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• 3D printed body

  davedarko • 04/16/2016 at 14:20 • 3 comments

  Hey all, @davedarko writing. As you might have seen at the #Hackaday | Belgrade event - I've brought my Tote with 3d printed legs along to the workshop. There I was asked for the files and @Radomir Dopieralski told me I could share them in a log. It took me a while to chamfer some edges and fix the hip orientation of my design, but now I finally have all the parts in a presentable state. You can find the STL files for printing in the file section. The design files are made with 123D Design by Autodesk. That's the 3rd time I completely disassembled my Tote.

  

  Read more »

• Compiling Your Own Firmware

  Radomir Dopieralski • 04/13/2016 at 22:16 • 0 comments

  For anyone who wants to build their own version of firmware, here's a really quick howto:

  • Clone the Tote-HAD repository from https://bitbucket.org/thesheep/tote-had

    hg clone https://bitbucket.org/thesheep/tote-had

  • Clone the Micropython repository from https://github.com/micropython/micropython/

    git clone https://github.com/micropython/micropython.git

  • Follow the README.md for the ESP8266 port to setup the build environment. You can also follow one of the guides at http://forum.micropython.org/viewforum.php?f=16
  • Before compiling, copy or link the files from the python directory of Tote-HAD to esp8266/scripts
  • Compile and flash normally, as the README says.

  You can also skip the main.py file (it's the file that gets executed on the board start), and instead create it after flashing -- this way you will be able to modify it without recompiling the firmware:

  with open("main.py", "w") as f:
      f.write("import server; server.main()")

  There are some tools that make it easier to upload files to the ESP8266, like here: https://github.com/wendlers/mpfshell

• Fixed Firmware

  Radomir Dopieralski • 04/11/2016 at 20:50 • 28 comments

  As promised, I fixed the firmware for the robot -- now it will start walking immediately after being switched on, and after connecting you can control it. Below are flashing instructions.

  1. Download the firmware-combined.bin file, and save in the current directory.
  2. Download the esptool.py file, and save in the current directory.
  3. Connect the USB2TTL to the pins on the side of the robot:
     • gnd ↔ gnd
     • rx ↔ tx
     • tx ↔ rx
  4. Connect together two pin holes (or pins, if you soldered pins in there) on the other side of the robot (leave the third pin alone):
     • gnd ↔ sda
  5. Connect the USB2TTL to your computer.
  6. Switch on the robot.
  7. Run the flashing command:

     $ python esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=8m 0 firmware-combined.bin

  On Windows/Mac change the path to the USB2TTL port accordingly.

  8. Wait for the firmware to flash. If you get an error, try again.
  9. Switch the robot off.
  10. Remove the connector from the pin holes.
  11. Switch the robot on and see it walk. Congratulations, you have the new firmware.

  Note, that flashing new firmware will not delete the network information from the board, if you had the robot connect to some network. If you want to do that, you can with this command (before flashing the firmware):

  $ python esptool.py --port /dev/ttyUSB0 erase_flash

• Command Line

  Radomir Dopieralski • 04/10/2016 at 20:05 • 0 comments

  The robots are built, but due to a bug in the communication code, they didn't walk "straight out of the box". The bug makes them wait for a connection before they start walking, and I will be fixing this soon, and I will provide new firmware to flash soon.

  In the mean time, you can play with your robots by using a serial connection. In fact, you will have access to the Python console on them. All you need is a 3.3V USB2TTL converter (I gave out a couple at the workshop, it's that red thing with USB plug on it). If you don't have one, I highly recommend you get it anyways, because they are extremely useful in debugging all sorts of projects anyways, and you will also need to to flash the new firmware, both for the Arduino and the ESP8266 parts of the robot.

  Connecting

  To connect the serial interface of the ESP8266 on your robot to your computer, you will need to use the three pins on the left side of the robots. If you look at the bottom side of the board, you will see they are labeled, from front to back, "gnd", "tx" and "rx". Use three female-female dupont cables, and connect the "gnd" pin on the robot with the "gnd" pin on the USB2TTL, the "rx" pin of the robot with the "tx" pin on the USB2TTL, and the "tx" pin on the robot with the "rx" pin on the USB2TTL.

  • gnd ↔ gnd
  • rx ↔ tx
  • tx ↔ rx

  Next, plug the USB2TTL into your computer (or even better, a USB hub connected to your computer), and open a serial terminal with speed 115200 on the serial port that appears. On Linux, I use the screen program for that, with the command:

  $ screen /dev/ttyUSB0 115200

  On Windows you can use PuTTY for that (you might need to have the drivers for the USB2TTL installed first). I have no idea how to do that on macs, but there must be some way. Once you do that, you should see black screen... Then switch on the robot, and you should see something like this:

  rll��|�l�|�l�b|����r�b�b��nn�lnn���bplblrlp�n��lbn�|쌌��b��nn�l��l`�nnl`nr���nr�`p�n�r�����bn�|lb��nn�l`�nnl`nr���nrrl`p�n�r�����쌜bn�|쌎b��nn�l`�nnl`nr���nl`r��nl`�l��|��rrnb��l��b�lb쌜���l��b�lrldon't use rtc mem data
  ll��|��rrnb��ll�p�b�b쌜���l��b��lrl�l��|��rrnb��ll�|�b�b쌜����b�lblrl��rl���bl�br|�bll���lb��n�nn��l�|�l�l��l������l`�n��

  That's the booting messages of the ESP8266 received at a wrong baud rate. Don't worry about that. Now, if you press Ctrl+C, the program that is executing on the robot will be interrupted, and you will see this:

  MicroPython v1.6-374-g2c407bc-dirty on 2016-04-07; ESP module with ESP8266
  Type "help()" for more information.
  >>>

  That's the Python console prompt, also known as the REPL console. You can type Python code in there, and it will get executed on the robot.

  Walking

  So how do you make it walk? Type in this code:

  from robot import Robot
  from gait import Creep
  robot = Robot()
  gait = Creep(robot)
  for frame in gait.run():
      pass
  

  That should get the robot creeping forward. To change the directions you can set the dx, dy and rotation attributes on the gait object, and repeat... Read more »

• Quick Notes

  Radomir Dopieralski • 04/09/2016 at 18:12 • 10 comments

  The workshop just finished, and I will have more to say about it, but for now I need to take a couple of notes for improving things, in case I will be doing it again.

  • Cheap screwdrivers are useless,
  • The screws that come with servos are really bad for this, make sure to use the 1.5x3M screws,
  • Check the software also in the AP mode, not just when it's connected to your home WiFi,
  • Investigate the glue-less approach to making feet,
  • Provide more detailed instructions. Separate instructions for left and right legs, better instructions for what to plug where, mark the colors for B&W prints,
  • Tell people to use the servo horns that came in the bag with the servo, as they differ very much for servos from different sources.
  • Order plastic bags and divide the parts into kits. Make sure to use servos from the same source in each kit,
  • Add instructions for cutting off the servo "ears" for the hip servos,
  • More detailed instructions for centering the servos,
  • Tell the organizers about the upper limit on the number of people in advance. Order everything at once, in bulk,
  • The cheap LiPo chargers are 1A, not good for batteries smaller than 1000mAh,
  • Have enough USB2TTLs for everyone to use,
  • Double-check all the boards for soldering errors and missing parts,
  • Bringing a soldering iron and basic tools was a great idea,
  • Send the kits to the organizers as a package, to avoid customs problems at the airport,
  • Tell people to bring laptops,
  • Add web interface,
  • Have it blink LEDs in different patterns to indicate different stages and/or errors,
  • Print the address of the project website on the instructions and the PCB,
  • Have a helper for every 10 people,
  • 4h is barely enough to assemble everything, forget about programming them,
  • If servos are erratic, check the battery,
  • People who came are amazing! Thanks!

• Software

  Radomir Dopieralski • 04/07/2016 at 15:22 • 0 comments

  I finished the Arduino code and flashed to all the boards, and now I'm in the process of flashing the Python code onto all the ESP-01 modules, and setting their SSIDs.

  As usual, the software doesn't do all that I wanted it to do. By default it makes the robot walk forward and listen for connections. I wrote a small PyGame program that lets you control the robot from your computer with the keyboard. That's it.

  Things I wanted but didn't have time to do:

  • there is only the "creep" gait, no "trot" gait,
  • the communication with the Arduino controller is one-way, no telemetry,
  • thus, no battery voltage monitoring,
  • there is no remote Python console, for that you have to connect the serial cable.

  However, all that can come in the future versions of the software. During the workshop I will show you how to modify and flash the software for both of the microcontrollers, so hopefully you will be able to perform the updates when new versions become available here.

  Oh, the code repository is at: https://bitbucket.org/thesheep/tote-had/src

• First Steps

  Radomir Dopieralski • 04/04/2016 at 20:52 • 0 comments

  With the kits all soldered and ready, I'm focusing on the software development. As usual, I won't have everything I wanted there at first, so expect software updates after the workshop. However, the basic walking is a must, so I'm focusing on that. The Micropython for ESP8266 is actually usable enough now, and I only needed a small patch to slow down the I²C communication, so that the Arduino can keep up without clock stretching. After doing that, and adding the Python code to the scripts directory, I compiled a working version of the firmware. Here are the first steps of the robot:

  Of course for now the walking is slowed down (with long pauses between movements) and the leg reach is small -- it should be much faster and smoother when I tune it. I will also need to add a way to control it over WiFi, and to read any sensors connected to the Arduino. By default, there is going to be only one telemetry value you can read, the battery voltage, but of course you can connect pretty much any sensor you can think of.

  Also note that the front left hip servo is broken and only moves into two positions -- that's because I had to use recycled servos for the prototype. On the workshop we will use the new servos that just arrived, and they should all be fine.

• Mass Production

  Radomir Dopieralski • 04/02/2016 at 17:05 • 0 comments

  This was a productively spent day.

  

• 1 Done, 24 More To Go

  Radomir Dopieralski • 04/01/2016 at 11:43 • 0 comments

  The remaining parts just arrived, including the package of 200 servos:

  

  I'm still waiting for 20 batteries, but hopefully they will arrive sometime next week.

  I finally can start assembling the PCBs for the kits. I already did the first one:

  

  You can see some unpopulated headers and footprints there -- that's because they are optional, and the parts I got are not enough to fill them on all 25 boards. But that also means that you can improve your robot even further once you take it home. I will be posting detailed instructions here about each optional feature, so that hopefully this will be easy. We can also talk about this on the workshop, if there is time.

• Clock Stretching Woes

  Radomir Dopieralski • 03/30/2016 at 19:39 • 2 comments

  The parts are still trickling in, but I'm waiting for the rest of the PCBs to start the mass-production of the workshop kits. Hopefully they will arrive tomorrow or Friday, so I can do it over the weekend.

  Less good news is that the tracking number for the 200 servos that I ordered a week ago is not working (the seller gave me 4 different ones so far, none working). It's too late to order this from a different seller, and there is no brick-and-mortar shop that I know that has those. So it's possible that I will have only 10 complete kits, and 15 kits without legs. I'm still hoping that the servos will arrive on time, but there is nothing I can do with this. Frustrating.

  Finally, on the software side, I made some progress debugging the I²C issues (after two evenings of analyzing the scope). I even found and tried a completely new slave library by Pololu, but decided to switch back to Wire.h for now (I might use that library later, especially since it has a workaround for the I²C bug in Raspberry Pi). Anyways, the issue seems to be that the Arduino slave is sometimes too slow for the 100kHz I²C, and the ESP8266 implementation doesn't support clock stretching, so it can't slow down when needed. The good part is that I found a way to compile a version of the firmware with slower I²C, so this shouldn't be a problem.

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