Wiring up
Wiring up the Pulse Train Hat is very simple as you can see by the connection diagrams below.
If just using the single channel PTHAT then you can only control one stepper driver. But simply plugging in the Top Hat expansion board, this will allow a total of four channels and hence control of four stepper drivers.
Please note that the diagrams are based on stepper drivers that only require 5 volts line to be taken to the driver and 0 Volt lines are switched.
If your stepper drivers have a input for – Volts as well as + Volts on each input then, link all the + Volts lines together and connect to the 5 Volts output line. Then connect each of the – Volt inputs back to the Enable, Direction and Pulse line outputs.
We have shown different connection diagrams for different drivers near the bottom of the page.
Next diagram shows closer detail of the Top Hat expansion board.
It has extra I/O ports shown and the other three channels.
In this diagram below it shows both the PTHAT Mainboard and Topboard connected together.
The Limit switch inputs are pulled high and also the Emergency stop input. So attaching limit switches that are N/O (normally open) will take the inputs down to 0 Volts when triggered.
The ADC inputs all run on 3.3 Volts and should use the connector blocks next to them for power. Do not put a higher voltage in on the ADC inputs than 3.3 Volts, as it will damage the board. Further down the page we show how to connect some pots to the ADC inputs.
The 5 Volt outputs should be used to control mosfets or relays and not used to drive a direct load.
Note the outputs are from the 7407 open collector buffer chips on board which have a 4K7 pull up resistor. So if a very small load you could supply the 5 volt line (around 2ma), but it is recommended that you use the AUX outputs to switch 0v into the circuit as shown on the diagram at the bottom of this page this way you can pull around 20-30ma
Next below shows a typical setup combination, showing the PTHAT, stepper drivers and motors.
Here are some different connection diagrams for different types of drivers .
As you can see with the UI-Robot driver, you can simply take the signal lines straight out to the driver.
The CW5045 driver is like other high current stepper drivers that have separate inputs for – Volt and + Volt lines.
In the example above we link the + Volt lines together and take to 5 Volts.
The small low cost DRV8825 stepper drivers have the same connections as the A4988 drivers. Take Reset and Sleep to 5 Volts.
Finally above we show examples of how to connect the ADC inputs and Aux 5 volt outputs.
The Limit switch inputs are pulled high and also the Emergency stop input. So attaching limit switches that are N/O (normally open) will take the inputs down to 0 Volts when triggered.
The ADC inputs all run on 3.3 Volts and should use the connector blocks next to them for power. Do not put a higher voltage in on the ADC inputs than 3.3 Volts, as it will damage the board. Further down the page we show how to connect some pots to the ADC inputs.
The 5 Volt outputs should be used to control mosfets or relays and not used to drive a direct load.
Note the outputs are from the 7407 open collector buffer chips on board which have a 4K7 pull up resistor. So if a very small load you could supply the 5 volt line (around 2ma), but it is recommended that you use the AUX outputs to switch 0v into the circuit, this way you can pull around 20-30ma
At the moment the Aux outputs are set low on start up, but on reflection this needs to be changed so they are high on start up and when the Set on/off Aux Output Command is sent that the lines switches from high-low. We will amend this in the next firmware release.
Closer look at the PCB's
PTHAT Mainboard
- Single Channel Main Board.
- JTAG Programmer.
- Set of Mounting Spacers and Bolts.
PTHAT Add on Board
- Expansion Add on Board.
- Increases the PTHAT to 4 channels.
- Extra I/O Functionality.
- Set of Mounting Spacers.
PTHAT Full Package
- Single Channel Main Board.
- Expansion Add on Board.
- Increases the PTHAT to 4 channels.
- Extra I/O Functionality.
- JTAG Programmer.
- Set of Mounting Spacers and Bolts.
- Save £10 with this Package