Wipers

The Wiper functionality can drive most common 4 or 5 pin common ground wiper motors, 2 speed windings or single winding. For 2 winding motors the low speed winding is not used, instead the PDM uses only the high speed winding, full power is applied for high speed and PWM with user configurable duty cycle is used to produce a low speed. A single high current output is used in Tri state mode to drive the motor and also to provide braking for repeatable park position.

PDM Inputs

Up to 5 inputs may be required depending on the level of functionality required. 

1. Park switch – This switch is required if you wish the wiper to park in a repeatable position.   Most automotive wiper motors have this functionality, some industrial and marine motors do not. The circuit generally has continuity to ground when the motor is in the park position and is a open circuit when the motor is in any other position.  This park switch must be connected to an ADIO on the PDM.

2. Mist input – This input is usually a momentary switch or button.  Activation of this input will cause the wipers to sweep the screen for the preset number of wipes, then return to park.  This input can be a physical ADIO pin, or a CAN input such as from a keypad or ECU.

3. Intermittent Input - Activation of this input will give one sweep then park, wait for the delay time, then repeat.  This will continue until the switch is turned off which will return the wipers to park.  This input can be a physical ADIO pin, or a CAN input such as from a keypad or ECU.

4. Slow input – Activation of this input will run the wipers continuously in low speed mode by pulse width, modulating the motor output at the set frequency and duty cycle.  This will continue until the switch is turned off, which will return the wipers to park.  This input can be a physical ADIO pin, or a CAN input such as from a keypad or ECU.

5. Fast Input - Activation of this input will run the wipers continuously in high speed mode, applying full battery voltage to the motor.  This will continue until the switch is turned off, which will return the wipers to park.  This input can be a physical ADIO pin, or a CAN input such as from a keypad or ECU.

Many inputs can be activated simultaneously, but the functionality of the inputs aren’t all active at once. The inputs therefore have a hierarchy for which input takes precedence. The priority of inputs is outlined in the table below in descending order.

A typical motor connection diagram – note the slow winding is not connected as well as the run contact of the park switch (if fitted).  The wiper switch could switch to ground or to 12V/5V, or could be CAN signals:

Settings Example and Explanation

Wiper Inputs

The assigned parameter/condition must be true to activate.  Note if using ADIO inputs the input pin settings have to be set up separately.  Note in the example above the conditions may be a little confusing, i.e. the Fast input condition has been set as “Fast Wipe Sw = Inactive”, this is because the switches connect to ground in this case, and with an ADIO input it is considered “Inactive” when the voltage is low (switch is shorting the input to ground) when ON. 

Slow Duty Cycle & Frequency

The PWM duty cycle and frequency that is used to drive the motor in slow mode.  Experiment with frequency to find what the motor is happy with, many will perform similarly over a wise range, some are more fussy.  The 70% and 3000Hz values in the example above gave quiet performance with similar torque and speed to the factory low speed mode with an Evo VII car.  1000Hz on the other hand produced a very noticeable whine and the motor torque was more sensitive to duty cycle.

Park Delay

This is used to add a small delay to the motor braking function after the park input becomes true.  This can be used if you want to park the wiper in a different position than the motor was designed to provide.  Set to 0 to park in the factory position.

Duration

This parameter is the wait time between intermittent wipes.

Mist Park Count

This is how many wipes are performed before returning to park when a mist is activated.

Important Caveats

The low speed coil shouldn’t be connected to the PDM.

When the wiper motor is running, especially in fast mode, the park input is only closed for a very short period of time.  For correct functionality the low threshold duration on the ADIO setup needs to be appropriate (minimal to none).  The best results were achieved with 0.00, whereas 0.10 achieved subpar results.  An indicator for the low threshold being too long is if the motor never parks when the inputs are off.

If the motor doesn’t park in the right place (or not at all) even though the input correctly detects the park switch, check that the output connected to the wiper motor has a Duty Min below 0 (-100 will stop the motor as fast as possible).