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Beppe Giannini
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Thanks a lot, Søren - I think I got it (apart from debugWire in-circuit emulation !!)

So, will your motor controller have current limitation (PWM override) as a way of defining car classes ? Or is there another output overcurrent protection ?

I realize on a normal set-up the potential for a downstream short is limited - but there may be other people in addition to myself whose brain has gone into hibernation - on the other hand, no protection would generate additional sales


Ciao

Beppe
 

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Soren Winkler Rasmussen
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Hi Beppe
QUOTE (Xlot @ 18 Jan 2005, 08:57)Thanks a lot, Søren - I think I got it (apart from debugWire in-circuit emulation !!)Great.


... the in-circuit emulator (ICE) is a debugging equipment you attach to the microcontroller, that allow you to download software, view the internal registers, RAM and ROM, singlestep your program one instruction at a time and set breakpoints when the code reaches a certain point.

In short, the ICE allows you to look inside the microcontroller and change registers and program execution ... a very nice tool for debugging.

... and an Olimex AVR ICE cost only $39,95.


QUOTE So, will your motor controller have current limitation (PWM override) as a way of defining car classes ?Yes, the current limitation is software configurable ... that's the big advantage by using this method compared to the hardware controlled current limitations.


QUOTE Or is there another output overcurrent protection ?Apart from the software current limitation, the MC33887 motor controller also have a built in hardware current limitation. The hardware current limit will cut in at 6,5A, and is there to protect the motorcontroller from overload (such as short circuits), if the software limiter isn't fast enough.

QUOTE I realize on a normal set-up the potential for a downstream short is limited - but there may be other people in addition to myself whose brain has gone into hibernation - on the other hand, no protection would generate additional sales
Combined with a built in thermal overload protection, the MC33887 should be well protected from any kind of abuse such as short circuits and other overloads. In all practical terms, the MC33887 should be "destruction proof".
 

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Hello Soren,

as mentioned here in the Forum (CarDCC Status Thread), I'm absolutely impressed by your CarDCC concept. I read the hardware requirement specification about four
times and now I'm understanding most of your ideas.

But to some issues I've questions, comments or suggestions
. At first I thought it would be the best to post that directly in the SlotForum, but it would be difficult to describe the references to this specification document. So I decided to put in the comments directly in the specification with red colored text.
By no means, I want to be impolite but this is the easiest and fastest way to tell you my opinion about the topics. I hope you comprehend my feedback not negative, the only thing I want to do is to talk about possible problems that I saw in the concept, alternative solutions or sometimes "nice to have" features that might be integrated in the future.

How can we exchange this document? If you give me your email address via Forum Privat Mail i can send you the specification including my feedback.

Best regards
Guenter
 

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Hi Soren

Have just revisited the CarDCC thread. Having spent some time reverse engineering the SSD Powerbase and in car electronics, there are not suprisingly a lot of similarities between SSD, CarDCC and of course the NMRA DCC system where it all comes from.

Seeing what is and is not there provokes numerous ideas for additions and improvements. At that point one has two choices. Take all the ideas and produce a better system. Or produce some add ons and improvements to an existing system.

So an idea. Have you, or anyone else, enthusiasm for a SSD compatible mode for CarDCC. Hardware would probably need no changes. All the change would be in the software. Existing cars could be used with slightly reduced functionality, but with the benefit of an enhanced control system.

Alternatively the CarDCC car controllers could be used with the existing SSD Powerbase with the benefit of better performance and control.

It would be a stepping stone approach with parts being interworkable, but still leaving open the prospect of a full CarDCC system in the future.

What do you think, could be a best of both worlds way forward?

Finally a detail on your in car electronics. On the cct is the PWM signal for the rear lights generated in the microcontroller, and then brake from the motor driver? Also a detail comment. I realise you can add a lighting controller to the car if more inputs and outputs are needed but I feel that more inputs / outputs in the base controller would be of benefit.

Richard
 

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Hello Richard,

I am just in the progress designing a replacement of the Carrera Pro-X car controller. It will be compatible with Sören's CarDCC and Pro-X. We discuss the related items in various threads in the German "freeslotter forum".

Sorry I do not know anything about how SSD works. Do you have a link to a description ? Especially interesting would be the protocol of the data sent from the track controller via the track to the car controller and also how this data is coded on the track supply (i.e. Pro-X uses +17V/GND, DCC uses +xV/-xV).

Concerning the questions about Sören's car controller design my understanding of the schematic is:
The PWM of the dimmed rear lights is generated by the micro controller. The transistor(s) for the brake is/are included in the MC33887 (H-Bridge made by Freescale).

Regards

Juergen
 

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Hi Juergen

Thanks for the reply. Unfortunately I cannot read German so cannot contribute to Freeslotter.

I am having a "Dim" moment on the rear lights.

I can see that PB0 of the microcontroller has a 10K pull up and is connected to -FS of the H-Bridge, which from the data sheet I see is the Fault Status output from the H-Bridge.

However PB0 also seems to be connected to the rear lights? Is PB0 switched between being an Input for Fault Status and Output for brake lights?

I have understood the SSD protocol but it is not documented, just in my head at the moment!

I am not sure what you would call it but the SSD Powerbase has an H-Bridge in the output stage driving both rails with antiphase signals. The 0 and 1 timings are very similar to DCC. (Is this what you call +xV/-xV ?)

Is your Pro-X care controller electrically the same as Soren's but with modified firmware for the Pro-X protocol? Are you going to put both CarDCC & Pro-X protocols in the car at the same time?

Richard
 

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Hi Soren,

One idea, if possible, would be having the option to wire the l/c's on there own circuit.

Say, for the person just getting into CarDCC with 3-4 cars, 30 feet of track, and 4 l/c's ,the l/c's would run off the track. If a person or club has 16 cars,140 feet of track and 10 l/c's, the l/cs can be wired off their own circuit on the controller.

This would help keep signal traffic on the rails at a lower value on larger layouts with multiple l/c's and cars, with less chance of corrupted or lost/skipped info(lap/sector timing).

Best of luck with your project


Sincerely,Gord
 

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Hello Richard,

QUOTE Is PB0 switched between being an Input for Fault Status and Output for brake lights? Yes, correct. The rear lights are used as standard rear lights and also brake lights. in "standard" mode the lights are dimmed by a PWM to get a lower light intensity. In the pause of the PWM the output is changed to input to check the fault status of the H-bridge. During braking the PWM signal is set to maximum to get maximum light intensity.

QUOTE I am not sure what you would call it but the SSD Powerbase has an H-Bridge in the output stage driving both rails with antiphase signals. The 0 and 1 timings are very similar to DCC. (Is this what you call +xV/-xV ?) I think so. Guenter has made two graphics concerning the different data transmission standards.
The first one shows that the voltage at the slot is switched between i.e. +17V and -17V (x=17). This kind of transmission is used by the DCC systems according to NMRA.
The second picture shows the data transmission which is used by Carrera Pro-X. In this case the track voltage is either 17V or 0V.

QUOTE Is your Pro-X car controller electrically the same as Soren's but with modified firmware for the Pro-X protocol? The hardware will be similar but no exactly the same. It looks like it is difficult to get the H-bridge in small quantities here in Germany. And I think a half-brigde is also sufficient.

QUOTE Are you going to put both CarDCC & Pro-X protocols in the car at the same time? I am not sure if there is sufficiant FLASH memory available to keep both protocols. But I will include a possibility to upload different firmware versions.

Regards

Juergen
 

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Soren Winkler Rasmussen
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Discussion Starter · #29 ·
Hi Richard

QUOTE (RichG @ 1 May 2005, 12:09)Have you, or anyone else, enthusiasm for a SSD compatible mode for CarDCC.I think it's a good idea.

I haven't given it a lot of thought, because I don't know very much about the SSD dataformat.

I agree though, that the only difference would be software. We're planning to build a software download facility into the CarDCC track controller. This could also be used to load new functionality into both track controller and car controller.
QUOTE Alternatively the CarDCC car controllers could be used with the existing SSD Powerbase with the benefit of better performance and control.That should not be a problem seen from the hardware point of view. You'd only need to adopt the SSD protocol and add the transmission of the IR-LED identification sequence.
QUOTE What do you think, could be a best of both worlds way forward?It certainly could.

I'm currently working on the CarDCC protocol, but a SSD compatibility mode would be a nice feature to add. It should be possible to make software versions for both CarDCC, SSD and Pro-X compatibility. That way every user has full flexibility from the same hardware.
QUOTE On the cct is the PWM signal for the rear lights generated in the microcontroller, and then brake from the motor driver?Correct, but the the motor driver brake signal is generated in the microcontroller and fed to the motor through the motor driver.

The only motor PWM signal that is automatically generated in the motor driver hardware, is the automatic overload protection system. It has priority over the PWM controls from the microcontroller.
QUOTE I realise you can add a lighting controller to the car if more inputs and outputs are needed but I feel that more inputs / outputs in the base controller would be of benefit.I agree.


With the current design I have tried to balance functionality, size and cost. As the Signal Controller (former Light Controller) is really small (6x34mm), and will easily fit into a car, I thought it was an acceptable compromise. You can also add more than one car controller to a car.

The current car controller has two light control outputs that can be used for various control functions such as brake lights, rear/brake lights, exhaust flames, glowing brake discs and safetycar flash lights.

The downside of adding more outputs are:
-The size of the car controller will be bigger than 15x22mm, and difficult to fit inside an F1 car.
-All the cars that don't need more than two light control functions, will be unneccesarily expensive because of added functionality they're not using.

Extreme example (slight exaggeration ahead) ... You have 20 ordinary cars and a Coca-cola truck
:
It would be cheaper to put a lot of light controllers in the truck, and keep the cost of the ordinary cars down.
 

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Soren Winkler Rasmussen
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Discussion Starter · #30 ·
Hi Gord
QUOTE (Newbie1/32 @ 2 May 2005, 10:48)One idea, if possible, would be having the option to wire the l/c's on there own circuit.Yes, its possible.

You will need an extra track controller, and then you'll need to wire the LC's separately instead of connecting tham to the track.
QUOTE Best of luck with your project
Thank you very much.
 

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Hi Soren,

Sounds like you have thought about darn near everything to make a truely all around system
How is your prototype coming along? May I pry and ask when it will be available,and will it be more affordable to the general public than Davic?

Best regards,Gord
 

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Soren Winkler Rasmussen
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Discussion Starter · #32 ·
Hi Gord
QUOTE (Newbie1/32 @ 6 May 2005, 19:18)Sounds like you have thought about darn near everything to make a truely all around system
Thank you

QUOTE How is your prototype coming along?I'm currently working on the Track Controller. The CC seems to be ok, but I can't know for sure until I have the TC up and running. I'm starting out with a very basic system that will only allow you to control car speed and download new software. The plan is then to release a steady flow of software for download as new features are added.
QUOTE May I pry and ask when it will be available,and will it be more affordable to the general public than Davic?I can't really say for sure, but I'm hoping to have the basic system running before the summer holidays. The reason I can't be more specific is that there are many unknowns: how many problems will I meet?, how much spare time will I have?, will I have to redesign parts of the system?.

I'll keep you posted though when I'm closer to having a working system.

I've made a preliminary calculation of the component prices here ... look for the BOM.xls attachment to my post on 05.05.2005.
 

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Is it likely to be able to be used for routed tracks??
 

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I sent Soren a pm to see if he can give us an update on his project haven't had contact for a while so hope everythings ok for him.

Gord
 
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