Teensy 4.0 is the latest Teensy model, combining the fastest microcontroller and performance peripherals in a compact 1.4 by 0.7 inch form factor. It is designed for reliable operation and broad compatibility with existing Teensy projects. Key benefits performance with flexible timing ARM CortexM7 processor at 600 MHz on an iMXRT1062 chip, the fastest microcontroller available in the Teensy lineup. Overclocking support beyond 600 MHz for additional headroom. Serial baud rates, audio streaming sample rates, and timing functions such as delay() and millis() continue to work correctly as the CPU speed changes, with hardware and Teensyduino timing software coverage for dynamic clock scaling. Timing extensions like IntervalTimer and elapsedMillis remain reliable under dynamic clock changes. Power management and data retention A pushbutton connected to the On/Off pin can completely disable the 3.3V supply by holding the button for 5 seconds, then reenable with a brief press. If a coin cell is connected to VBAT, the RTC continues to track date and time while power is off. Power efficiency and performance At 600 MHz, typical current consumption is approximately 100 mA. Dynamic clock scaling supported to balance performance and power in batterypowered or thermally constrained applications. Form factor and compatibility Same size and shape as Teensy 3.2 (1.4 by 0.7 inches), preserving compatibility with most Teensy 3.2 pin functions. Features the same generation of peripherals and expands capabilities with the faster M7 core. Practical applications and use scenarios Realtime audio processing and streaming in compact devices where timing accuracy and speed are critical. Portable data logging with poweroff capability and timekeeping preserved via VBAT backed RTC. Robotics, sensorrich projects, or speed data acquisition where dynamic clock scaling helps optimize performance versus power consumption. Notes on capability The board emphasizes timing reliability and precise control of serial, audio, and timing functions even as clock speeds fluctuate. It is designed to provide a smooth transition between different clock speeds without introducing baud rate or timing errors. Desktop and embedded development workflows can leverage existing Teensy 3.2 pin mappings and most pin functions, while benefiting from the enhanced performance and newer peripherals of the 4.0 design.