Wi-Fi Data-Logger

sunworksco · October 12, 2010, 1:18am

Is there a data-logger that can be plugged into the Pololu Jrk 12v12 USB Motor Controller and another device that can Wi-Fi live-view data to my cell phone or pc laptop? I need motor and battery data and would like to download data memory from a card , too.
I have been looking at this Wi-Fi data-logger ESC/BEC at raczing.com

Regards,
John

DavidEGrayson · October 12, 2010, 4:28am

Have you seen the data loggers we sell? They don’t have Wi-Fi unfortunately, but you could use them to monitor motor activity or battery level using the analog channels (voltage divider circuit and maybe an RC filter would be required though).

https://www.pololu.com/catalog/product/1622
https://www.pololu.com/catalog/product/1623

–David

sunworksco · October 12, 2010, 9:18pm

Is the Logomatic v2 Serial SD Datalogger capable of sampling the voltage,torque and temperature of the 6-12volt rc sail-winch motor,2-sevo motor voltages and LiFe 13.2volt battery pack ?
The RX receiver is a Sombra Labs RF 8 channel.I’m not understanding this :
Note: Even though this board has 5V-tolerant inputs, it cannot measure voltages above 3.3 V. These voltages will be logged as 3.3 V.
Do you have a schematic drawing with detailed instructions how to connect the sensor wiring,etc.?
How is the Logomatic v2 Serial SD data-logger connected to the Pololu Jrk 12v12 USB Motor Controller that I am using for the sail-winch unit motor control ?
Regards,
John
Sombra Labs Instructions.pdf (186 KB)

DavidEGrayson · October 13, 2010, 4:44pm

I don’t have a detailed schematic or plan of how to do this because I’ve never done this before, and it’s possible that no one has. That shouldn’t deter you though, because the jrk and the Logomatic are both well documented. The Logomatic v2 Serial SD Datalogger can log 8 analog channels, so if you can convert all the quantities you want to measure in to analog voltages between 0 and 3.3V, the logomatic can log those quantities for you.

Here are some ideas on how to convert the desired quantities in to analog voltages:

To measure the voltage of a battery, use a voltage divider to get the voltage under 3.3V (the output of that voltage divider can go to an analog input on the data logger).
To measure the voltage across a motor, use a voltage divider to get the voltage under 3.3V and put RC filters on both of the leads to smooth out the PWM signal. This requires two analog channels per motor if the motor is driven in both directions.
I don’t know how you would measure torque of a motor, but you should be able to measure the current going through it. If the motor in question is driven by a jrk, you can tap in to the jrk’s built-in current sensing feature; just a solder a wire to the jrk in the right place and that would give you an analog output that represents the current. I can give you more info if you want to do this.

Do you have a programmable microcontroller available? Because you can get lots of information from the jrk using the variable reading commands and use the serial logging feature of the Logomatic to record that information. That would make your wiring simpler, but would require programming.

–David

sunworksco · October 13, 2010, 11:25pm

Thanks,David.
I am planning to use the Pololu Jrk 12v12 USB Motor Controller to operate the Mabuchi RE-360 6-15volt/0.77amp dc motor driven sail-winch with a digital 5K potentiometer on the final geared output on the sail sheet arm.The JRK will be connected to the RC Sombra Labs Synthesized 75Mhz receiver.See attached image of winch.
It may be easier to use this wire-less data-logger : sm-modellbau.de/shop/

Regards,
John