ID an RC chip?

[Don Bruder]

Hiya folks...

Looking for information on a chip out of a radio-controlled car. This
looks to be the receiver/decoder chip. The transmitter contains a
simliar chip, with "RX replaced by "TX" - Obviously, the two chips make
up the heart of the encode-TX/RX-decode circuitry.


Here's everything I've got on the beast

It's a 16 pin SMT DIP
-----------------
| RX6C |
| [logo] A9112 |
| o 1CA |
-----------------

The [logo] makes me think "reindeer with a moustache" - As close as I
can get with ASCII art, it looks something like this:

U U
\_ U _/
\ /
/// RMC \\\

The letters "RMC" are literals - the groups of "///" and "\\\" are more
curved, looking a lot like the ends of a rainbow sticking out from
behind the "RMC".

Anybody know where I can find information about this chip and its pinout?

Google is coming up empty for me on all variations on the
letters/numbers that I try putting in, and RMC returns so many hits I
don't even know where to start - suffice it to say that the first 2
pages worth of results for RMC had nothing that looked even slightly
related to electronics... Metals, casting, plastic model kits,
bearings... But nothing like radio control electronics.

Anybody got any advice?

FWIW: It comes out of a 49 MHz Radio Shack RC car, the so-called
"Dynamos Wicked Wing". (Catalog number 60-4395)

I'm also looking for some assistance in changing the board it's on from
a "car" controller to a digital logic level signal source - IE, If I lay
on the "forward" button, I want "pin 1" to be a logic high, and pin 2 to
be a logic low, and if I hit the "reverse" button, I want "pin 1" to be
low, while "pin 2" goes high. ("pin"s in this case being the final
outputs after any massaging by circuitry I may need to add.)

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Don Bruder]

In article <1109684913.080256.272920@o13g2000cwo.googlegroups.com>,
larwe@larwe.com wrote:

makes me think "reindeer with a moustache" - As close as I

can get with ASCII art, it looks something like this:

U U
\_ U _/
\ /
/// RMC \\\

The logo is meant to represent a crab rendered in vectors, and the
company is Realtek.
They used to have the datasheets for this chipset
up in the public areas on their site, but last time I checked it wasn't
findable. You might have better luck. www.realtek.com.tw.

BINGO! The logo on that page is an exact (but larger and easier to see)
clone of the logo on the chip. I'd say that puts me in the right place
to "start digging". Thanks!

I'm also looking for some assistance in changing the board it's on
from
a "car" controller to a digital logic level signal source - IE, If I
lay
on the "forward" button, I want "pin 1" to be a logic high, and pin 2
to

The output of that chip is practically what you want already. It's a
2-channel non-proportional controller.

Yep, that would be absolutely perfect, seeing as the whole TX/RX package
is intended to be the remote "up/down/left/right" button-pad used to
control a pair of stepper-motor drivers that will give me pan/tilt on a
powered camera mount.

As it exists right now, I've got 6 buttons and a power switch on the TX
- Buttons are forward, reverse, left, right, and the unlabeled buttons I
call "Trick1" and "Trick2" that control a "transform/detransform"
feature of the car that operates independently of any of the rest of the
controls.

Calling the motors "D1", "TM", and "D2",, and their associated
connections on the board "Pins" 1-6, here's what I have:

CW = clockwise motor rotation when looking at shaft end of motor
CCW = counterclockwise motor rotation, as above
s = stopped

"+" = connection on the board shows V(supply) to ground
"-" = connection on the board shows 0 to ground
x = inactive/indeterminate/irrelevant/don't care

"pin" = semi-arbitrarily named connection point on board
M = motor
d1 & d2 = drive motors which usually operate in tandem
tm = "trick motor", which always operates alone.

Activated control(s) on transmitter
+--+-+-----+-----+---+---+---+---+---+---+----+----+
| |p| | | | |fwd|fwd|rev|rev| | |
| |i| | | | | + | + | + | + | | |
| M|n| fwd | rev | L | R | L | R | L | R | t1 | t2 |
+--+-+-----+-----+---+---+---+---+---+---+----+----+
|d1|1| - | + | - | + | - | x | x | + | x | x |
| |2| + | - | + | - | + | x | x | - | x | x |
| | | CW | CCW | CW|CCW| CW| s | s |CCW| x | x | rotation
+--+-+-----+-----+---+---+---+---+---+---+----+----+
|tm|3| x | x | x | x | x | x | x | x | - | + |
| |4| x | x | x | x | x | x | x | x | + | - |
| | | x | x | x | x | x | x | x | x | CW | CCW| rotation
+--+-+-----+-----+---+---+---+---+---+---+----+----+
|d2|5| + | - | - | + | x | + | - | x | x | x |
| |6| - | + | + | - | x | - | + | x | x | x |
| | | CCW| CW | CW|CCW| s |CCW| CW| s | x | x | rotation
+--+-+-----+-----+---+---+---+---+---+---+----+----+


And before anybody says "You already know all this about the
board/motors, so why not use them as-is, just mounted to your project?",
allow me to say "That's a no-go" - Nowhere even *SLIGHTLY* close to
enough strength in the existing motors, and besides, I want STEPPERS
doing the driving, so that I can position the head accurately and
repeatably - think "presets" that a serial interface from a computer
could drive. Without going *WAY* overboard on the complexity I'm willing
to indulge in for this project - As in "How about a nice game of "Let's
design a servo-control system from scratch?"- that just plain can't be
done with conventional "It is/isn't spinning" motors.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Don Bruder]

In article <4224507a$0$28985$e4fe514c@news.xs4all.nl>,
"Jeroen" <none@none.com> wrote:

Probably the chipset is from UMC, but it could be an obscure chinese brand
as well. I think it's impossible to find info on it.

Well, someone else managed to clue me to the fact that the logo is for
an outfit that calls itself "RealTek", now I need to find the datasheet
if it's available. Been to their website, but haven't spotted the DS
yet. I'm thinking I may have to actually pick up the phone and talk to
somebody there to get the info I need.

I have dismantled a cheap China made R/C car, which contained a RX7/TX7
chipset in THM. The board contained discrete transistors to drive the motor
and steering solenoid, so the outputs can be found on the chip; a little
scope probing should tell which pin does what.

Haven't gone as "deep" as trying to probe the beast for what the pins
are yet, but I've got a handy little chart of what happens with the
motors when the various control buttons are pressed. It's in my other
response in this thread if you're interested. I'm pretty well certain
that it's a trio of H-bridges being activated for the proper motor
rotations, but trying to trace a double-sided 1.25 by 0.75 inch SMT
circuit board that's packed so dense that it's difficult to see the
board itself through all the components is... "interesting"...

I wouldn't use this kind of circuit for secure things

Not a problem there - final application is going to be a "zero security
issues possible" item. Specifically, a motorized pan/tilt head I intend
to mount a wildlife observation camera on. Assuming somebody else
actually gets close enough to control it with a similar TX unit, and has
a receiver and portable display unit to show them what the camera is
seeing, the absolute worst-case scenario I can come up with is that they
may be able to pinpoint its location and "help it grow legs". I would,
undoubtedly, regret the loss of it if that were to happen, but it's not
really what I'd call a "security risk". Particularly since it's going to
be operating "out in the backside of beyond", in an area where 95% of
the neighbors (such as they are...) are technologically illiterate - No
insult intended, but most of these folks wouldn't recognize it as
anything more than a somewhat interesting looking pile of weird junk.
(assuming I leave it "plain", rather than trying to "dress it up in
camo", which is my current plan)

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.