Scaleable Multichannel Square-Wave Sequence Generator Based on the RP2040 Microcontroller

Multichannel signal generators are used in many fields of science. For example, they are used to drive ultrasonic phased arrays and usually employ FPGAs or DSPs. We present a design based on the synchronization of multiple low-cost RP2040 microcontrollers to generate digital square wave signals (PWM) with a granularity of 4 ns. Due to its modular design, the device is directly scalable to an arbitrary number of output signals. The CPU clocks are synchronized, and PIO modules are used to generate synchronized interrupts across the system. This ensures a stable phase relation across all output signals with a remaining jitter of 0.17 ns. We demonstrate the generation of chirp signals by utilizing the DMA for hardware-level data transfer. This signal generator can be utilized, for example, to control ultrasonic phased arrays and to generate arbitrary test patterns for digital circuits.