Architecture

The hardware is a Digital Signal Processor for SPM, a core component of a SPM electronics that is performing the following operations:

• Generating the x,y positions for the scan and providing them to the digital or analog piezo amplifier (which is not part of the presented  hardware)
• Maintaining feedback loop between probe and sample, e.g. keeping the probe-sample distance constant
• Driving AC signals and performing lock-in detection for advanced SPM regimes
• Communicating with user interface to the microscope (which is not part of the presented hardware) to control the experiment
• Running Lua scripts received via the communication, for performing autonomous scanning

The DSP consists internally of two independent parts described below: a feedback loop module that is implemented in the Red Pitaya (RP) single board computer, a data acquisition and generation framework that is formed by two electronics boards connected to RP via SPI interface and includes various 16 to 20 bit AD and DA controllers and RS232 interface. Block schema and photograph of the completed DSP (version 4) is provided in figure below.

All the functionality is controlled by a single C API. For running a Scanning Probe Microscope, a server is provided for a client-server operation, created using this API, which allows the electronics to be controlled from user written client outside of the RP (the graphical user interface to the microscope), connected to it via Ethernet.