stokerkontrol (woody looging of data on dd-wrt)

[pso]

Hi

I write this in English because at least one of the persons who is active in the Raspberry Pi tread is not Danish. Second with all the technical word it might soon turn into a lot of english words anyway.

My project is just another version of the Raspberry Pi project. As HW I will use a wireless router with open source linux code called dd-wrt.
The task is to gather data from a Woody/Scotte controller version 6, which has an RS 232 port (I know I have to add the level voltage translator for RS232 levels). The HW I have is a Cisco Linksys E900 with an internal RS232 port. Beside logging it must also act like a router expanding one ethernet cable to 2 or 3.

I am an electronic Engineer, but some basic knowledge of linux and programming but very limited handson. I will properly not be able to complete this task without some help from more competent people.

I have done step one which is to load the standard open source dd-wrt code on router instead of the preloaded Cisco code.
I assume the code allready holds a driver for the RS232 port but I do not know for sure, I will find out.

E900 has 8 MB flash and 32 MB ram

The box must collect data and store them in RAM (assuume 16Mb free out of 32 Mb). From there the data will be polled by a PC that is not allways turned on.
I do not know the amount of data to be store by now and thereby how long time

Next step is to decide if I should use some of the stokerkontrol java code (no display of data) eller python code made for Raspberry Pi. My best guest is that I will use the Python scripts.

Please fell free to comment

[Juel]

I like this project! Some might ask why? Answer.. "becurse its posible"

The only problems I see with this solution, is logging Space.. But that could be solved, with a router that has an USB port
Another issue could be performance on the router...

But very exicting project

[motoz]

Great project!
If you don't want (or can't, I don't know how easily you can get dbus running on dd-wrt) to run all of PellMon then you can easily use just the scotteprotocol python module like this:

Kode: Vælg alt

from Scotteprotocol import Protocol
p = Protocol('/dev/ttyUSB0', 'auto')
print p.getItem('boiler_temp')

(You'll need the pyserial module installed)

By the way, it's quite possible that the internal serial port of your router has the same (0..5V?) logic levels as the woody, so then you would either have to add a level converter in both ends, or you could possible be able to skip them both.

Keep us informed of your project!

[pso]

Does anyone know how much data stokerkontrol logs pr log iteration?
The CPU is not as fast as the PI, but as long as it should not run java code to display data, that should be enough. The broadcom bcm5357 CPU is 300 MHZ

[pso]

I have read a little about dbus, as it is open source code for linux it should be possible to compile for E900, however a god question is how much ram does it use.
I have found some forum thread that says that dbus usage is depending on the application calling it.
So perhaps one of you could try an see that on your running PI while logging data with the python script, you could also see how much the python code use?

[Juel]

I can check mine later when I get home

[pso]

Perfect Thanks

[Juel]

pellmonsrv.py uses about 84MB
pellmonweb.py uses about 153MB
And my database after 2 month is about 8MB

[motoz]

How do you measure that? I honestly have no idea how to figure out precisely how much memory a process uses. Anyway it seems a bit high, I have the 256M version of the raspberry, top reports:

KiB Mem: 188872 total, 173640 used, 15232 free, 10492 buffers
KiB Swap: 102396 total, 0 used, 102396 free, 105488 cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1470 pellmonw 20 0 172m 17m 3840 S 11.8 9.7 1183:38 pellmonweb.py
25115 pellmons 20 0 100m 10m 3700 S 2.0 5.8 337:35.19 pellmonsrv.py

The size of the database is fixed when it is created, it does not grow all (since it is an RRDtool database)

[pso]

Hmmm I think python and d-bus demands too much RAM for my HW. I read that they are some kind of high level object oriented code.
I need to have RAM for Woody data and the router code, so I can only allow the added code to use very little RAM.
Now I am considering to rewrite the python script to ansi C. Which means I should just be able to extract the RS 232 protokol from the script.
Or is the protokol documented in a more readable way?
Being able to write Ansi C for embedded HW is also much more usefull for my kind of work as a HW engineer.