[TangerineSDR] Git updates for Magnetometer software.

Julius Madey hillfox at fairpoint.net
Sat May 23 15:26:10 EDT 2020

As I noted yesterday, operation of the rm3100 and temperature sensor 
using 400 feet of Cat5shielded outdoor/direct burial cable using 
differential i2c signalling as designed by Scott, Dave, et al, is 
producing the same results as the successful test on 120 feet of the 
same cable a couple of weeks ago.
Differential waveforms are consistent with driving a matched terminated 
transmission line.
For curiosity's sake, the voltage supply for the remote end was 
maintained at the 3.3 volts available on the Raspberry Pi.  As expected, 
for the cable conductor resistance and current drain of the remote 
(including the transient drain of the differential driver at the remote 
end during data transfer) voltage at the remote end was slightly under 3 
volts at max current drain with a peak to peak variation that exceeded 
the 'ripple' rating of the RM3100 supply voltage which is probably 
affecting the accuracy of the RM3100.

Next step is the addition of a 3.3 Volt LDO regulator at the remote end 
with 5 volts supplied over the cable.
Jules - K2KGJ

On 5/20/2020 12:53 PM, David Witten wrote:
> All 'magnetometerists':
> I am actively updating the software on Github ( 
> https://github.com/wittend/rm3100-runMag ). I appreciate all of the 
> input I am getting.  Both Julius Madey and Dave Larsen have been 
> especially helpful. Check for updates often (if you have cloned the 
> repository, just use git pull from your projects base folder).
> The time is coming where I am going to have to ask folks to submit bug 
> fix / feature requests using the 'Issues Tracking' feature on the 
> repository ( https://github.com/wittend/rm3100-runMag/issues ) so that 
> I can avoid losing them in my email and prioritise them rationally.
> My latest commit updates the presentation of the output somewhat.  
> Important changes include more understandable messages regarding 
> missing sensors, presenting some of the values with more decimal 
> places, and more useful presentation of values entered on the command 
> line using the -P option.
> Other work continues on several fronts.  Most important (to me) at the 
> moment is synchronizing the Cycle Count (CC) values with the Gain used 
> for computing output.  Also important is constraining the CC input to 
> values that the sensor will accept.  Some other value inputs need to 
> be sanity checked.
> Please test this and give me your input and frustrations. Now is a 
> good time for me to work on this.
> Dave Witten, KD0EAG

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