Possible issue with Tab5 and UiFlow v2.3.1 - (i2c driver install error)
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So if I assume the ADC 12 bit option will give me 4,096 different points and the ADC 16 bit option will give me 65,536 different points maybe I can come up with a formula ( using the voltage - Pressure graph) of how to calculate Kpa when using ADC option for the Tube pressure... Everyone I am just thinking out loud so don't bash me too badly... LOL!
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what are RAW values you are getting from your sensor? pure analog read value?
try below
float raw = analogRead(sensorPin); // Read analog value
float Vout = raw / 4095.0 * 3.6; // Convert to voltage (assuming 3.6V reference)
float P = (Vout - 0.1) / 3.0 * 300.0 - 100.0; // Calculate pressure in kPa -
@robski Thanks for replying! With nothing connected to the Tube pressure sensor, I am getting a RAW value of 3,287 (12 bit option selected in the ADC parameter).
In regards to a 3.6V reference, where is that in the documentation?
I think we are getting close to solving this problem!
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@robski - I stumbled across this youtube video about an Arduino Pressure Sensor and was thinking about testing a version of his method for coming up with a calculation...
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with your raw value as 3287
sensor range -100 to 200
analog range 0 to 4095your calculated pressure should be around 140
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@robski - hmmm.... Well that raw value was with nothing connected to the Tube Pressor sensor. Because nothing is connected to the tube pressure sensor I would assume it would be closer to 0 Kpa... 140Kpa is a big difference from 0 Kpa... I wonder what we are missing?
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@robski I keep coming up with 140Kpa also...
We must be missing something... -
just connect voltage to sensor and measure what voltage it is giving out between output pin and ground. for 0 kPa your raw Analog value should be around 1300 i think
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@robski - I think you hit on something there! I measured the voltage between the ground and the sensor and it came to around 1.1v which according to the graph should be around 0 Kpa. (see attached photos) Something is definitely strange...
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This post is deleted! -
Also here is the formula I was using to calculate Kpa
So for 12 bit parameter, this gives a kpa resolution of 300Kpa/4096 bits or 0.0732421875 kpa/bit (73.2pa/bit)
x = ( (0.0732421875 kpa/bit * Raw Value bit) - 100Kpa)
x = ( (0.0732421875 kpa/bit * 3287 bit) - 100Kpa) = 140.7KpaFor the 16 bit parameter this gives a kpa resolution of 300Kpa/65536 bits or 0.00457763671875 kpa/bit (4.6pa/bit)
x = ( (0.00457763671875 kpa/bit * Raw Value bit) - 100Kpa)
x = ( (0.00457763671875 kpa/bit * 52600 bit) - 100Kpa) = 140.8Kpa -
@robski I sent an email to M5Stack Support about the possible issue with the Tab5 and Tube Pressure sensor BUT no response so far....
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@Kenzo
This is an ADC problem. We are fixing UiFlow2 codes. Please be patient. -
@kuriko Thanks Kuriko for responding and taking a further look into the issue! Looking forward to testing out the updated version of UiFlow with the fix!
I will now wait quietly and patiently while your team works on an ADC fix.
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@kuriko Just finished testing the latest release of UiFlow (v2.3.2 ).
The Kpa readings was better this time but the accuracy is not there yet... See attached photo.
Hopefully the next release will improve the accuracy of the Tube/Air sensor and Tab5...
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Just tested another release of UiFlow (version 2.3.3) for the Tab5... Unfortunately, I am seeing the same results that I saw with Version 2.3.2... -16Kpa without any air tubes connected to the M5Stack Air Tube sensor... Along with the i2c driver install error...
Hopefully M5Stack Team is getting close to resolving the issue... I was planning to use the Tab5 project I was working on for the M5stack Innovation contest but it looks like that will not happen due to the issues I am running into with finding an air tube sensor that will accurately work with the Tab5... Oh well... Hopefully the M5stack team will release an upgraded Air Tube sensor soon that will easily work with the Tab5... Until then, I will keep searching for a solution....
