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ianbartie · 06-01-2011, 05:15 AM

I have made the change to line 1755, put in a 68 ohm resistor & have done some experimenting.
I have tried various PWM_MAX values between to 100 & 125 range to see what happens.

The car measures +0.030mV @ 71 ohms = empty & +0.70mV @ 283 ohms = full between the sender wire & car earth. The sender wire by itself measures 106mV to earth.

So far, I haven't been able to get the needle to move via the PWM yet but it will move with a variable resistor between the sender wire & earth.

By my reckoning, the PWM should be about 38% for full & about 80% for empty. That equates to a PWM_MAX of 0x61.

Reading some stuff, it seems like I may need a low pass filter. That may give a signal that the computer likes better. I could also try a digital pot perhaps.

06-01-2011, 05:15 AM	#275 (permalink)
ianbartie VW Polo EV Join Date: Aug 2009 Location: Port Macquarie Posts: 69 Thanks: 1 Thanked 10 Times in 9 Posts	Fuel Gauge I have made the change to line 1755, put in a 68 ohm resistor & have done some experimenting. I have tried various PWM_MAX values between to 100 & 125 range to see what happens. The car measures +0.030mV @ 71 ohms = empty & +0.70mV @ 283 ohms = full between the sender wire & car earth. The sender wire by itself measures 106mV to earth. So far, I haven't been able to get the needle to move via the PWM yet but it will move with a variable resistor between the sender wire & earth. By my reckoning, the PWM should be about 38% for full & about 80% for empty. That equates to a PWM_MAX of 0x61. Reading some stuff, it seems like I may need a low pass filter. That may give a signal that the computer likes better. I could also try a digital pot perhaps. __________________ Electric VW Polo Last edited by ianbartie; 06-01-2011 at 08:21 AM..