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  #21  
Old 16-01-18, 08:06
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From testing last night, the pi appears to be capable of sampling four ADC channels at 40hz (160 samples per second) , at the same time that it receives and processes the NMEA sentences at 10hz. The next step is to wire in the connections to the suspension pots.

I've started trying to fathom out the strings required to initiate the sim868 gprs component, so it'll be able to connect to the Internet and upload to the cloud. I've a giffgaff sim in the board so it should be straight forward once I've sussed it out.
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  #22  
Old 17-01-18, 11:09
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The GPRS component is working. It took a bit of trial and error last night getting all the Hayes AT+ codes sorted out, but essentially the giffgaff APN "giffgaff.com" is passed to the SIM868 chip, and the script then initiates the GPRS connection.

When it works, the SIM868 obtains an ip address, and at the moment, I've written the program to send an email using smtp to prove that it is alive.

Now I need to focus instead on the Python code pushing data up to the cloud over gprs, at a set frequency, so the real-time location and speed of the vehicle can be read and displayed on a phone or pc using the web browser. The phone signal strength is reported by the SIM868 chip, so we know when there is insufficient signal strength to allow the transfer to take place.

I'll start to accumulate some wiring and connectors, so I can fit a connector to the Pi box, that will allow the four suspension pots to be connected and sampled.
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  #23  
Old 17-01-18, 14:11
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great stuff Graham - I screwed a shelf to the wall the other day - not quite in your league !
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  #24  
Old 17-01-18, 16:23
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Quote:
Originally Posted by team knifedge View Post
great stuff Graham - I screwed a shelf to the wall the other day - not quite in your league !
I think there's a software developers joke in there somewhere.
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  #25  
Old Today, 17:57
bladeyboy bladeyboy is offline
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Motivated by Graham's progress, I connected up my own pi zero and GPS module and got it logging.
Compared to Graham's pi 3, the current draw should be much lower - and the whole thing weighs around 50g excluding battery.
But my ublox neo-6m GPS module is only rated at 5Hz. I can request quicker updates up to about 8Hz, but then it starts losing samples. An 18Hz module is now on order.
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  #26  
Old Today, 19:39
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Which module does the GPS at 18hz....

I've been working on an Excel interface to allow the captured data to be combined. Getting there slowly ????
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  #27  
Old Today, 20:02
bladeyboy bladeyboy is offline
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According to the u-blox documentation, the NEO-8M should do 18 Hz. We will see.

There used to be a 50Hz GPS hat for the Pi (adafruit??), which is now unavailable.
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