DCC custom computer controller

[Chrismalyon]

I am building a custom PC contoller for my DCC layout based on the design and code here https://github.com/Harnesser/DCC-Controller I have it working with my locos controlling direction and speed. I am now trying to get it to control the R8216 point decoder

however I am having issues getting the binary packet built. To control a train the format of the packet is as follows B10111111, B10001000, B10000000 the first section is the address the second is the data to control the train and the last is the error checking.

No matter what i try I cannot get the correct format for the point decoder.

[Gregd99]

Chris,
can you clarify who your system is configured?

I think that you have an elite connected to an arduino and then to a pc. is this right?

is the xBF, x88, x80 above being sent to the elite on the USB port? I do not recognize that message

form the xpressnet spec.

[Gregd99]

having read the web site a little it seems that the packets you refer to are dcc packets.... but I can't match them up with a spec either.....

from the look of the circuit on the web there is NO short circuit protection. this is fine for experimenting

but will be expensive eventually.

[Phil_Spiegel.]

The most likely 'problem' is that the 'address' you are sending does not match the address set on the accessory decoder 8-) This is because there CAN be a difference between the 'User Friendly' number as seen on the controller, and the 'actual data' value

sent on the dcc track bus. This is primarily because SOME people start counting from '0', and others from '1', and when combined with the 'grouping' into 8 ports (4 output pairs) 'assumed' in the nmra documentation, you may find yourself addressing somewhere

either 4 above or below where you expect. This situation is AVOIDED in normal use when an accessory decoder uses the 'Learn' method of programming its number, but when you use the CV1= method (or CV513=) you need to know whether CV1 started from '0' or '1'

for outputs 1-4 ... so try changing your binary address value up or down by 4 (which is 8 ports) and see if it suddenly comes into life.

[Gregd99]

Good point Phil...

there is definitely an "off by one" issue with points addressing on teh Elite xpressnet (to pc) interface. it is probable that this translate through to the dcc packets. NB this is off by one set of points not by one decoder address.



Play around with addresses and see what happens.

still interested to see a link to the codes you are using. I couldn't match with xpressnet or nmra specs.