Tuesday, November 29, 2016

Well looks like its late again. About time we should call it a Biweekly update. Sorry about that first stuck with drivers for SX1231 and then lots of soldering on the way.

RFM69HW board, part of RFudaan project - WORKING!!
Also blogger for a change got updated recently. That's interesting, apart from blogger all other things Google have been modernized and made a lot AI.
My project to create a Golang based site generator, still needs to come out of being a paper drawing to a functional Go program. Till then I have to stay with blogger.

I had to do a lot of soldering to come up with the prototypes. Though the boards arrived 2 weeks back I think on 17th or so, it took me quite a while to chop them into pieces.
Thanks to Dangerousprototypes & Dirty PCB team for the great PCBs. Although this time around there were a bit of drill offsets all over. But my thumb rule of 20mil+ annular ring saves the day.


Lets go through the projects in progress:

1.RFM69HW Sensor Node

This one has gone a long way. Now that the RF-udaan parts have arrived things have become easier. As you can see from the above picture. I have successfully began RF evaluation for Bandwidth computation and sensitivity analysis for various data rates for the SX1231H on RFM69HW.

Here is another view of the prototype:

Top View of the RF69HW in action
In the picture you might wonder what is that Blue LED. Its actually the POWER LED on the Arduino Nano Clone that's being used here. Also another RED LED actually indicates when the packets are being transmitted.
Due to very nature of this project things got slow down. Initially I started with a very Arduino'ISH library but got stuck with size issues and making it portable. So I had to rewrite the entire library again using 'C' like system.
Now the new driver is 'Dynamic', in fact its so designed that one can actually
interface more than 2 RFM69HW boards to an Arduino !!
Spider proto for RFM69HW before the RF-Udaan boards

Hope that once I release the code, it would be of great help. Though the Lowpower labs library does a good job and hats off to the Radio Head lib ; I wanted some thing that can be portable beyond Arduino. Hence I have write it again. Well hope that most of you would agree rewriting is a bit of a learning trip isn't it. Still a long way from complete, RX is having issues that needs attention, plus there is nothing to do a BIT RATE ERROR (BER) test. Right now I have strapped together an array of '0x55' which kind of simulates an BER. If any one can suggest how to do this with SX1231H on the RFM69HW it would be of great help.
Boatloads of RFM69HW !!
Also, got some RFM69HW for more prototypes to come.

Sorry to all my blog readers, I could not post the details of my pondering with SX1231H but I assure you its in my long-term to-do list for this blog.

2. RF-Udaan Project


Well as you have already seen above, the board works. It was a very pleasant and fulfilling experience to see your own board work. May be I have had that over and over again but
still that feeling of joy & elation - looking at the first LED blink never goes away.

Here is a closer look at the PCBs from DirtyPCB service:
Top side of RF-Udaan PCB
Bottom Side of RF-Udaan PCB
Also I got all the Dorji DRF1276G modules just before receiving these PCBs:
A few parts from Dorji including DRF1276G LoRa module
The antenna at 868MHz for LoRa is very essential as my wire antenna technique that I discussed earlier is only a cheap jugaad measure(hack). These antennas are 2dBi so should be good for the 20-18dBm gain I can generate from DRF1276G. But still there is a hidden problem in that. The DRF1276G needs some special DIO selection to control the RF power output. I have no clue how that needs to be done. I am in touch with the Dorji's tech team for clarifying regarding this.

Here are pictures of the Base board with soldering and component population completed:

It has an DHT22 and an LDR on-board to provide sensing of temperature, humidity and light. The Pro Mini acts as the brain. And the breakout area to the side gives way for connecting either the DRF1276G or RFM69HW boards vertically.

3. Static Site generator using golang

Not much of progress on this one, as lots of Soldering and no GO code makes a sleepy developer.

4. SIM900 Relay

This one got completed and I published one update to the Arduino library on github. Hope that the library creator accepts my modification request. The exact purpose of this project was very simply to control GPIOs and read ADC along with a few inputs. All could be achieved in 2 nights thanks to the GSM-GPRS-GPS-Shield library.


Hope that you like the projects I have been presenting. Do leave your feedback and comments about the work that's going one in my labs.

That's all folks, hope to see you next time.

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