Shop OBEX P1 Docs P2 Docs Learn Events
I don't know what propeller board to use on my rocket project. (Also some rocket code couldn't hurt) — Parallax Forums

I don't know what propeller board to use on my rocket project. (Also some rocket code couldn't hurt)

Elnino2002Elnino2002 Posts: 5
edited 2019-09-11 03:34 in General Discussion
I'm currently at the sourcing stage to build a rocket with a data logger and I'm thinking of using the Basic Stamp with a BMP280 (Barometer), and a MPU-6050 (accelerometer/gyro). Does anyone have any recommendations? Also if anyone has done something similar before I would like to hear about it! Also if anyone is willing to share any information that could be used in my coding that would be appreciated as well. Thanks!

Comments

  • whickerwhicker Posts: 749
    How large is the rocket (height of payload area and diameter)?

    It looks like these sensors have an I2C bus.
    Yes Basic Stamp 2's will be able to communicate with I2C

    What is the sample rate you would like to acquire the sensor data at? (for example number of samples per second).
    Also where do you want the data to be stored?
    This will help determine what controller you would need.
  • Cluso99Cluso99 Posts: 18,069
    IIRC someone has rocket code for a propeller. Perhaps you could change your title to include rocket code.
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2019-09-07 09:08
    You don't have to be a rocket scientist to know that rockets don't have Propellers :lol:

    But I have used Propeller chips as commercial data loggers on very many occasions in many products. An 8-bit memory constrained Basic Stamp just doesn't compare to an 8-core 32-bit Propeller chip, not just in processing power, but also in ease of use.
  • iseriesiseries Posts: 1,496
    There are several boards available for this type of measurements.

    Sparkfun has 9DOF SENSOR STICK.
    Adafruit has BNO055 breakout board.

    There is also a sensor fusion board that combines these sensors with a high speed processor to read all these values and return EULER angles. EM7180 + LSM6DSM + LIS2MDL or EM7180 + MPU9250 + BMP280.

    Mike
  • Dave HeinDave Hein Posts: 6,347
    I suggest using a Propeller instead of a stamp. In the future you will probably want to add more features to your data logger, and the stamp may have problems doing this since it must do everything in a sequential manner. The Propeller has 8 cogs, which will allow you to perform multiple tasks in parallel.
  • Elnino2002Elnino2002 Posts: 5
    Thanks for all of the replies, my current rocket is decently small with a payload size of about 1.58" in width and about 6" in height (Aka the size of a bt-60 tube). With every launch there is improvement in size and tech. The sample rate of which I would like to record at is as fast as practical and I plan on storing my data in a micro sd card. All of you seem to agree on using a board with a propeller chip, what boards would you recommend? The propeller mini has caught my attention, and also the propeller quickstart for maybe a later generation. Also to give a little more information on my plans, the goal is to take a rocket with one of these boards as the flight computer to a higher altitude of around 50,000+. Thanks for all your help!
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Take a look at the Propeller FLiP module. It will fit your size constraints and is very reasonably priced.

    -Phil
  • Peter JakackiPeter Jakacki Posts: 10,193
    Phil Pilgrim (PhiPi) wrote: »
    Take a look at the Propeller FLiP module. It will fit your size constraints and is very reasonably priced.

    -Phil

    It seems to be targeted towards the education market rather than embedded because it emphasizes on-board USB serial which you hardly ever use, and certainly not in flight, but does nothing about data storage such as Flash or microSD.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2019-09-11 04:00
    Peter Jakacki wrote:
    It seems to be targeted towards the education market rather than embedded because it emphasizes on-board USB serial which you hardly ever use, and certainly not in flight, but does nothing about data storage such as Flash or microSD.
    Au contraire, mon ami! Onboard USB serial is very important for programming the unit, even if it's not used for anything else. I have an OEM app that uses the extra 32K EEPROM for data storage. It's plenty. I've also used it in a stage lighting app, programmed over a wireless connection, since the module is inaccessible without a very tall ladder. The compact size was vital for this application. Onboard switching voltage regulation is very efficient, which makes it ideal for battery-powered apps. Parallax has really pulled out the stops with this module, and the price is right -- for much more than just educational applications.

    -Phil
  • Mike GreenMike Green Posts: 23,101
    It depends on how much data you're dealing with. The FLiP has a 64KB EEPROM of which only 32K is used by the ROM bootstrap loader to store the program to be run on reset. The 2nd 32KB is available for logging or other data storage. If that's enough, then the FLiP module has enough for your application. You can add more flash in 64KB (24LC512) increments up to 1MB total using the same I/O pins as the existing on-module EEPROM.
    The on-board USB serial interface is used to load the program to be run on reset and can be used for debugging.
  • Peter JakackiPeter Jakacki Posts: 10,193
    I have serial USB cables that I plug in just like the old Prop Plug did etc. The FLiP still needs "a cable" anyway.
    Having USB on the actual Prop board is more of a hindrance since it precludes other forms of serial coms and also takes up board space that could be used for microSD or high density Flash (not the EEPROM).
    Having an extra row of 4 pins allows for +5V and I2C so that this same connector can have a serial Bluetooth module plugged in when it is not sitting on the test bench but is now not as accessible inside a case mounted on some contraption.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2019-09-11 05:58
    Peter Jakacki wrote:
    Having USB on the actual Prop board is more of a hindrance since it precludes other forms of serial coms ...
    Huh? There are 28 other undedicated pins that can be used for serial comms. In my OEM app, I use two of them for serial I/O to one sensor, and another for 1-wire comms to another. Another 12 get used to drive an 8-digit, 7-segment LED display. Even when not being programmed, the device I designed receives its power through the microUSB connector; so, yes, that interface is very handy to have on board. The board that the FLiP plugs into is quite small, with many of its active components mounted between the FLiP's DIP connector pins. I don't know why Parallax would waste board space with a microSD connector, since most apps would not make use of it.

    Anyway, I would be hard pressed to find a module more adept at meeting the needs of OEMs, so I'm just not sure where your criticism is coming from. Maybe you just haven't tried it?

    -Phil
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2019-09-11 06:09
    Phil Pilgrim (PhiPi) wrote: »
    Peter Jakacki wrote:
    Having USB on the actual Prop board is more of a hindrance since it precludes other forms of serial coms ...
    Huh? There are 28 other undedicated pins that can be used for serial comms. In my OEM app, I use two of them for serial I/O to one sensor, and another for 1-wire comms to another. Another 12 get used to drive an 8-digit, 7-segment LED display. Even when not being programmed, the device I designed receives its power through the microUSB connector; so, yes, that interface is very handy to have on board. The board that the FLiP plugs into is quite small, with many of its active components mounted between the FLiP's DIP connector pins. I don't know why Parallax would waste board space with a microSD connector, since most apps would not make use of it.

    Anyway, I would be hard pressed to find a module more adept at meeting the needs of OEMs, so I'm just not sure where your criticism is coming from. Maybe you just haven't tried it?

    -Phil

    You are taking this too personally (maybe I might react the same in the same situation though). I merely said that I consider it targeted more towards education rather than OEM products, of which I have many more than I can recall using the P1. The FLiP looks nice and the inclusion of a real switcher rather than those linear regs is a welcome inclusion and certainly the USB "is" handy on the bench.
    Any boards that I've designed with integrated USB normally need it for normal operation yet I still use series resistors in there so that I can override the USB port if I need. Otherwise in the bulk of my designs I have no need for USB other than programming. On the other hand, practically all my designs use SD or microSD for all kinds of logging purposes although I see that many times some other Prop designs seem to "run out of memory" and cannot utilize FAT32 software anyway, but the P1 has plenty of capability I find.
    Viva the P1!
  • Cluso99Cluso99 Posts: 18,069
    I build a tiny board with microSD called P8XBlade. See my signature for a link.
  • iseriesiseries Posts: 1,496
    Yes, one the problems facing this launch is a battery that will fit the tube and not take up all of the tube.

    You may want to just use a flight controller as everything is built in including a flight recorder.

    Check this unit out as it is small and has all the sensors built in and ready to go just add power....

    PixRacer Auto Pilot

    It is only 35mm square.

    Mike
  • JRoarkJRoark Posts: 1,215
    I’ve run a FLIP on series-soldered button cells. You’re not looking at a lot of run time, but for a up-and-down rocket flight they should be plenty if weight is a huge issue. If not, just stick a 9-volt in there.
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2019-09-12 01:59
    I like the FLIP too and use it for tasks around the shop and for development where the USB power is convenient. However, the FLIP's baseline current is about 10mA, which is what it draws from the USB port (or 5-9V supply), even when it is operating at RCslow. Yes, part of that is lighting up the green LED. Like JRoark noted, that might acceptable for a short rocket flight.

    Consider too that an SD card recording at the highest rate is going to consume something like 30mA or more. That would drop to less than 1mA if it is not active, deselected. The average depends on your required sample rate. The sensors will probably be an insignificant power drain. Recording to EEPROM or flash memory might take less current, but to use those you'd have to think more carefully about the sample rate versus the total length of the flight. Say 32kBytes with 8 bytes per sample, gives 4096 samples, say at one per 0.5 second gives a total deployment time of ~34 minutes. The point is to minimize weight and size of the instrument package and its battery.
  • Mike GreenMike Green Posts: 23,101
    edited 2019-09-12 03:12
    There is an I/O driver in the Propeller Object Exchange written in Spin for flash EEPROMs (here). It lets you have named files and more than one can be open at a time. It does not provide for updating a file "in place" since flash cannot be rewritten ... only copied with the original area erased afterwards. Fancy file systems like those on an SD card take care of this automatically.
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2019-09-12 22:38
    I'd be a concerned about vibration and maybe heat too with an SD card in a socket. The same goes for most kinds of connectors in the system. You want everything to be very secure.

    @Elnino2002, There were protracted discussions and learning experiences in the old "Stamps in Class" forum, where a group of middle school students launched a rocket at Black Rock Desert.
    https://forums.parallax.com/discussion/113538/ideas-on-off-switch-to-activate-a-datalogger/p1
    https://forums.parallax.com/discussion/122688/arliss-team-nh/p1
    http://forums.parallax.com/discussion/100967/combining-temp-humidity-sensor-program-with-a-simple-movement-program/p1
    They used a BASIC Stamp of course, which is still quite a capable and fun microcontroller. You might find some ideas there, if you wade through it!

  • LedgerLedger Posts: 1
    How big is your rocket?
  • JohnCJohnC Posts: 64
    edited 2019-10-16 19:56
    Check out page 37 here. I wonder if you can still send away for the pre-programmed EEPROM? PCB artwork is included, of course.

    https://www.americanradiohistory.com/Archive-Radio-Electronics/90s/1990/Radio-Electronics-1990-10.pdf

  • Elnino2002Elnino2002 Posts: 5
    I'm glad to hear about the Propeller FLiP Board, I think it will work perfectly for what I'm trying to do. At this point I'm upgrading to a 94mm ID rocket tube so space will not be as much of an issue anymore. Since I've seen so many different recommendations, I'd like to make it clear that this will not be the only board on board of my rocket, I plan on including off the shelf boards as a fail safe while testing my own code. The reason I've upgraded is because I'm going to be building a series of rockets for my certification attempts and I'm designing this current one for cert 1 and also possibly cert 2. Additionally I'm going to be running an Xbee (With a decently long antenna) to confirm status and/or location of my rocket. More updates to follow. Thanks for the help!
  • Capt. QuirkCapt. Quirk Posts: 872
    How are you planning to insure the accuracy of the data?

    G force measurements on the way up seems safe, but how
    do you plan to measure atmospheric pressure & temperature
    accurately? Depending on how your cargo compartment is
    vented during the assent, the internal air pressure may be
    either greater or less than the the outside pressure, and it will
    skew the data.

    If the air pressure is less during assent, your altitude data will
    be higher than it actually is, and lower if it pressurizes.

    Air temp affects density altitude also.

    On the other hand you could monitor the altitude data on the
    descent, but that might rely on good interpretation of the
    accellerometer data.

    Another good project would be a hand held weather station
    like what the Drag Racers use. I think you will find that your
    rocket data will change depending on that days weather.


    Bill M.


  • Elnino2002Elnino2002 Posts: 5
    You make a good point on how hard it might be to get accurate data, I'll be sure to look into that once I get to the software side of things. Right now I am still working on getting the structural side of things together and I'll certainly think about that when I get to the cargo stage of the build. Thanks for the advice.
  • Dave HeinDave Hein Posts: 6,347
    Google "model rocket static ports", and you'll find many links on the subject. Just a small hole in the side of the rocket is enough to ensure that the pressure inside of the rocket is the same as on the outside.
  • Capt. QuirkCapt. Quirk Posts: 872
    edited 2019-11-27 02:51
    Dave Hein wrote: »
    Google "model rocket static ports", and you'll find many links on the subject. Just a small hole in the side of the rocket is enough to ensure that the pressure inside of the rocket is the same as on the outside.

    The "model rocket static ports" are what I was talking about, and there is plenty
    of info to be found with a quick search. The problems with pressure or vacuum
    are real, and careful design your vents should be an important design feature.


    Bill M.

    I found examples of rockets pressurizing and separating before apogee because
    of the pressure build up. Other examples of the Bernoulli (venturi effect) causing
    a vacuum.
Sign In or Register to comment.