Elmo Live Dissected

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RetroPlayer
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Nocturnal,

That's the problem. After I buy one for her and see it moving around, I will want to hack one. :) That's how it always works.

Nocturnal
Nocturnal's picture

I don't have a niece, so thats not a problem for me... yet. I'm going to be an uncle in January.

If I am reading seviks description correctly, any file, as long as it is in the root directory (ie only parsing the root directory).

I was more interested in writing files at the time, not reading them (I also wanted FAT32, though I would have settled for FAT16). I also had less than 1024 bytes of SRAM left.

I've been much happier since I got an ATMega128 board from futurlec a while back. I keep meaning to buy more.

milw
milw's picture

  

BREAKING NEWS - Elmo shredded by marauding cat! Neighbor says 'It was horrible, just horrible. Elmo just wanted a big hug!'

Is there a correlation between cat ownership and our common interest?

sevik
sevik's picture

about FAT reader:

You dont need to parse whole fat, you only need it to find next cluster with data and this is done in this implementation.

This implementation does not handle recursive searching of directories.

For buffers - if you can read your sdcard/other media byte-by-byte and feed data for processing same way - you can go without buffers at all.

FAT parsing part just need to read 2 bytes at known offset. MBR/BPB parsing code can be done this way too.

But I think at least one sectorsized buffer you will need anyway for further processing...

For writing all is more difficult of course :)) But I have plans for writing too :))

RetroPlayer
RetroPlayer's picture

milw, seems that way. 2 cats (adult and kitten) and a boxer here. If I had my kitten in the workshop when I was taking pictures, they would have been pictures of him pinning it on the floor fighting it. He is a "little monster" that Elmo couldn't compete with. :) Even my 120lb boxer runs from him.

I don't usually let him hang out in my workshop because he throws things off my shelves and benches and chews everything up, especially whatever I am paying attention to instead of him.

Too cute to get rid of, though.

Nocturnal
Nocturnal's picture

That looks more like a rogue Elmo trying to learn how to hug a cat (a challenging endeavor).

:) I wouldn't write my own Fat32 handler, I'd borrow someone elses. There are one or two other ones listed on avrfreaks, but you have to register to view projects.

RetroPlayer
RetroPlayer's picture

Nocturnal,

Sevik lives for this kind of stuff. I have no idea how he works so fast. I think his cat helps him out.

He can crank out huge amounts of code in just an hour.

GWJax
GWJax's picture

RetroPlayer said: Nocturnal, Sevik lives for this kind of stuff. I have no idea how he works so fast. I think his cat helps him out. He can crank out huge amounts of code in just an hour.

Retro in order to crank out a huge amounts of code in a short time he must have a huge library that he uses else he types as fast as he thinks, hehe. I love just sitting back and watching this robot evolve to what ever you guys have instore for it.. It gives me a break which is a good thing :)

 

Jax

sevik
sevik's picture

:))) Really I borrow all code that I see :))

And having /usr/include and /usr/src from FreeBSD is helpfull too :))

Most of structures and handling of them was done based on fat sources of freebsd :)) I just have to strip unneded code and reorganise it for my limited task :))

sevik
sevik's picture

I always very afraid of phrases like this: "and is easily expandable for use with other devices on any platform." :))

Generic frameworks are good when you have unlimited (as in PC) resources :))

This FAT reader is just ~250 lines of code including ~100 lines of structures definitions and ~50 lines of low-level code for UART/etc :))

http://sevik.org/fat_reader.c

sevik
sevik's picture

I have looked at speaker output with scope

Speaker driven with PWM, pwm period is ~20uS (50kHz).

It's not filtered, so we can get original digital values of output by tracing it.

sevik
sevik's picture

Motors driven from main cpu with just levels, no PWM.

So Elmo can't be slow, only fast and expressive :))

GWJax
GWJax's picture

sevik said: Motors driven from main cpu with just levels, no PWM. So Elmo can't be slow, only fast and expressive :))

Yes but with the help from another cpu and some programming  a PWM signal can be done as long as there are no sensors that are tracking the time it takes to get from point A to B for the motors. This would be a really great hack and an asset to Elmo with slower motors such as a wake up and streach routine.. Just had to put my 2 cents in hehe.

 Jax

eightniner
eightniner's picture

Hi Retroplayer, thanks to your great info!

my 13 months old son has badly injured Elmo. Now Elmo's right knee rattle when he is trying to cross his leg. Elmo's jaw doesn't move anymore when he talks but again rattle instead. (Elmo's jaw can open while he is looking upward though). I followed your way to open his head. All the springs, guide pins and cams are okay. I put them back but the rattling continues. It seems to me the gear mechanism inside his neck is the culprit (it is the source of the rattling noise after further investgation). Any idea what else I can try please??

RetroPlayer
RetroPlayer's picture

eightniner,

You are going to need to get inside the torso. The first thing I would look at is the encoder that I was showing in my last couple of posts. It is just below the neck line just inside the torso.

It should be facing forward when the head is idle. Remove the motor by just loosening the two screws on the bracket holding it and pull the motor out. Now you can move the head around freely and it will rotate the encoder. Position the head so it stops clicking and the encoder is facing forward, then put the motor back in. Should be fixed.

It's unlikely that your son broke any gears, as the cams and levers would have broken first and most of the gearing has spring-clutches on them. The clicking or rattling noise is caused by misaligned gears. I encountered this when I was experimenting with it to figure out the encoder above. I just had to remove the motor, move the head back to the idle position and then install the motor again and all was fine.

You will probably have to do the same with the knee, but the legs are a bit more difficult to get into. Mine is clicking right now, too, and it was caused by forcing movement manually while he was not powered.

blkmagic
blkmagic's picture

Not sure if you guys would be able to help me on this. But after barely 3 days with Elmo Live, my daughter has managed to break it. She did it by pressing both the stomach and back buttons simultaneously while Elmo was telling a story. Now Elmo stops at the point where the buttons were pressed and I couldn't figure out how to reset the thing. I was able to reproduce this in the "elmo loves you" sequence as well. The manual says to leave it turned off for a while to reset it, and I've left it off overnight to no avail. Any suggestions would be appreciated.

gugus651
gugus651's picture

I think elmo is prettyer whitout his fur. :)

sevik
sevik's picture

I cant' reproduce this...

Are you sure you can repeat it ?

Really, Elmo does not have any nonvolatile storage, and cartride(ROM) content cannot be modified using existing electrical interface.

May be it's just some physical damage of one of gear boxes when she pressed them hard enought :))

blkmagic
blkmagic's picture

@ sevik
Yes. Because originally this only happened while Elmo's telling the Giant story. Then I tried it myself in the "elmo loves you" routine and the same thing happened again. It would stop every time at the exact same point where I pressed the stomach & back button simultaneously. All the movements are fine and there is no unusual noise at all. When Elmo stops it would straighten itself up and raise the arms as well. Even with the plastic tab in the demo slot, the "elmo loves you" routine would not finish.

Either way, given what u know about the device, what do you think would cause this and how can I fix it? Btw, y are there 2 slots for the plastic tabs? Do they in any combination perform a reset on the device?

Thanks

RetroPlayer
RetroPlayer's picture

blkmagic,

Can you provide video of this behavior? Just post to youtube and provide the link here under advanced mode.

Re: the two slots on the bottom of the foot. There is only one switch inside, even though there are two slots and room for two switches, really. This is connected as an input to the main board called "Try me" and the input is no different than any other button on Elmo (meaning, it is not a reset, just another mode.)

RetroPlayer
RetroPlayer's picture

blkmagic said: When Elmo stops it would straighten itself up and raise the arms as well.

This might be the smoking gun right there. This is Elmo resetting to the neutral position. It usually happens when you first power him on, or he switches to another mode. Perhaps you have a stuck button? Either the back or tummy? Mine is completely disassembled right now, or I would try some things for you. Maybe Sevik can try simulating a stuck button for you to see if it matches your description. A video would still be helpful to make sure we understand what you are experiencing.

MelanieJLC
MelanieJLC's picture

i hope i came to the right place for help - our Elmo Live is making a horrible clicking sound when any button is pressed - eventually he will go into sequence with song or action but the clicking lasts about 5-10 seconds prior to each time. it doesn't sound

MelanieJLC
MelanieJLC's picture

our Elmo Live is making a horrible clicking sound when any button is pressed - eventually he will go into sequence with song or action but the clicking lasts about 5-10 seconds prior to each time. we think it might be in the right leg as it just seems to dangle freely and seems very loose. any ideas??

blkmagic
blkmagic's picture

Hi Guys,

Thanks for the suggestions. But I actually solved the problem in the simplest way possible...brand new batteries. Unlike other electric toys, apparently when Elmo's low on juice, it doesn't talk or move slower, it just stops 1/2 way through the act. I'm guessing the first time I tried swapping batteries, they were drained since they been sitting on the bookshelf for a while.

Anyways, thanks for all your suggestions into this!

Brandi
Brandi's picture

Hi there!

My daughter, Lily, just got Elmo Live for Christmas and loves it. Well the first day she got it she was hugging it so tightly that she did something to the mouth and now it clicks when it's talking and the mouth doesn't move when he's speaking. It does when he is laughing though. Can you help me figure out how to adjust the mouth piece so that it works again.... I would really appreciate it. Thank you!

GWJax
GWJax's picture

Hey Retro, I think you'll be busy this coming next few months with helping out people with the Elmo, This makes me want to go and get one so I can help you out with alot of these help lines..

Jax

GWJax
GWJax's picture

OK an up date, I broke down and bought an Elmo Alive today so now I can help you out Retro in the up coming months on the simple and hard breakdowns of this little guy so you wont be over whelmed with questions on them. Just give me a week to get use to what I see and take it apart by every screw and stud shaft holding it into place.

Jax

RetroPlayer
RetroPlayer's picture

Thanks GWJax. I have been away from the site for awhile. I am experiencing some medical problems (nothing serious) that have been exhausting me a little.

Brandi, I noticed my Elmo was clicking after moving the head manually alot. What I discovered was that the encoder was getting misaligned. Elmo's mouth opens when his head moves forward, or rotates up.

First, do you hear any rattling inside the head at all? And can you move the head forward and back, manually? If so, does his mouth open when you push his neck forward?

RetroPlayer
RetroPlayer's picture

MelanieJC,

His leg does dangle freely. That is normal. It is driven by cables and pulleys. The cable only becomes tight when he is sitting with his leg crossed. The clicking noise is the same as I mentioned in my last post to Brandi. It seems to happen when he is misaligned and doesn't know where his body is. Unfortunately, if it isn't in his head, you have little chance of fixing him without opening him up. The reason is because the arms and legs are mostly cable driven, and are normally just loose. The exception is that the left leg is geared. It moves only when he is sitting or standing.

Does any of his movement seem like he is struggling? You should feel some unusual vibration or chattering in the limb that is having the issue.

jsaugustyn
jsaugustyn's picture

Hey, this is a fantastic thread. My daughter just got an Elmo Live tonight, and after some untender mercies from her brother I'm getting the clicking while talking problem noted above. I can articulate his neck - pushing forward opens the mouth, as does a full tilt back. Nothing rattles inside the head.

The misaligned encoder makes sense, but is there any way to re-align it without pulling off the fur?

Thanks!

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