24 MHz M8C core with on-chip analog — the PSoC1 mixed-signal MCU
The Cypress CY8C27543-24AXI is an 8-bit PSoC1 microcontroller from the CY8C27xxx family, built around the M8C core running at 24 MHz.
16 KB Flash, 256 x 8 RAM — sizing the firmware and data footprint
With 16 KB of Flash and 256 bytes of RAM, this part targets firmware images that fit a modest control loop, configuration tables, and a small state machine. The 256 x 8 RAM is tight for buffering — a UART receive line at 115200 baud with a 64-byte ring buffer leaves 192 bytes for stack and variables. If your application needs a larger lookup table or a multi-packet serial protocol, the CY8C29566-24AXIT sibling (same 24 MHz M8C core, same 40 I/O, same package footprint) ups the Flash to 32 KB and the RAM to 2 KB, which buys headroom for more complex firmware without changing the board layout.