Changes by last author:
Changed:
| We assumed it is 5V or "12V", and 0V when off. |
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The assumption was : between 4.5V and 15V when AC active, and appr. 0V when off
* correct ! |
| 68k series with the 100k (in heatshrink coming from mot55/pin41) makes the voltage dividor ratio: |
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---- Voltage divider options (47..68k resistor in series with the "upper" 100k 0805 SMD onboard) 68k series with the 100k (in heatshrink coming from mot55/pin41) makes the voltage divider ratio: |
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* V=[5, 12, 16]
* V ./ div = 1.54 3.70 4.94 |
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* V=[5, 10, 12, 16]
* V ./ Vdiv = 1.54 3.08 3.70 4.94 So dividing 5V, 10V, 12V and 16V to => 1.54V, 3.08V 3.7V and 4.94V respectively (activation threshold is normally around 0.9 .. 1V). So it should clearly detect on and off condition. (and apparently it does, A/C idle up function became popular). Alternatively 47k series with the 100k * Vdiv=1+147/75 ( = 2.96 ) * V=[5, 10, 12, 16] * V ./ Vdiv = 1.69 3.38V 4.05 5.41 ---- Actual measurements - Voltage in view gauges / raw ADC ( mch3 ) when A/C clutch is on and off |
| So dividing 5, 12 and 16V to => 1.54V, 3.7V and 4.94V respectively (activation threshold is normally around 0.9 .. 1V). So it should clearly detect on and off condition. (and apparently it does, A/C idle up function became popular). |
| mswanson: going from memory on my workbench, I had 3.3V when active, and 0v when inactive. => perfectly matches the 47k series resistor (with the 100k SMD on PCB) voltage divider above. |
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Please edit:
What raw voltage do you see in view gauges / raw ADC ( mch3 ) when A/C clutch is on and off ? |
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Worked with an inverted' control strategy on the activation channel in the 1.2.38 firmware settings for idle control AC activation
When measuring the voltage on the car the pin seems to put out somewhere around 10V (lower than VBATT of 12-14V). I think this voltage is actually coming from the a/c control head, so its probably regulated down for some reason in the OEM application. |
| Thanks for your measurements and notes. |
| mswanson: going from memory on my workbench, I had 3.3v when active, and 0v when inactive. this worked with an 'inverted' control strategy on the activation channel in the 1.2.38 firmware settings for idle control AC activation. when measuring the voltage on the car the pin seems to put out somewhere around 10v as opposed to operating voltage of 12-14v. I think this voltage is actually coming from the a/c control head, so its probably regulated down for some reason in the OEM application. |