Automated laboratory experimentation is increasingly dependent on synchronized operation of a variety of hardware devices according to arbitrarily complex user-defined sequences, but there is a lack of vendor-neutral options for systems capable of producing these control signals. Custom electronic circuits with hard-wired logic lack the flexibility for use across different experiments without requiring significant modification each time. Using fully featured computers brings along the unnecessary complexity of running a complete multitasking operating system with a scheduler not suited to real-time applications. In both methods, the underlying sequence is obscured, either hidden in circuitry or extra layers of abstraction to communicate with the operating system. We present, CtrlAer, an embedded domain-specific language for describing activation signals on a synchronized parallel timeline via a simple syntax containing only a handful of primitives. Embedded within MicroPython, CtrlAer programs are directly executable on the widely available and inexpensive Raspberry Pi RP2040/RP2350 microcontrollers and their wide ecosystem of open hardware development boards. They can generate arbitrarily complex finite or infinite signal sequences on up to 16 synchronized parallel channels at up to 12.5 MHz (15 MHz on the Pico 2), scaling to the needs of scientific experiments in a variety of disciplines.