  Radio-frequency (RF) signal generators are standard laboratory equipment and
a wide-range of open-source and commercial devices exists to address their many
applications. Nonetheless, only few expensive and proprietary solutions can be
re-configured within a wide frequency band and triggered on a micro-second
timescale. Such specifications are required for applications that use variable
radio-frequencies to generate programmed mixed signals, to control processes or
states and to precisely steer laser beams using acousto-optical devices, tasks
often needed in industrial manufacturing, atomic and molecular physics or
microscopy.
  Here we present an open-source low-cost Arduino-based control system that can
store up to millions of commands received from a computer and then perform
reliable high-speed programming of an arbitrary device under its control (DUC)
via a single- or quad-wire Serial Peripheral Interface. The software
architecture operates as a real-time state machine, making it easily extensible
and adaptable to any DUC. Each configuration change can be triggered either
externally or internally, reaching ~1 MHz rates when using a Teensy 4.1
Arduino-compatible board. Leveraging this flexible system, we developed a
programmable four-channel RF signal generator, based on an Analog Devices 9959
Evaluation board, and we demonstrated its capability and validated its
performance.
