflie 2.0: The tiny modular quadcopter

  2014-10-07  |     |    15 Comments

This weekend we spent at the Maker Faire in Rome and got to meet lots of fellow geeks and makers. Even though it was busy times at the Bitcraze booth, we got a chance to walk around a bit and see other projects. It’s really inspiring to see what people come up with! It was also the first time we got the chance to show off the new Crazyflie 2.0 to the public and the feedback was really positive. We have realized that we might be a bit wide in our description of the new platform. There’s lots of new features that we are very eager to talk about, but maybe we should focus a bit more on the biggest improvements. With two weeks left on the pre-order we have been trying really hard to get some extra attention for the new platform, but haven’t really succeeded yet. This might be one of the reasons.

So even though there’s lots of new features we would really like to highlight the new expansion port. It’s been something that we have been talking about internally for a while now and we are really excited that we managed to fit it in. Like we wrote in an earlier post we used some exotic use-cases to figure out what to include in the expansion header. For example this resulted in the ability to charge the battery from the expansion board, like we are doing with the Qi wireless charging expansion board. Since the Crazyflie 2.0 has the ability to connect multiple expansion boards (both on top and bottom) we also needed some way to determine what boards are added. So one of the pins in the port is used as a 1-wire memory buss. Each expansion board has a 1-wire memory that allows identification of the board, it’s revision and what resources it uses. This way we can adapt the features available from the computer client or mobile device when the platform is connected.

Below is an overview of what’s available in the expansion port:

Crazyflie 2.0 expansion connector

For the pre-order we have managed to include 4 expansion boards: the LED-expansion, the Qi wireless charging expansion, the breakout expansion and the prototyping expansion. Aside from these boards we also have some prototypes of more expansions. Before the pre-order we were working really hard on a GPS expansion board, but in the end we didn’t think the current prototype had enough precision to launch. We reached about 10-20 meters accuracy with locking times of about 2-3 minutes and didn’t have time to spin another prototype. During the fall we will work on perfecting the design so we reach a level of performance that we feel is good enough.

We also have a prototype for a distance sensor to be used for precision landing. After looking for a solution for a while we finally found the VL6180, a time of flight sensor from ST. The range is not very long, but combined with the high precision pressure sensor mounted on the Crazyflie 2.0 we think the result can be very good. We also have an uSD expansion that we are currently testing.

After getting feedback from the visitors we met at the Maker Faire we have also decided that we will be designing an Edison adapter expansion for the Crazyflie 2.0. The Edison board is fairly small and light, so it should be possible to design an expansion board that has the 70-pin expansion connector featured on the Edison. Our plan is to use some of the interfaces in our expansion board to connect to the Edison, like I2C, UART and SPI.

Last but not least we are also working on an analog FPV expansion board. It’s still just an early prototype, but we think it’s something that a lot of users might be interested in.

As we will continue making more and more boards we also hope the community will take the opportunity to do so as well. We will soon release templates for KiCad making it really quick to get started. What board would you like to make? Let us know what you think about the new expansion port. Do you have any ideas for boards or any comments about our planned ones? We would love to get some feedback!

We would also like to say congratulations to Mihir Garimella on being one of the winners of the Google Science Faire 2014 with his project the Flybot! He used the Crazyflie to work on escape maneuvers similar to those of fruit flies. Really great work!

 

The Crazyflie 2.0 pre-order has started!

  2014-09-26  |     |    8 Comments

We are really happy to announce that we are starting the pre-order for the Crazyflie 2.0 today! After spending nearly 10 months doing development, we have reached a point where we are very happy with the design and the performance. Now all we have to do is to kick off the production and that’s where the pre-order comes in.

During the next three weeks we will be taking pre-orders for the Crazyflie 2.0 and related products. After the three weeks has passed we will start the production and the current estimate for shipping the products is the second week of December. As a reward to users that want to help us out by pre-ordering our products, we are lowering the prices with about 15% until the 16th of October when the pre-order ends.

So, just to clarify:

  • Pre-order end: 16th of October
  • Estimated shipping: Second week of December

If you want to know more about the Crazyflie 2.0 and what it’s about, then have a look at the Crazyflie 2.0 product page. It explains a bit about the communication (Bluetooth LE and Crazyradio), the expansion boards and gives you an idea what you could use the platform for. The Crazyflie 2.0 developed with developers in mind, so it features thins like wireless firmware upgrade, real-time parameter setting/getting and data logging using graphs. To make it easier for developers to get going we provide a pre-installed virtual machine that contains most of our tool-chains for building firmware and software, as well as KiCad for the hardware design.

For the Crazyflie 2.0 pre-order we aren’t just making the Crazyflie 2.0 available, we are launching a full set of products to support it. Here’s the list of the main products and the expansion boards that are included in the pre-order:

  • Crazyflie 2.0: The next generation of our flying open development platform with lots of new features
  • Crazyradio PA: The same mechanical footprint and price as the current Crazyradio, but now with a power amplifier that we have tested to above 1km range (line-of-sight) with the Crazyflie 2.0
  • Debug adapter kit: An easy way to debug the nRF51 and STM32F4 on the Crazyflie 2.0 by using an adapter board for connecting a standard 20-pin/100mil JTAG or 10-pin/50mil Cortex-debug cable
  • LED-ring expansion board: Fly into the night in style with this expansion board featuring 12 bright RGB LEDs that can be individually controlled and two strong white front-facing LEDs
  • Qi expansion board: Charge your Crazyflie 2.0 without any wires with this inductive charging expansion board using Qi
  • Breakout expansion board: Easy solderless prototyping with a board designed to fit a breadboard to try out your designs on the ground
  • Prototype expansion board: With space for prototyping and access to all the pins in the Crazyflie 2.0 expansion port there’s lots of possibilities with this board

We are also including all the spare parts in the pre-order to make sure that everyone gets a chance to get what they need together with their Crazyflie 2.0. Here’s the list of parts:

For the release we wanted to make a video explaining a bit the new platform, but since we have been really short on time we’re not done yet. Instead we are publishing a short video showing the Crazyflie 2.0 in action together with the LED-ring expansion board. The video also features the traffic light hack we did a few weeks ago.

Have a look at the Getting Started page for the Crazyflie 2.0 for assembly instructions or the wiki documentation for the project to see how to assemble the new solderless Crazyflie. There’s also some Expansion port documentation available as well as User Guide. We are still working on filling out more of the documentation, so bare with us. With the hardware completed we are now refocusing on the firmware and software. We have built in lots of neat features into the new Crazyflie 2.0 hardware that we now need to add software support for. So over the coming months we will be working on the iOS/Android apps and the Crazyflie PC client as well as the firmware. We will of course keep everyone updated of the progress here on our blog. Once the Crazyflie 2.0 products start shipping we will publish all the code and hardware design on our GitHub.

Starting with the pre-order of the Crazyflie 2.0 we are also lowering the price for the current version of the Crazyflie. The Crazyflie Nano Quadcopter 10-kit is lowered from $149 to $116 and the bundle with the Crazyradio is lowered from $179 to $146. So if you can’t wait until December then have a look at the current version over at Seeedstudio.

Crazyflie 2.0 pre-order teaser

  2014-09-22  |     |    9 Comments

Finally it’s getting really close and we are very excited to say that the pre-order of the Crazyflie 2.0 will start this week! We will post more details about it during the week, until then here’s a short teaser from our release video :-)

 

Hard at work preparing for the pre-order

  2014-09-15  |     |    3 Comments

The last couple of weeks we have been spent on finishing the testing of the hardware and preparing lots of practical things for the production of the new Crazyflie 2.0. With almost all the hardware finished, we are now working hard on preparing for the pre-order. The number of products that are included in the Crazyflie 2.0 launch is a lot more than we had for the current Crazyflie, which means that there’s a lot more things to be done. We are really excited about releasing Crazyflie 2.0 and can’t wait to see what you will do with it. We don’t want to promise anything but stay tuned, the pre-order launch has never been so close :-).

Crazyflie 2.0: Radio range test

  2014-09-08  |     |    10 Comments

As you might already know we have added a 20dBm RF amplifier to the Crazyflie 2.0 as well as to the Crazyradio PA. We have had high hopes of getting a more stable link and much better range with this. We have done a lot of tests in the building we are sitting in and already experienced a big improvement in range. However radio range is a tricky thing as it depends on so many things and when we have tested it outside of the office we could only get a stable link for about 80m. This is very different from the documents we read where we could expect up to a kilometer of range! Maybe the fifteen wifi networks that where present outside our office played an effect.

So this weekend I set out to do some test on the country side. I packed my bag and mounted the Crazyradio PA on a 1m stick which I put in my bag so it could reach higher than my head. Then I took the bike to get to the country side. I got a lot of strange looks while bicycling. It was first when I reached the country side, it came to me that bicycling around with an antenna sticking out your backpack might be interpreted the wrong way :-o. After a while I reached a good spot and decided to put the Crazyflie still somewhere and instead take the computer with me so I could see what was happening. As the nRF51822 can take RSSI measurements we made a simple python program where the computer pings the Crazyflie and the Crazyflie responds with the RSSI measurement. We save the data in a CVS file which can be plotted in real time. I hang the Crazyflie in a bush, started the Crazyflie 2.0 at channel 10 and 250k air data rate, fired up the plot and took the bicycle and started pedaling.

After 100m I still had a solid connection, very good sign. After 500m the RSSI had dropped to about -80dBm but still a stable connection. After 1300m it got really shaky, about -100dBm, as the line of sight was obstructed by some trees and the road turned as well, 1.3km, LOS, that’s a huge improvement from the 80m we got back at the office. We know these circumstances are very optimal but at least it shows us we are not way off and hopefully we can expect half of that range in a more real situation. We have still not tuned the matching network for the antenna, which we will do soon, so hopefully we can expect yet another improvement. I also did a test with a hacked Crazyflie 2.0 with a duck antenna. With this one I got about -70dBm at the same 1.3km spot. This could be a great hack for special applications that require long radio distance as it could probably go beyond 2km range LOS, both up- and downlink.

Crazyflie 2.0: LED-ring expansion

  2014-09-01  |     |    6 Comments

A while ago we did a hack where we attached a NeoPixel ring to a Crazyflie. It was just a quick hack to show the concept, but we really liked the results. So we added some more firmware to easily be able to create new effects for the ring and also made it controllable using the Leap Motion. When we started talking about what expansion boards to do for the Crazyflie 2.0, we instantly thought about this hack. It’s fun to play around with the patterns, but it’s also great for lighting up the ground below that Crazyflie. To be able to light up in front of the Crazyflie we also added two strong white LEDs facing forward. Imagine a Sci-Fi movie where an abandoned alien ship is found. To explore it they first send in a small autonomous flying vehicle for exploration that lights up the walls and floor while blinking with some patterns, that’s the look we were going for :-)

To accomplish this we have designed an expansion board with a ring of 12 W2812B RGB modules as well as two strong front facing LEDs (the kind that’s used for LCD backlight). The board is 3cm in diameter and weighs about 3,5g. To make sure the LEDs are lit correctly as the battery voltage changes (especially when it get’s low) we added a DC/DC step-up/down to the board.

Like always, we are looking forward to seeing what fun things our users will do with this board :-)

Crazyflie 2.0: Qi inductive charging expansion

  2014-08-25  |     |    5 Comments

One of the boards that we have been working on is an inductive charging expansion for the Crazyflie 2.0. Some of you might remember way back when we did an inductive charging hack for the Crazyflie. It’s always been very compelling with wireless charging, we’re not sure why. Maybe it’s because it feels a bit magic :-) For our inductive charging expansion board we choose the Qi standard, which is used in many cellphones today and finding a cheap charger for it is pretty easy. The board is designed around the BQ51013B Qi chip from Texas Instruments. Our initial testing of the board shows that it’s operating at about 65% efficiency and manages to provide an output of around 1A at 5V. The board weights about 5g, but we might be able to improve that  a bit, and is 30x30mm. Now all we need is a dock that we can automatically land on :-)

Here are some images of our current prototype, the final version will look a bit sleeker. The jumper sticking out on the side is for current measurements. It won’t be mounted in the final version, but the pads will still be there. So if you would like to measure the current you can cut the track and solder a jumper for it.