Dangerous Prototypes

In development => Project logs => Topic started by: hak8or on August 15, 2011, 08:28:51 am

Title: Rover, gutting a Sony Bravia, and yesterday (56k warning)
Post by: hak8or on August 15, 2011, 08:28:51 am
Hello everyone! :)

I am working on making a rover thing so I can finally have a mobile car that I can use for things such as just driving around, scaring my cat, and learn some things about mobile electronics such as battery power, power usage, motor drivers, and wireless data transmission. So far, I have the chassis found out for sure, it is from a toy car I found lying on the side of the road for garbage collection. I, as any tinkerer would have done, took it home to see what I could use from it. :P

This is what I will be using for the robot chassis.


The battery I will be using to power it, also taken from someone else's garbage. I think it should be enough to last (7.5 Ah and 12V) for a while, it is very durable, and should be able to handle the peak currents for the motors because it is (I think so at least) a lead acid battery.



One battery fits in snugly. I might add in a 2nd because I have seven of these batteries lying around, might as well use them for something.


I do not know what micro controller I will be using for sure, but most likely it will be either a pic24F or a pic18f452, since I have both lying around.
*have to be added in*

Now, here is what I am going to be using for data transmission, since I always wanted to try using this as well as I have a few cordless phones lying around because they are so abundant on trash days. This is what it looks like on the outside, simple one handset phone with a base station. Unfortunately the headset battery was missing, but I was planning on running the entire robot off the battery anyways.


Here is what it looks taken apart.


You can actually see the RF part of it that handles the wireless data transmission. It is encased in the metal enclosure, to prevent the RF from flooding out in the wrong places, which would cause problems with the FCC certification. I am not sure though, so anyone feel free to correct me if I am wrong!


A close up of the module. I would want to try to just de solder the module and connect directly to it instead of through the board, but I have no idea what the pin outs are yet. I also cannot find any identification stickers or other information as to the make or model of the module. Also, a quick thing I have noticed on a large majority of boards I have seen for the past few months, almost all of them have tear drops instead of the simple trace to component. Is it usual to have components with tear drops instead of the simple trace to component, or am I into some lucky streak?


Side of the RF module. It is clear that the module is the metal enclosure on a PCB, which was then soldered onto another PCB. I have never seen such a thing in the wild. Is it normal to include a pre engineered turn key solution in large scale production items? I thought these types of modules are used only in low quantity items, or prototypes.


Here is something that really caught my eye right away when I flipped the board that had the RF module on it. An Atmel MCU! Any ideas for what the white this that surround part of the Atmel chip are meant for? I think it may be to cause more difficulty reverse engineering the board or something like that, because it is very hard to find where the via's or traces go under the white solder mask/silkscreen. Also, the sticker thing on the chip to the left of the Atmel chip is very unusual, I never saw something like it before. You think that it is something soft and you can peel it off, but it turns out to be some very hard material, that feels like sandpaper almost. I have no idea what it is meant for. Is it meant to keep someone from finding out what chip it is, or to help give off heat from the chip? I have no idea, any suggestions would be welcome.


I tried to get the sticker thing off the chip because I was incredibly curious as to what it was hiding. I feared that it will be nearly impossible to get it off without damaging the chip, but it turned out that a just tapping it with a Flathead will result in it chipping away. Very gentle tipping mind you. This causes me to further have no idea what it is meant for, if it is so easily taken off without damaging the chip.


A minute or two later of Flathead tapping and a tissue gives me this. I have yet to google for the datasheet or this chip or find anything out about it, but I guess that it takes the analog value from the microphone or land line, converts it to digital (like an ADC), and then does some compression or other things that a Digital Signal Processor would be good for.


The cat that will get horrified at a driving rover thing that is about the same size as itself. He really likes to sit in the chair I just stood up from for some reason, no idea why. Also likes to stare at me doing this type of stuff.


Something else I found on the board was a EEPROM, I guess for holding phone number favorites and stuff like that. I am currently working on seeing what is on the chip with my bus pirate. The EEPROM is a AT24C32AN, here is a datasheet . http://catalog.gaw.ru/project/download.php?id=2843


Here is my bus pirate I am using for getting the contents of the EEPROM. I took the schematic from the original bus pirate, got rid of some stuff, changed some stuff, and made it a bit smaller. I should have used a SMD pic24f, but oh well. I mainly made it to break out a FT232 and practice making PCB's and soldering. This was my first PCB I designed and soldered, and 0402 components were not THAT bad, just need a steady hand and good eyes. :P


I was considering putting my old post into this one, but realized that it would make the first post very very long, so I will just link to it from Hackaday Forum.
http://forums.hackaday.com/viewtopic.php?f=3&t=1023 (http://forums.hackaday.com/viewtopic.php?f=3&t=1023) <-- Stuff I did yesterday (LOTS of pictures)
http://forums.hackaday.com/viewtopic.php?f=3&t=605 (http://forums.hackaday.com/viewtopic.php?f=3&t=605) <-- The Sony Bravia gutting (LOTS of pictures as well)
Title: Re: Rover, gutting a Sony Bravia, and yesterday (56k warning
Post by: hak8or on August 16, 2011, 07:42:57 am
A small update.

Today my basement kind of flooded from all the rain in NYC. It normally does not flood in other houses, but because of my genius neighbor who refuses to repair his wall or his basement, the water flows from his flooded basement into ours through the wall. So I had to sit all day in the basement and get the water out by hand (not enough water to pump out, not little enough to just leave sitting there) with a dustpan and a bucket.

I finally had some time to work with the EEPROM today and I found a mistake in the way I made the PCB for the bus pirate. When I do a self test the 3v3 line shows up as zero, which was expected since I did not connect it. The problem is that I2C mode does not want to pull up resistors or work when it does not have a proper 3v3 reading. That is all very good, working as it should, but I am surprised there is no way to ignore this and go ahead with it regardless of the 3v3 reading. I am currently going to look at the source code for the bus pirate and add in an ability to ignore any 3v3 readings and force it to go along with pull ups.
Title: Re: Rover, gutting a Sony Bravia, and yesterday (56k warning
Post by: hak8or on August 17, 2011, 01:40:22 am
A few things happened today !

I saw a post on hackaday, that caused me to put this to the side a bit and work on a power supply that is capable of high voltage as well as variable voltages. So I will post in this thread some more pictures!

Unfortunately I have not gained any progress with giving the bus pirate an option to force itself to pull up resistors and go along with I2C even though it is sensing zero volts on the 3v3 line. I don't know enough about the bus pirate source code in its current form yet. When I compile the source code (most recent from the bus pirate project on google code) and program the pic24f with my pickit2, I get an error saying that it failed verification at 0x00ABFE. I am thinking that I have the wrong chip selected, or maybe Mplabx is just unhappy with the project or something. :P Will work that out soon. I might as well just solder some jumpers to get the 3v3 sense working properly.

Anyways, I have not included pictures of the chassis or battery, so I am adding them now!
Title: Re: Rover, gutting a Sony Bravia, and yesterday (56k warning
Post by: Sjaak on August 17, 2011, 08:05:54 am
That is the location of the config bits. Try setting them in the code
Title: Re: Rover, gutting a Sony Bravia, and yesterday (56k warning
Post by: hak8or on August 17, 2011, 06:57:19 pm
Thank you for the information Sjaak! I will check the config bits sooner or later.
I have currently shifted all my focus onto the power supply and making a small website.

viewtopic.php?f=19&t=2678 (http://dangerousprototypes.com/forum/viewtopic.php?f=19&t=2678) <-- power supply

http://archive.hak8or.com (http://archive.hak8or.com) <-- nowhere near done yet, learning html as I go right now.