High Precision AD/DA Board (Waveshare)

[Martin Probst]

Hi all,

I recently got a AD/DA Board from Waveshare (http://www.waveshare.com/wiki/High-Precision_AD/DA_Board) that I would like to use within Node-RED. I am fairly new to this but managed to quickly setup a relay board over i2c bus. However, the aforementioned AD/DA board seems to be a lot trickier and I have to clue where to start. It operates through SPI and BCM2835. C++ libraries for testing purposes work just fine.

Does anybody have an idea how I could integrate this board into Node-RED. Just a starting point and some directions would be really appreciated.

Many thanks,

Martin.

[Mark Setrem]

A good place to start would be by googling "BCM2835 node-red"  there are several tutorials that should get you through installing the BCM2835 libraries and 

demonstrate how to access data in node-red.  

If you get stuck, pop back here and I'm sure someone will be able to help, we're a friendly bunch 

[Martin Probst]

Thanks, Mark, I already ended up doing this for the last few days in a row... I got the bcm2835 libraries installed (they are also used by the C++ test programs) but most tutorials focus on DHT11 or DHT22 sensors which work differently. I would somehow need to implement SPI communication with the ADC and DAC on the board through bcm2835 and this is where I struggle. After having gone through lots of documentation it seems to me that SPI is not that well supported but I couldn't find a i2c ADC/DAC board.

Today I was looking into the Johnny-five library but didn't get all too far... :(

[Bart Butenaers]

Hi Martin,

I'm also a new member in the Node-red club, but as I understood there are a couple of ways to communicate with the pins:

• The RPI.GPIO nodes (that ship standard with Node-Red) make use of a Python libary, which doesn't support I2C or SPI yet.
• The Johnny-five nodes have a plug-in for Raspberry that makes use of the WiringPi library.  I suppose these nodes will (beside I2C) also support SPI, because wiringPI does support it.  And also the NodeJs wrapper of wiringPi does support SPI.
• I think that node-red-contrib-dht-sensor is the only Node-red node that uses the BCM2835 library.  And that only supports the DHT11/DHT22 temperature sensors over SPI.  But there are NodeJs wrappers available for that library.

From this I assume that wiringPi offers the most support for SPI and all kind of other pin-related stuff.  If the Johnny-five nodes are not sufficient, you can always use a function node to call the wiringPi functionality yourself.  

But it is only theoretical knowledge.  If you get it working, please share your solution!

Kind regards,

Bart

[Martin Probst]

Hi Bart,

thanks a lot for the overview of ways of communication! I had some trouble with the Node-Red Johnny-five plugin: Node-Red would always crash after having injected some sample code from https://github.com/nebrius/raspi-io. I am now working my way through using node.js since it offers better debugging functionalities. However, if I look at the sample C++ code used to test AD and DA functionalities, I doubt that my skills allow me to transfer this to node. We will see...

If I got something, I will keep you posted.

Regards,

Martin.

[kik...@googlemail.com]

Hi,

I don't know if this still is of interest. I'm also using this AD/DA board with node-red. At the moment I'm only interested in the ad capabilities of the board. I wrote some js code based on the c code from waveshare and this python code https://github.com/jrosenstein/PyADS1256/blob/master/pyads1256.py which is imho quite informative and very well documented. I do not have yet a working node-red node but this should be the case within the next week I hope. If everything works out as planned the code will be on npm/ flows.nodered soon. For now I managed to config the ads1256 and read from it on the with node on the command-line. I can confirm that it works well with wiringPi and also the rpio library. I ended up with rpio because I found it somewhat better documented and nicer to use (but you could easily swap one against the other without much effort).

[Piekacz Geoffrey]

Hello, do you still work with this board? I'm also trying to setup this with node-red & i'm very curious how you managed it to work.

Regards,

Geoffrey

[Levent Bal]

Hello Geofrfrey,

I think everybody can use their board. I have 5 board but I can not use too. Is there any demo, manage analog channels.

[giulio....@gmail.com]

Hello,

did you finally succeded in defining the node for the waveshare board? I have just started working with the AD part of it but I could not find your solution on npm.

Best regards,
Giulio

[Martin Probst]

HI all,

 

I managed to get it to work using some cool C++ libraries and the help of this website https://nodeaddons.com/building-an-asynchronous-c-addon-for-node-js-using-nan/

However, it’s a while ago I touched the code and it is far from being finished. It works in the console only and you need to wrap it for node-red.

You can find the code here: https://github.com/probstmartin/npm-demo-pkg

 

Good luck,

Martin.