Great to hear that you solved it. My full name is "Karl Kristian Dyrholm Torp". Good luck with your project
It could be that you have connected In+ and In- on INA219 backwards. That would give a negative current. Great idea to add logging :)
Sounds good. No problem
I think you are missing the file FlashMem.h. It needs to be is the same folder as Tiny-VA-Meter.ino
Good Job! I’m working on something simular myself. Same screen but using a arduino M0+. Great inspiration!
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Thanks! Yes the TTP223 is very sensitive and works through most materials. They can even sense you finger a few mm before you touch it - thats why it works through the case. So it is not using the case as a conductor. I am also using standart PLA and I have also used it through wood and aluminium.
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Cool project! I can see that a lot of effort went into completing that!
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It should not be hard to modigt the code to show A instead of mA. The limit of the standard resistor is 3.2 A for the sensor. But by replacing it with a smaller resistor you can measure larger current - but with smaller resolution.
Nice project. Thanks for sharing.
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Yep :D I'm no expert on delta-sigma ADC converters. Since the gain is selectable on my meter I simply choose what suits the load I'm measuring. With the display it doesn't make sense to update faster that every 100 ms - so I can even use the 128 sample averaging if I want to. I would love to make som logging or displaying a graph with a faster sampling rate - but I'm getting low on flash :( So I think I'll end up making a new device based on an ARM processor with a touch screen.I can see your problem with the 1 ohm resistor. I have just received some 1 ohms that I'm planning to mount in a second meter. That way I can just pick the one that suits the load. I have all the spare parts laying around any way.But I also have a INA226 that I haven't tested out yet. It has a 16 bit ADC with 2.5 u…
Yep :D I'm no expert on delta-sigma ADC converters. Since the gain is selectable on my meter I simply choose what suits the load I'm measuring. With the display it doesn't make sense to update faster that every 100 ms - so I can even use the 128 sample averaging if I want to. I would love to make som logging or displaying a graph with a faster sampling rate - but I'm getting low on flash :( So I think I'll end up making a new device based on an ARM processor with a touch screen.I can see your problem with the 1 ohm resistor. I have just received some 1 ohms that I'm planning to mount in a second meter. That way I can just pick the one that suits the load. I have all the spare parts laying around any way.But I also have a INA226 that I haven't tested out yet. It has a 16 bit ADC with 2.5 uV resolution the the shunt and 1.25 mV on the bus. That might be good enough for an all-in-one solution.
So I have been updating the software over the last days to allow for full gain and average setting through the menu. So I will just share my findings with you. I found out that the resolution is fixed to 10uV (at 12bit) for the shunt voltage and 4mV for bus voltage. The gain will not change that. But gain will help reduce noice in the low ranges. Averaging does also work and is very helpfull when measuring fluctuating loads like motors.
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Thank you! That's much appreciated!
Cool! No problem. I used that screen on my prototype but later went with the 128x64 to have more information on the screen. You can use the same driver but need to configure it for the smaller screen. On my github you can see that I started out with the 128x32 screen. So you can use that as a guide for the changes. You will of cause have to adjust fonts or what is display on the menus that has 4 lines. There is not Room for that on the small screen
I have just tested with a fan myself and I'm seeing the same results. It is because of the fan motor. So you have connected everything correctly :) I am able to get stable readings by using the sensors build in averaging. So I will surely add that as a setting! But Adafruit has unfortunately not added control of this in their standard driver - So I'll have to make my own modifications. I'll add everything to Git when I have the time.
In case you want to understand better I measured the voltage of the shunt resistor with my oscilloscope. I took one reading of the FAN and one reading of an Arduino with a TFT screen on. Both around 70 mA. But as you can see the FAN is pulsing the current draw. While the arduino is more steady in the current draw. So the INA219 is actually telling the truth - the current is changing constantly. We are just used to see the averaged result from multimeters like your own.
Awesome! Motor loads can be a bit tricky to measure on since they also kan make small current spikes! I really should add the option to average readings in the settings menu. Thanks for bringing that to my attention 😉
Ok. Connections looks good. The current on a fan can change if the airflow is restricted or the motors loads changes. If you have a normal multimeter you should try to verify if the current reading is correct. You can also try to change the refresh rate to 100 ms to see if the current readings are “jumping all over the place” or if the motor is “pulsing” the current.
I haven't really done much with averaging but I might add that to the settings menu. No need to go down in resolution with a numeric display - but it would be really cool to be able to sample for a short period at a very high sampling rate and then display a graph. Really useful for motoring sleep cycles on a device. I'll be adding that to my todo list. For gain I have only used 1 or 8. But now you mention it I also don't see any difference. I get changes of 0.1 mA with /8 gain and that should only be possible with gain 1. I'll have to dig further into the adafruit driver for that. Might end up making my own
Glad you like it. Seems to be working for the most part. Looks a bit like you connected positive power to vin- on the INA. But not sure It’s a bit hard to see behind the connector. Otherwise. What load are you testing with?
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Awesome! Share a picture when you're done!
I like the idea of having multiple ranges with the INA3221. It can solve some of the drawbacks. I do know the sensor as I have used it in a logger for discharging test on small coin cell batteries. I used the 3 channels for running 3 tests at once and added a relay for cutoff to prevent over discharging of LIR batteries. This one is controlled by PC software but I might do a standalone version with touch screen and SD card for logging. Anyways. Looking forward to see if you can make something that is smaller than the Tiny meter 😀
Tiny V/A Meter With INA219
Tiny V/A Meter With INA219View Instructable »