Pin 11 to pin 4 connection

[flavio]

Hope to still find someone in here, since the last post was one year ago.
I have assembled some units of function decoder which are working pretty well. (Ok, there are some minor issues, but nothing really important).
I’m using the 16F630 and found that pin 4 was configured as an input and, as per schematics, it’s connected to pin 11 somehow.
Is this connection really needed? In order to make my PCB more compact I suppressed this connection and didn’t find any difference on functionality.
The other point is when I remove the decoder from track while lights are on, when I put it back on track I need to switch functions again to get lights back on. Wasn’t supposed to retain the functions? I saw somewhere in this forum this decoder have last state retain functionality. Mine doesn’t.
My version is 2.19 with a minor change to work with all long addresses. (Suppressed bit 3 check)
Regards from Brazil.
Thank you!

[Paul Harman]

Hi Flavio

The pin 4-11 (or 4-5) link is to tell the firmware to take the DCC input from the comparator on pins 12 and 13 (or 6 and 7) rather than pin 4 alone. This functionality is not available on some versions of the firmware where input is taken from 12 and 13 (or 6 and 7) regardless of the link being fitted. If you are using a version of the firmware that works without the link there is no need to have it unless you may be fitting an older version of the firmware. this functionality was removed to make room for more useful features.

Accessory decoders have last state retention, but mobile decoders (motor and function) do not as they expect speed and function packets to be repeated contunuously, you may need to enable this functionality on your command station if it has been switched off as it is often optional for higher function numbers.

[flavio]

Hello Paul,

Thank you for your answer.
It seems that my command station (Gaugemaster Prodigy Advanced 2) doesn’t have a continuous functions broadcast feature. In this case, my workaround was to put an 1F supercap on 5V line to keep lights on during momentary interruptions on tracks.
The problem of using a keep alive thing on this decoder is that the firmware is always changing itself to DC mode, which makes the decoder to stop reacting to DCC until capacitor goes flat.
I tried to change CV29 to prevents this, but it causes the decoder to stop responding to its own address.
The solution was change the code to do not enter to DC analog mode at all.
Now the decoder is performing just like I would like to.