8 MHz HC08 core with USB — the parametric anchor
The NXP MCHC908JW32FAE is an 8-bit HC08 microcontroller clocked at 8 MHz, with 32 KB of on-chip Flash program memory and 1 KB of RAM — enough code space for a USB HID class driver plus the application loop, with RAM headroom for a 512-byte buffer and stack.
USB and SPI — the connectivity that defines this variant
The MCHC908JW32FAE integrates a USB peripheral alongside an SPI port — unusual for the HC08 family, where most parts carry only SCI or no serial bus. On-chip peripherals include an LED driver, low-voltage detect (LVD), power-on reset (POR), and PWM — the LED driver saves an external transistor for indicator lights, and the LVD protects Flash writes during brownout without a supervisor IC. 29 I/O lines in a 48-LQFP package give good pin utilization — only 19 pins are consumed by power, ground, and the oscillator, leaving the rest for the application.