HI, I’m just trying to get my head around auxiliary output control for the EMU PRO. The pinout says they can be “The load can be disconnected (Hi-Z) or connected to the ground (GND).” with “ntegrated 10kΩ pull up resistor to +12V.”. If i wanted to control a device that required an input of either connected to +12V, disconnected or connected to battery ground, could these outputs be used? and how would it be done? In the software i’m only seeing on/off, PWM or frequency as options.
Now that i’ve read the pinout document a few times i think i understand. So with the output off, the pin goes to the 12v pullup and on goes to ground, there is no floating? I think my goal might be easier with a standalone double throw switch.
Correct.
Please describe what you want to achieve.
There might be a solution, but it’s impossible to provide one without the description of the problem.
I was considering using an auxiliary output as a control input for an electric power steering rack controller that has a single wire input that when connected to battery negative gives low assistance, not connected gives medium assistance and to battery positive gives high assistance. I would like to default to high assistance with the system switched on and the engine not running (assuming the car is being pushed around the workshop). I’m now thinking the best way to do this would be through a PMU and a manual switch.
Isn’t that just a PWM signal input?
Seems like it.
We might figure this out, but I would need you to check something.
Can you measure the voltage on the control input when it’s floating (not connected to anything)?
So, I currently have an Astra EHPAS pump on the car, which works, however i have always felt that it over assists. I was going to go down the path of trying to control this hydraulicly, when i found this BMW E90 rack and controller setup that seems like it would simplify things. I’m just trying to figure out the best way to control it before i invest any money into the project, so i can’t do any measurements at the moment. The more i have thought about it, the more i think it would be best done through a simple switch. Sometimes it’s easy to overcomplicate things.
A_M_779
I think for now i’ll just run wires in the harness to the area, and revisit control strategies if and when i have the system up and running. Thankyou for taking the time to look into this.
The only thing I can think of is combining the injector output from the EMU with the output from the PMU.
Injector output from the EMU is either floating or grounded.
Output from the PMU is either floating or positive.
By connecting them together and then to the control input of the pump, you can achieve three different states.
Both outputs off = Floating
EMU output on = Ground
PMU output on = Positive
Both outputs on = Short circuit !!!
There is a risk of creating a short circuit with incorrect logic.
Setting a low trip threshold in the PMU will prevent any damage even in the case of a short circuit.
Adding a series resistor to one of the outputs would solve the short circuit problem completely, but that would have to be tested to make sure the resistor is not interfering with switching the pump input.
Thanks, using all 8 injector outs. Im thinking of just using 2 outputs to switch 2 changeover relays down near the rack. The car has a Bosch LWS steering angle and speed sensor as well, so it would be interesting to try different assistance levels based on steering rate. All things that will have to be experimented with. For now, i think if i just run B+, ground and 2 EMU outputs down to the rack i should be able to make it work.