PZ Probe

After sucessfully connecting and mounting the PZ Probe, as well as adding the code needed in the configuration, there are some important details about how the PZ Probe works and what impacts the performance:

• The more rigid the motion system that the PZ Probe is installed on, the better it will perform. This means, lower sensitivity and probing speeds can be used. Less rigid systems are more likely to not trigger and therefore usually require higher probing speeds.
• Vibrations from the motor and Z-axis moving is the most common cause for false triggering and so it is important to drop the motor current during probing as much as possible. This will also save damaging your bed if no triggering occurs.
• A useful way to test the PZ Probe while changing settings is to lightly tap the tip of the nozzle with a small metal ruler or pen. A yellow light will appear on the PZ Probe Board if a trigger is outputted. If you don't observe this behaviour, please check the troubleshooting guide.
• It is recommended when probing the bed, to probe when the nozzle temperature 50°C below the target temperature to avoid oozing. Plastic on the nozzle flat will result in poor probing repeatability and potentially result in a No Triggering failure mode.
• Probing speed is very important. Probing too slow will result in a No Triggering failure mode. Probing too quickly will result in inconsistent and inaccurate probing. See the troubleshooting section for more details. Acclerations and Jerk also has an impact on probing.
• The output signal (Trigger) from the PZ Probe board is an active low signal. This means that when idle it is high (5V/3.3V) and then triggered, the output signal does to 0V (GND).

The Heatsink is mounted as with a normal Voron Heatsink.

The heatsink has a "wire" with a 4 pin connector coming out of the central body, this will be referred as the flat flex. 
The flat flex can then be routed through the cable channel and then connected to the PZ Probe Board.

Connect the flat flex to PZ Probe Board as in the image below. Ensure the black stiffener is facing up as in the image.

The PZ Probe Board can then be connected to the cable with the 7-pin connector as shown in the image below, To see the pinout of this connector, please see the "Pinout" tab later in the guide. 

The cable has four other connectors each with their own functions:

1. The EndStop connector - if you have an octopus board for example, this can plug straight into the endstop connector on the board.

2. UART connector - if you have a Raspberry Pi, this can be connected directly to the pin header of the Pi.
    See the tab "Configuration" > "Raspberry Pi with a Python script".
    This is an optional connector to plug in, and is only needed when configuring the preset settings.

3. UPDI Connector - This can be used to program the microcontroller using a UPDI programmer. In most cases, users will not use this connector.

4. I2C Connector - This can be used to configure the Preset settings with an alternative form of commuinication. This is the least preferred way of communication (UART is the recommended way). 

The PZ Probe Board can be mounted in 2 different ways: 

1. It can be mounted using the mounting holes by securing it with the M2 machine screws provided, in a convenient location on the printer or setup. Since the area around the mounting holes is clear, they can also be drilled to accommodate M3 screws. 

If you are mounting the PZ Probe Board to Voron, you can mount the baord on the X-carriage, using the modified 3D-printed parts:

2. Attach double-sided tape (not provided) to the back of the PZ Probe Board, then place it in a convenient location on your printer or setup.You can break off the PCB's part with the M2 mounting holes by breaking the mouse bites - this is particularly useful for placing the PCB in a small area.

Before you start using PZ Probe, make sure to do the following changes to avoid any damage to your setup:

1/ These settings have been tested on our setup, but they may vary slightly depending on your setup. Please use them as a starting point, and make sure to go through all the steps below.

2/ During probing, reduce the current as much as possible without causing a stall. A good starting point is 40%, but lowering it further, if possible, will reduce the risk of damaging your bed. We have set our probing speed to 5 mm/s.

3/ In our testing procedures, we used the Roto toolboard (pin: !roto_tb). Make sure to correctly name it, as well as the other pins, according to your setup. 

4/ Probe and check. If you experience false or no triggering, follow the steps in the troubleshooting tab.

In Config.g add the following:

Note that for G31, X and Y offset may need to be changed for your hotend. Z should be kept at 0.

You can now send commands via the command line, in a config or macro using the line below.
M118 P2 S"STATUS" L2 ; Get Status of probe
Replace STATUS with any commands from the "Commands" section.

By pressing the button on the controller, you can switch between 8 pre-configured presets. Seven of these presets are configurable via UART or I2C, while the preset"0" remains as the default and cannot be configured. These can be configured by looking at the Configurations and Commands section fo this guide.

On power up, Preset 0 is used by default. If you choose to change the preset, for example, you choose Preset 2, the PZ Probe Board will power up using Preset 2.

The table below shows the default values for each of the presets:

• Preset – Which preset setting you are in. Values shown in the table to the right of Preset are associated with the preset setting The preset that is being used can be changed easily by pressing the button on the PCB. The preset state is recovered after power cycling the PCB.
• Threshold – This sets the sensitivity of controller (smaller number is more sensitive). The threshold value directly correlates to the 12-bit ADC, so if a threshold of 10 is set, the controller waits until the ADC reads a signal that is 10 or higher to trigger. 
• Trigger direction  – This determines if the trigger is a rising-edge or a falling-edge trigger.  This will usually be a rising-edge trigger in this application as the PZ Probe provides a pulse in the positive direction when compressed. Note: This does not change the output polarity.
• Filter Active – This activates the IIR filter (1) or deactivates (0) the filter. The filter has two parameters; Centre Frequency and Bandwidth which are discussed below. This is useful to activate when noise from the heatsink fan interferes with triggering.
• Filter Centre Frequency  – This stores the value of the frequency of the noise that is to be cancelled out.
• Filter Bandwidth  – This stores the value of the range of frequency away from the centre frequency that should be cancelled out. 
• Safety Trigger Active  – This should always be set to 1 as it ensures that the controller outputs the trigger state during UART or I2C communications to reduce the chance with a collision with the bed. This can be switched off, if this behaviour isnt desired. 

There are 5 LEDs on the PZ Probe Board:

• One LED is labelled PWR and is always on when there is power connected.
• Another LED is labelled TRIG, this indicates when the PZ Probe Board is triggered (usually for ~100ms). If this LED is continously on or never comes on, see the "Troubleshooting" section.
• There are 3 LEDs on the PZ Probe Board (labelled MODE 3, 2, 1) that turn green in a binary sequence after you press the button. The figures below will guide you through the different LEDs combinations and their corresponding mode.

Connect the PZ Probe Board to the arduino board such as an Arduino Mega. This can be done by connecting some jumper cables between your Arduino and the PZ Probe extension cable:

 Arduino Mega           PZ Probe Board

• 5V --------------- PWR
• GND ------------- GND
• RX1 -------------- TX
• TX1 -------------- RX

Keep in mind that Serial1 is RX1 and TX1 and USB is on RX0, TX0

Open Arduino IDE, and then open the SerialPassthrough example.

Ensure board and port are set.

You can identify the appropriate COM in tools

Set baud rate in serial monitor to 9600, and termination to newline

If you disconnect and reconnect the PZ Probe Board while the terminal is open, a message similar to the one shown in the last image will appear. The Commands that can be used to program the PZ Probe can be found under the "Commands" section of this datasheet.

If you choose to go with this second option, you will need a USB to TTL UART Converter (Like this one here).

Make sure to get a USB to TTL UART Converter with the correct voltage: 5V/3.3V.

Ensure the board is set to some generic like a Mega or Uno and set the correct COM port for your device

Set baud rate to 9600 and termination to newline

If you disconnect and reconnect the PZ Probe Board while the terminal is open, a message similar to the one shown in the last image will appear. The Commands that can be used to program the PZ Probe can be found under the "Commands" section of this datasheet.

In this third option, you will need PuTTY. If you don't have it, you can download it here.

After you download it, make sure to select the appripriate COM Port under PuTTY Configuration and set Baud Rate to 9600.

You can identify the appropriate COM in your device manager.

Ensure that the following changes are implemented: 

• Tick "Implicit CR in every LF"
• Under "Line discipline options", choose "Force on" for both "Local echo" and "Local line editing"

If you disconnect and reconnect the PZ Probe Board while the terminal is open, a message similar to the one shown below will appear. The Commands that can be used to program the PZ Probe can be found under the "Commands" section of this datasheet.

If another terminal is used, ensure that:

• Baud Rate is 9600
• Only use \n or Line Feed to terminate messages
• Only send message when enter is pressed

Configuring the PZ Probe Board via DUET is simple.
There are only three steps:

Step 1: Connect the PZ Probe Board to the DUET via the Panel Due Connector.

Step 2: In the Config.g file or in the command line, write:
   M575 P1 B9600 S1 ;Set baud rate on panel due connector

Step 3: You can now send commands via the command line, in a config or macro using the line below.
   M118 P2 S"STATUS" L2 ; Get Status of probe
   Replace STATUS with any commands from the "Commands" section.

This method of configurating requires the UART pins (RX/TX) to be connected to the pin header of the Raspberry Pi. When doing so, ensure that the power of PZ Probe Board is connected to the 3.3V.

If you are using the Raspberry Pi on your 3D printer and PWR, GND and TRIG are connected to the printer control board, then only RX/TX have to be connected to the Raspberry Pi. The printer control board must by 3.3V to do this method.

1. Power up and login to your Raspberry Pi. If UART isn't already active, activate it in Raspi-config.

2. Within the terminal, type in:
    sudo nano /boot/cmdline.txt

3. Delete the serial console parameter, it may look something like this:
   console=serial0,115200
   Then save and exit the file.

4. Create a python script. This can be done within the terminal by typing:
   nano piezo_config_config.py
   Copy the code from below and paste it within the piezo_config.py file:

5. Save the file and exit the nano editor. 

6. In the terminal, ensure you are in the same directory as the python script and type:
   python piezo_config.py

7. The script will then ask you to enter a command. Use the Commands tab to type in a particualar command you wish to use. The script will execute the command and send any replies to the terminal. The scipt will end when there are no more messages recieved from the PZ Probe Board after 2 seconds.

In the image below, an example of communicating with the PZ Probe Board via the Raspberry Pi Terminal can be seen:

Line 1: shows the command to start the python script. 
Line 2: the scipt asks what message to send. The message is then typed in. 
Line 3-6: shows the response from the Piezo Controller confirming that the change has been made.
Line 7: shows that the script recieved no further data from the Piezo Controller, so the script was terminated.

If a command didnt't have intended result because a result like "No valid command received, please try again." was provided. Then, please try to rerun the scipt or connect/disconnect the PZ Probe Board.

The script may need to be modified if UART isn't identified as Serial0, You can use ls /dev/serial* in terminal to find the appropriate serial device.

False triggering can be the result of one or both of the following: 

• Sensitivity being set too high
• Too much noise (mechanical or electrical) from the printer

Sources of noise may come from:

• Motor vibrations
• Heatsink and/or part cooling fan(s)
• PWM signal from the heater
• Jerk/Acceleration settings that are too high for the Z-axis

We recommend the following resolutions:

• Reduce motor current during probing. Ideally, the motor current should be as low as possible without stalling the motors.
• Use the built-in filter - this can be particularly useful for noise from the fan or heater. Use "REPORT ADC" command via Arduino terminal to determine the frequency of the unwanted noise. Then, it can be filtered using the filtering settings. Refer to "Preset Settings" tab for more details.
• Decouple the fan wire away from the heater wire. 
• Reduce sensitivity by increasing the threshold value - see the SET command in the Commands section for this.

Ensure that there is a short delay (around 200ms) added between X/Y movement and beginning of probing. 

No triggering can occur when plastic buildup on the nozzle tip interferes with probing, causing bed collisions because the PZ Board didn't get triggered. 

We recommend the following resolutions:

• Make sure the black stiffener at the end of the flat flex is facing upwards. 

• Increase the probing speed - this may be particularly important for less rigid motion systems.Optimum probing speeds are between 3-7mm/sit can be pushed up to 20mm/s (only if the motor current is set as low as possible to avoid damaging the bed). 
• Increase sensitivity by decreasing threshold. Refer to "Preset Settings" under "User Guide" tab for more details about the "threshold" parameter. 
• Check extension wire continuity

Make sure there is no plastic on the nozzle tip, as this can interfere with probing. For reliable probing, clean the nozzle before printing and set the nozzle temperature to 50°C below the print temperature.