Frequently Asked Questions

Can I attach motors directly to the outputs?

No, you will certainly blow up your Pulse Train Hat!
The outputs are designed to be connected to devices that have Opto Isolated inputs such as Stepper Motor Drivers.
The motors would have a separate power supply away from the Raspberry PI and PTHAT.

What current can the outputs handle?

Each output is through a buffer chip and will allow you to draw upto 40ma. But we recommend 20-30ma max.

What voltage are the output ports?

All the output ports are 5 volts.

Can I write my own firmware?

You sure can and we even supply the PTHAT with a JTAG programmer to allow you to upload it.
We will be providing full pin out details of the STM32F411RET ARM processor that we use on the PTHAT.

What voltage are the input ports?

All input ports are 3.3 volts.
But please note that the limit switch and emergency stop ports are pulled high on the circuit to 3.3 volts. To trigger them you simply supply 0 volts.
Each limit and emergency stop ports have two pins, one is o volts and the other is the input. So simply wire your switches to these two lines.

What is the voltage and resolution of the ADC's?

The ADC’s (Analog-to-Digital Converter) are 3.3 volts and 12bit resolution.
There are 3.3v and 0v connectors next to the ADC inputs.
Raw output of the ADC is sent back with a value of between 0-4095 when a sample is requested. The ADC Vref is tied to the 3.3V supply from the Raspberry PI supply and if a little noisy minimum values could start around 25-50′ so allow for this.

Why use ASCII commands?

We decided on ASCII commands to make it easier for the end programmer.
While we agree that by using this method that we are having to send more bytes of data each time, but with the buffer option in firmware it should make up for that.

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