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Re: Skatebot Platform -- More

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  • drew_alley
    Hello, The San Diego store in Place D Orleans has quite a big supply of the skateboard toys on hand, also. Andrew ... traction
    Message 1 of 15 , Jul 2, 2002
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      Hello,

      The San Diego store in Place D'Orleans has quite a big supply of the
      skateboard toys on hand, also.

      Andrew

      --- In ORE_bits@y..., "drew_alley" <drew_alley@y...> wrote:
      > Hi gang,
      >
      > The "Totally Extreme Skateboard" toy is available at San Diego in
      > Merivale Mall for $15.
      >
      > It's a four-wheeled, differential drive, r/c toy that can easily be
      > hacked for use as an inexpensive mobile platform, as described by
      > these articles:
      > http://www.seattlerobotics.org/encoder/200008/stakebot.html
      > http://www.seattlerobotics.org/encoder/200010/SkatebotWon.html
      >
      > I picked one up and it's pretty fun, it'll almost be a shame to take
      > it apart ;) It's a fast and maneuverable platform w/ decent
      traction
      > on carpet. O-rings or some other type of rubber/foam tires could be
      > added for traction on smooth surfaces.
      >
      > It's a tad big for a mini-sumo, measuring in at ~12 cm x ~11.5 cm,
      > but has potential for a great line-following platform.
      >
      > Cheers,
      > Andrew
    • Aaron
      I ve been playing with mine, and I m pretty impressed. It s not designed for fine motor control, but everything else is pretty good. The motors draw around 50
      Message 2 of 15 , Jul 2, 2002
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        I've been playing with mine, and I'm pretty impressed. It's not designed for fine motor control, but everything else is pretty good. The motors draw around 50 to 60mA unloaded and around 140mA stalled when running at 6V. That is about 10 times better than I was expecting. The motors look like cheapies, but they aren't too bad.

        It has a pretty noisy drivetrain, and likely won't last forever. On the other hand, I have a spare, so I don't care. <grin>

        When the skateboader is unbolted from the top of the chassis, the base sits about an inch and a half tall. The circuitry in the thing is just a simple RF decoder and H-bridge. I debated for a while and then decided not to use the builtin h-bridge. I want to try locked anti-phase PWM control, so I'm better off with an h-bridge chip instead I figure. The RF receiver section is interesting though.

        I'm turning my robot into a line follower/maze solver which is meant to be interactive with some kids. I tore apart the handheld transmitter and hooked it up to my parallel port. I'm going to use the four 'commands' (left motor forward, left motor reverse, right motor forward, right motor reverse) to communicate with the robot from a PC. The RF receiver chip on the bot has 4 (well, actually 6, but only 4 are used on this thing) digital outputs which are either high or low. I've fed that into my pic processor and I'll let it make some decisions based on the inputs. Basically I'm going to have a VB program on the PC which has a couple of buttons which makes to robot do certain things. I figure that'll hold the kids attention for maybe 2 minutes. <grin>

        So, I'm pretty happy with this thing. I liked the fact that the base was pretty cool, but I'm really starting to appreciate the RF section too. For $15, you really can't go wrong.

        If anyone buys this to get started with robotics, but doesn't know where to go from there (ie- don't know how to get started with the microprocessor and whatnot), let me know. Once you have that base, it only takes about $20 in electronic parts to get started with a fairly smart robot. If there is any interest, I can put on a small demo at the next meeting on how to build a small microprocessor board and get started....

        Aaron


        On Tue, 02 Jul 2002 13:36:02 -0000 "drew_alley" <drew_alley@...> wrote:

        > Hello,
        >
        > The San Diego store in Place D'Orleans has quite a big supply of the
        > skateboard toys on hand, also.
        >
        > Andrew
        >
        > --- In ORE_bits@y..., "drew_alley" <drew_alley@y...> wrote:
        > > Hi gang,
        > >
        > > The "Totally Extreme Skateboard" toy is available at San Diego in
        > > Merivale Mall for $15.
        > >
        > > It's a four-wheeled, differential drive, r/c toy that can easily be
        > > hacked for use as an inexpensive mobile platform, as described by
        > > these articles:
        > > http://www.seattlerobotics.org/encoder/200008/stakebot.html
        > > http://www.seattlerobotics.org/encoder/200010/SkatebotWon.html
        > >
        > > I picked one up and it's pretty fun, it'll almost be a shame to take
        > > it apart ;) It's a fast and maneuverable platform w/ decent
        > traction
        > > on carpet. O-rings or some other type of rubber/foam tires could be
        > > added for traction on smooth surfaces.
        > >
        > > It's a tad big for a mini-sumo, measuring in at ~12 cm x ~11.5 cm,
        > > but has potential for a great line-following platform.
        > >
        > > Cheers,
        > > Andrew
      • drew_alley
        Aaron, I agree that the platform isn t built for precision or longevity, but the price point is right on. Plus, there s all the fun and additional
        Message 3 of 15 , Jul 2, 2002
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          Aaron,

          I agree that the platform isn't built for precision or longevity, but
          the price point is right on. Plus, there's all the fun and
          additional applications that can be had w/ the r/c portion, as you
          mention below.

          As for getting started, I'd be interested in some PIC info, especially
          in the way of getting a programmer up and running, since my current
          experience is limited to the 6811.

          Cheers,
          Andrew

          --- In ORE_bits@y..., Aaron <aaron@b...> wrote:
          > I've been playing with mine, and I'm pretty impressed. It's not
          designed for fine motor control, but everything else is pretty good.
          The motors draw around 50 to 60mA unloaded and around 140mA stalled
          when running at 6V. That is about 10 times better than I was
          expecting. The motors look like cheapies, but they aren't too bad.
          >
          > It has a pretty noisy drivetrain, and likely won't last forever. On
          the other hand, I have a spare, so I don't care. <grin>
          >
          > When the skateboader is unbolted from the top of the chassis, the
          base sits about an inch and a half tall. The circuitry in the thing is
          just a simple RF decoder and H-bridge. I debated for a while and then
          decided not to use the builtin h-bridge. I want to try locked
          anti-phase PWM control, so I'm better off with an h-bridge chip
          instead I figure. The RF receiver section is interesting though.
          >
          > I'm turning my robot into a line follower/maze solver which is meant
          to be interactive with some kids. I tore apart the handheld
          transmitter and hooked it up to my parallel port. I'm going to use the
          four 'commands' (left motor forward, left motor reverse, right motor
          forward, right motor reverse) to communicate with the robot from a PC.
          The RF receiver chip on the bot has 4 (well, actually 6, but only 4
          are used on this thing) digital outputs which are either high or low.
          I've fed that into my pic processor and I'll let it make some
          decisions based on the inputs. Basically I'm going to have a VB
          program on the PC which has a couple of buttons which makes to robot
          do certain things. I figure that'll hold the kids attention for maybe
          2 minutes. <grin>
          >
          > So, I'm pretty happy with this thing. I liked the fact that the base
          was pretty cool, but I'm really starting to appreciate the RF section
          too. For $15, you really can't go wrong.
          >
          > If anyone buys this to get started with robotics, but doesn't know
          where to go from there (ie- don't know how to get started with the
          microprocessor and whatnot), let me know. Once you have that base, it
          only takes about $20 in electronic parts to get started with a fairly
          smart robot. If there is any interest, I can put on a small demo at
          the next meeting on how to build a small microprocessor board and get
          started....
          >
          > Aaron
          >
          >
          > On Tue, 02 Jul 2002 13:36:02 -0000 "drew_alley" <drew_alley@y...>
          wrote:
          >
          > > Hello,
          > >
          > > The San Diego store in Place D'Orleans has quite a big supply of
          the
          > > skateboard toys on hand, also.
          > >
          > > Andrew
          > >
          > > --- In ORE_bits@y..., "drew_alley" <drew_alley@y...> wrote:
          > > > Hi gang,
          > > >
          > > > The "Totally Extreme Skateboard" toy is available at San Diego
          in
          > > > Merivale Mall for $15.
          > > >
          > > > It's a four-wheeled, differential drive, r/c toy that can easily
          be
          > > > hacked for use as an inexpensive mobile platform, as described
          by
          > > > these articles:
          > > > http://www.seattlerobotics.org/encoder/200008/stakebot.html
          > > > http://www.seattlerobotics.org/encoder/200010/SkatebotWon.html
          > > >
          > > > I picked one up and it's pretty fun, it'll almost be a shame to
          take
          > > > it apart ;) It's a fast and maneuverable platform w/ decent
          > > traction
          > > > on carpet. O-rings or some other type of rubber/foam tires
          could be
          > > > added for traction on smooth surfaces.
          > > >
          > > > It's a tad big for a mini-sumo, measuring in at ~12 cm x ~11.5
          cm,
          > > > but has potential for a great line-following platform.
          > > >
          > > > Cheers,
          > > > Andrew
        • Aaron
          ... Well, the first step to putting together a microcontroller platform is to get all the goodies. Now, I m the kind of guy that likes free stuff, so here is
          Message 4 of 15 , Jul 5, 2002
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            On Tue, 02 Jul 2002 17:01:08 -0000 "drew_alley" <drew_alley@...> wrote:

            > As for getting started, I'd be interested in some PIC info, especially
            > in the way of getting a programmer up and running, since my current
            > experience is limited to the 6811.

            Well, the first step to putting together a microcontroller platform is to get all the goodies. Now, I'm the kind of guy that likes free stuff, so here is how I go about it...

            Go to ti.com (http://www.ti.com) and order some free samples of the following items:
            L293DNE, L293NE, SN754410NE - h-bridges which are good for 600mA/1A (small motors)
            PCF8574AN - i2c port expander
            Throw in some BQ40xx's and TIBPAL22VP10-20CNT's just for the hell of it... you'll find a use for them later (I like the 1M and 2M BQ varieties myself). The BQs are battery backed sram modules and the TIB is a programmable logic array (PAL).

            Go to analog.com (http://www.analog.com) and order some free samples of the following item:
            ADXL202 - This is an accelerometer, which is useful for playing with in the future.

            Go to national.com (http://www.national.com) and order some free samples of the following items:
            LMD18200 - large motor H-bridge (3 amps + current sense)
            LM1084IT-5.0 - low dropout 5A 5V voltage regulator

            Go to Maxim (http://www.maxim-ic.com) and order some free samples of the following items:
            MAX233A, MAX233, MAX232A, MAX232 - rs232 tranceivers
            MAX7301 - port expander
            DS89C420 - cool 8051 microcontroller
            DS2251T - sweet 8051 microcontroller modules - I've never actually been able to get a sample of these though

            There are lots of other goodies at all the websites also, so poke around. Sometimes TI has the rs232 chips available for sampling also.

            Finally, get a 16F877 or 16F876 microcontroller. I haven't managed to wrangle and samples from the local rep yet, but every 6 months or so I give it another try. You'll probably have to break down and get this from either Future Active in town here, or from Digikey. You'll also need to get a crystal or oscillator for the PIC too.... get a 20M oscillator with a 20M PIC chip if you can.

            So, what you really need to get started is: PIC16F877/20, 20M oscillator, L293/SN754410/LMD18200, RS232 chip.

            That gives you the basics for just controlling a motor and having bumper switches on the robot. Other sensors are a whole other matter. There are so many choices... IR, ultrasonic, etc... I'll get into those in another email. The best bet is to get a SHARP IR module with the analog output (can't remember the name of it... GP2Dxx). It's about $11 at future active, so it is pretty decently priced. The other thing that you need (for a sumo robot or line follower anyhow) is something like the QRB1114. Digikey has them, and maybe Future does. It's a matched pair of IR transmitters/receivers in a small case.

            I'll talk more about this at the meeting on monday.

            Aaron
          • Albert den Haan
            ... OK. Now I have to ask, what do I need to do to actually get the parties named to
            Message 5 of 15 , Jul 5, 2002
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              Aaron wrote:
              >
              > Well, the first step to putting together a microcontroller platform is to
              > get all the goodies. Now, I'm the kind of guy that likes free stuff, so
              > here is how I go about it...

              < major snippage on all the lovely stuff you can get for free...>

              OK. Now I have to ask, what do I need to do to actually get the parties
              named to acutally send me the goodies? I don't work for a hardware
              firm, I'm not an accredited electronics technologist (or even employed
              in electronics), and my employer will not accept non-work related
              packages.

              Has anyone in my situation ever had success with these sample programs?

              > I'll talk more about this at the meeting on monday.
              >
              > Aaron
              >

              --
              Albert den Haan, Software Developer @ Corel Corporation
              albertd@... (613) 728-0826 x5318
            • Aaron
              ... Well, when I get stuff from these guys I don t generally have it shipped to my workplace. They ship it to Ramsey Consulting at my home address. Other
              Message 6 of 15 , Jul 5, 2002
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                On Fri, 05 Jul 2002 10:55:15 -0400 Albert den Haan <albert.denhaan@...> wrote:
                > OK. Now I have to ask, what do I need to do to actually get the parties
                > named to acutally send me the goodies? I don't work for a hardware
                > firm, I'm not an accredited electronics technologist (or even employed
                > in electronics), and my employer will not accept non-work related
                > packages.

                Well, when I get stuff from these guys I don't generally have it shipped to my workplace. They ship it to 'Ramsey Consulting' at my home address. Other times they ship to 'Matsuoka Solutions', under my wife's name.... depending on how many samples I need. I've never had any troubles. TI will eventually cut you off after a certain amount of free samples per year, but the other guys only limit you to a certain amount of samples per week.

                The only time that I use my work address is when I'm trying to get samples that can't be ordered on the web, such as the PIC processors. I've successfully gotten FPGAs and CPLDs through work.

                As an aside, when I design boards at work, I always spec. the vendors who have supported my hobbies through samples. The parts on the work boards and my hobby boards might not always be the same, but I always do try to support those guys who are generous (National, Maxim, etc...)

                Aaron
              • Aaron
                Oh ya, forgot to mention that I use personal email addresses when I m ordering stuff too... something like consulting@ottawarobotics.org or
                Message 7 of 15 , Jul 5, 2002
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                  Oh ya, forgot to mention that I use personal email addresses when I'm ordering stuff too... something like consulting@... or design@... or whatever. I don't know if it really makes a difference or not, but what the hell.

                  On that note, if anyone needs an ottawarobotics.org email address, we can arrange that.

                  Aaron


                  On Fri, 5 Jul 2002 16:28:12 -0400 Aaron <aaron@...> wrote:

                  > On Fri, 05 Jul 2002 10:55:15 -0400 Albert den Haan <albert.denhaan@...> wrote:
                  > > OK. Now I have to ask, what do I need to do to actually get the parties
                  > > named to acutally send me the goodies? I don't work for a hardware
                  > > firm, I'm not an accredited electronics technologist (or even employed
                  > > in electronics), and my employer will not accept non-work related
                  > > packages.
                  >
                  > Well, when I get stuff from these guys I don't generally have it shipped to my workplace. They ship it to 'Ramsey Consulting' at my home address. Other times they ship to 'Matsuoka Solutions', under my wife's name.... depending on how many samples I need. I've never had any troubles. TI will eventually cut you off after a certain amount of free samples per year, but the other guys only limit you to a certain amount of samples per week.
                  >
                  > The only time that I use my work address is when I'm trying to get samples that can't be ordered on the web, such as the PIC processors. I've successfully gotten FPGAs and CPLDs through work.
                  >
                  > As an aside, when I design boards at work, I always spec. the vendors who have supported my hobbies through samples. The parts on the work boards and my hobby boards might not always be the same, but I always do try to support those guys who are generous (National, Maxim, etc...)
                • stephane641
                  Yep. I used to order samples via Alcatel but this morning I created a company name (RobotiX) and I just got a confirmation email from TI! Those battery backed
                  Message 8 of 15 , Jul 5, 2002
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                    Yep.

                    I used to order samples via Alcatel but this morning I created a
                    company name (RobotiX) and I just got a confirmation email from TI!

                    Those battery backed SRAM look way cool!

                    THanks for the nice list Aaron.

                    Now that I'm on a budget I'll take FULL advantage of their samples.

                    Later,
                  • drew_alley
                    Aaron, Thanks for the sample info! I ve received a confirmation email from TI as well, but haven t heard back from National, yet. Andrew ... especially ...
                    Message 9 of 15 , Jul 8, 2002
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                      Aaron,

                      Thanks for the sample info!

                      I've received a confirmation email from TI as well, but haven't heard
                      back from National, yet.

                      Andrew

                      --- In ORE_bits@y..., Aaron <aaron@b...> wrote:
                      > On Tue, 02 Jul 2002 17:01:08 -0000 "drew_alley" <drew_alley@y...>
                      wrote:
                      >
                      > > As for getting started, I'd be interested in some PIC info,
                      especially
                      > > in the way of getting a programmer up and running, since my
                      current
                      > > experience is limited to the 6811.
                      >
                      > Well, the first step to putting together a microcontroller platform
                      is to get all the goodies. Now, I'm the kind of guy that likes free
                      stuff, so here is how I go about it...
                      >
                      > Go to ti.com (http://www.ti.com) and order some free samples of the
                      following items:
                      > L293DNE, L293NE, SN754410NE - h-bridges which are good for 600mA/1A
                      (small motors)
                      > PCF8574AN - i2c port expander
                      > Throw in some BQ40xx's and TIBPAL22VP10-20CNT's just for the hell
                      of it... you'll find a use for them later (I like the 1M and 2M BQ
                      varieties myself). The BQs are battery backed sram modules and the TIB
                      is a programmable logic array (PAL).
                      >
                      > Go to analog.com (http://www.analog.com) and order some free samples
                      of the following item:
                      > ADXL202 - This is an accelerometer, which is useful for playing with
                      in the future.
                      >
                      > Go to national.com (http://www.national.com) and order some free
                      samples of the following items:
                      > LMD18200 - large motor H-bridge (3 amps + current sense)
                      > LM1084IT-5.0 - low dropout 5A 5V voltage regulator
                      >
                      > Go to Maxim (http://www.maxim-ic.com) and order some free samples of
                      the following items:
                      > MAX233A, MAX233, MAX232A, MAX232 - rs232 tranceivers
                      > MAX7301 - port expander
                      > DS89C420 - cool 8051 microcontroller
                      > DS2251T - sweet 8051 microcontroller modules - I've never actually
                      been able to get a sample of these though
                      >
                      > There are lots of other goodies at all the websites also, so poke
                      around. Sometimes TI has the rs232 chips available for sampling also.
                      >
                      > Finally, get a 16F877 or 16F876 microcontroller. I haven't managed
                      to wrangle and samples from the local rep yet, but every 6 months or
                      so I give it another try. You'll probably have to break down and get
                      this from either Future Active in town here, or from Digikey. You'll
                      also need to get a crystal or oscillator for the PIC too.... get a 20M
                      oscillator with a 20M PIC chip if you can.
                      >
                      > So, what you really need to get started is: PIC16F877/20, 20M
                      oscillator, L293/SN754410/LMD18200, RS232 chip.
                      >
                      > That gives you the basics for just controlling a motor and having
                      bumper switches on the robot. Other sensors are a whole other matter.
                      There are so many choices... IR, ultrasonic, etc... I'll get into
                      those in another email. The best bet is to get a SHARP IR module with
                      the analog output (can't remember the name of it... GP2Dxx). It's
                      about $11 at future active, so it is pretty decently priced. The other
                      thing that you need (for a sumo robot or line follower anyhow) is
                      something like the QRB1114. Digikey has them, and maybe Future does.
                      It's a matched pair of IR transmitters/receivers in a small case.
                      >
                      > I'll talk more about this at the meeting on monday.
                      >
                      > Aaron
                    • Aaron
                      The voltage ergulator that I am using is the lm2825 from National. It s a 1A DC to DC converter which will take anything up to 40 volts and convert it down to
                      Message 10 of 15 , Jul 8, 2002
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                        The voltage ergulator that I am using is the lm2825 from National. It's a 1A DC to DC converter which will take anything up to 40 volts and convert it down to 5 volts. It's in a massive 24 pin package, but it's absolutely brilliant. It's basically a 7805 in a big package, but doesn't waste power. I totally dig it for dropping 9V down to 5 for my robots.

                        Another option is the DCR02 from TI. It's in a much smaller package, but can only do 2W. At 5 volts, that's 400mA.... which isn't too bad.

                        Another place to check for samples is ONSemi (http://www.onsemi.com). They have tons of stuff, but nothing that's I've found incredibly useful yet. ;-) The power FETs are cool though, if you are thinking about making a massive H-Bridge. They also have lots of logic chips for sample, so you could stock up I suppose.

                        Aaron

                        On Mon, 08 Jul 2002 13:54:59 -0000 "drew_alley" <drew_alley@...> wrote:

                        > Aaron,
                        >
                        > Thanks for the sample info!
                        >
                        > I've received a confirmation email from TI as well, but haven't heard
                        > back from National, yet.
                        >
                        > Andrew
                        >
                        > --- In ORE_bits@y..., Aaron <aaron@b...> wrote:
                        > > So, what you really need to get started is: PIC16F877/20, 20M
                        > oscillator, L293/SN754410/LMD18200, RS232 chip.
                      • Jon Hylands
                        ... For doing 9 volt batteries, you may want to check out the LM2940 from National. It comes in a TO-220 package (same as 7805), can handle 1 amp, and can
                        Message 11 of 15 , Jul 8, 2002
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                          On Mon, 8 Jul 2002 22:53:18 -0400, Aaron <aaron@...> wrote:

                          > The voltage ergulator that I am using is the lm2825 from National. It's a 1A DC to DC converter which will take anything up to 40 volts and convert it down to 5 volts. It's in a massive 24 pin package, but it's absolutely brilliant. It's basically a 7805 in a big package, but doesn't waste power. I totally dig it for dropping 9V down to 5 for my robots.

                          For doing 9 volt batteries, you may want to check out the LM2940 from
                          National. It comes in a TO-220 package (same as 7805), can handle 1 amp,
                          and can handle up to 26 volts input.

                          It does require a pair of external caps, but it is super-efficient, and I
                          use it for all my bots.

                          Later,
                          Jon

                          --------------------------------------------------------------
                          Jon Hylands Jon@... http://www.huv.com/jon

                          Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
                          http://www.huv.com
                        • Aaron
                          ... ??? The LM2940 is a linear regulator, so if I try to draw an amp at 5 volts on the output, the regulator will waste 4 volts at 1 amp on the input side... 4
                          Message 12 of 15 , Jul 9, 2002
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                            On Mon, 08 Jul 2002 22:48:08 -0600 Jon Hylands <jon@...> wrote:
                            > For doing 9 volt batteries, you may want to check out the LM2940 from
                            > National. It comes in a TO-220 package (same as 7805), can handle 1 amp,
                            > and can handle up to 26 volts input.
                            >
                            > It does require a pair of external caps, but it is super-efficient, and I
                            > use it for all my bots.

                            ??? The LM2940 is a linear regulator, so if I try to draw an amp at 5 volts on the output, the regulator will waste 4 volts at 1 amp on the input side... 4 watts of power. Not that we could really draw an amp for more than a couple of microseconds from a 9 volt battery. <grin>

                            There are some nice switching regulators which come in the to220 package, but I'm too lazy to get some inductors and whatnot to make them work. That's why I live with the massive package of the lm2825.... it has it all built in, just plug and play...

                            Aaron
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