Zimo additional loco light problem

[Jim M]

Hi folks, first post here for nine years (!) as generally I can solve issues without having to pester people, but this time I've definitely reached the limits of my knowledge!

 

I have a H0 scale loco that came equipped with a Zimo MX645 (Plux22 plug) - this works fine, no problem there. The chip is plugged into a fairly complex PCB which has ribbons at either end to supply the front/rear lights etc. which are on their own mini-boards. Again, all works great.

 

I want to add an LED to the loco which is independent of the direction of travel, so (I think) this rules out powering it from one of the existing lighting outputs, as they seem to feed into a complicated circuit on the PCB (which enables the "directionality" I guess) and I don't fancy upsetting that fragile ecosystem.

 

There are a few unused pins on the chip - according to Zimo's (almost unfathomable) spec sheet they are as follows;

• Pin 6 (positive for "stay alive" functionality?)
• Pin 9 (common pos)
• Pin 21 (aux 6)
• Pin 22 (aux 7)

 

So my questions are; Can I achieve what I want using one of these available pins? And if so, will I be able to "switch" the pin on and off with my NCE PowerCab without having to edit the project on the chip? I can probably live with the LED being "on all the time", but one problem at a time...

 

For the avoidance of doubt, I can solder and hacking electronics does not phase me, I'm just hoping someone with much more experience of these things can tell me whether this is feasible or a complete non-starter, in which case I will happily admit defeat!

Edited June 21, 2021 by Jim M

[jpendle]

Hi,

 

You can change any of the Function Outputs, or aux outputs if you prefer, on a Zimo chip to be directional or not. So you can use any unused Function Output such as Pin 21 or Pin 22, which are FO's 6 & 7.

As long as FO6 and FO7 are not used on the PCB that is inside the loco you should be able to wire a suitable LED circuit and do what you want, you can also set the output voltage on any function output so that it's feasible to wire in an LED without a current limit resistor.

 

You can change how any Function Output works by using either Swiss Mapping (kind of complicated) or CV's 125 to 160, special effects for function outputs.

 

Regards,

 

John P

[pauliebanger]

12 hours ago, Jim M said:

Hi folks, first post here for nine years (!) as generally I can solve issues without having to pester people, but this time I've definitely reached the limits of my knowledge!

 

I have a H0 scale loco that came equipped with a Zimo MX645 (Plux22 plug) - this works fine, no problem there. The chip is plugged into a fairly complex PCB which has ribbons at either end to supply the front/rear lights etc. which are on their own mini-boards. Again, all works great.

 

I want to add an LED to the loco which is independent of the direction of travel, so (I think) this rules out powering it from one of the existing lighting outputs, as they seem to feed into a complicated circuit on the PCB (which enables the "directionality" I guess) and I don't fancy upsetting that fragile ecosystem.

 

There are a few unused pins on the chip - according to Zimo's (almost unfathomable) spec sheet they are as follows;

• Pin 6 (positive for "stay alive" functionality?)
• Pin 9 (common pos)
• Pin 21 (aux 6)
• Pin 22 (aux 7)

 

So my questions are; Can I achieve what I want using one of these available pins? And if so, will I be able to "switch" the pin on and off with my NCE PowerCab without having to edit the project on the chip? I can probably live with the LED being "on all the time", but one problem at a time...

 

For the avoidance of doubt, I can solder and hacking electronics does not phase me, I'm just hoping someone with much more experience of these things can tell me whether this is feasible or a complete non-starter, in which case I will happily admit defeat!

 

Hi Jim,

 

Yes, you can achieve what you wish, but you will need to change a few CVs. There are two aspects to complete.

 

1. Physical connections
 

2. Mapping the selected Function Output to an F key so that the feature can be operated.

 

The physical side.

 

Take a positive feed from Pin 9 and a the return to either pin 21 or pin 22 and connect to your LED, remembering to add a suitable series resistor to prevent over-current and provide correct dimming.

 

 

Mapping.

 

In order to operate the LED you will need to map the physical function output (6 or 7) to a function button/key. Swiss Mapping is what you will need to use. It's more difficult to explain than it is to use. The instructions in the ZIMO small decoder manual serve to complicate things even more than necessary.

 

First locate an unused F key in the project. The functions list or equivalent should provide this info, if not, try each until you find one which has no sound or function already assigned. (if you can't find one, come back as there are options, but as you say, one thing at a time...).

 

Let's say the free F key is a number represented by 'X'.

 

Use ZIMO Swiss Mapping to assign your selected Function Output to F key 'X' as follows:

 

First, read some of the CVs listed below to ensure that you are not about to over-write existing mapping within the sound project. Continue down the list below until you come to one with value 0 (it could easilly be the first one you try!)

 

CVs 430, 436, 442, 448 and so on (add 6 to previous) up to 502

 

Lets assume that CV430 = 0, i.e, it's not already assigned).

 

Change CV430 = 'X' (a number between 0 and 28 whci you have determined is not assigned).

 

Make CV432 = the number of the Function Output you have connected to. This will be either 6 or 7.

 

Make CV434 = the number of the Function Output you have connected to. This will be the same value as used in CV432.

 

(If you want me to tell you the specific CVs and values to use, I'll need to know which F key you wish to use to control the LED, which is the lowset CV number in the list above which has value 0 and which FO you have connected to).

 

This will give you an LED which can be switched on/off with F key 'X' in either direction. If you want to add effects to this e.g. fade in/out, flicker, strobe and so on, you will also need to change values in CV 132 (for FO 6) or CV159 (for FO7), but that can be done later.

 

If you get 'lost' when doing the above, a decoder reset CV 8 = 8 will restore all CV settings to those of the original sound project, so there's no danger of losing sounds from the decoder.

 

Best regards,

 

Paul

 

 

[Nigelcliffe]

Additional to Paul's explanation: also need to find FO6 and FO7 in any function mapping and turn those off first.  (Likely to be CV39 and CV40, but may be different if sound project writer set them to anything else).  

 

If Paul's explanation of Swiss Mapping makes you go "wibble", then its all drawn out in JMRI/DecoderPro (need latest "test" release to get all the Swiss Mapping features), and just a matter of selecting things from drop-boxes.   That also offers features to dim the output if the LED is too bright directly from the Swiss Mapping settings. 

 

Strongly recommend reading values from decoder before changing anything, that will reveal which, if any, groups are currently active.  

 

 

( The DecoderPro table took a few weeks back in January/February to complete, the Zimo manual on Swiss mapping is awful.   The English version is wrong on a few details, the German is just as confusing without the mistakes.   The DecoderPro file should be correct - I spent long enough making sure it worked ).  

 

 

- Nigel

 

[Jim M]

Wonderful answers chaps, thank you very much. Sounds like I have my work cut out! I will investigate your suggestions and let you know if anything catches fire

[bigal10]

Hi folks, sorry to but in, but this chain is the nearest to my query.....

 

Is it possible to 'Daisy Chain' lighting effects in CV's 125 to 160?

 

For example to have Cab Lights on F1 and F2 which extinguish on the loco moving off, but also to fade in and out as required?

 

Or is there another way on a Zimo 644D 21-pin?

 

Alan Richards.

(Confused of Bury)

[pauliebanger]

No, Alan, with standard ZIMO CVs it's either/or.

 

Best regards,

 

Paul