24 MHz M8C core with on-chip analog
The CY8C27243-24PVXIT runs an 8-bit M8C core at 24 MHz — the clock ceiling is set by the internal oscillator, so no external crystal is needed for the CPU timing. The 16 KB flash and 256 x 8 RAM are the firmware budget: the 256-byte SRAM is the tight constraint for buffered I²C or SPI transactions, so a polling-driven loop with a small FIFO fits better than a DMA-heavy architecture. The 14-bit resolution on the ADC side gives about 16384 counts across the supply range (3 V to 5.25 V), so a 0.3 mV LSB at 5 V is achievable for thermocouple or strain-gauge amplification.
SSOP package and rework reality
The 0.65 mm pitch is wide enough that bridging between adjacent pins is unlikely with a clean tip and flux. Pin 1 is marked by a bevel on the package corner, visible under a 10× loupe.
Serial connectivity and peripheral set
I²C, SPI, and UART/USART are all available on-chip — the three common serial buses for sensor, display, and host communication. The 16 general-purpose I/O pins are multiplexed with these serial interfaces and the analog inputs, so the pin assignment must be planned at schematic capture to avoid conflicts between the ADC channels and the SPI chip-select lines. Built-in POR (power-on reset), PWM, and WDT peripherals handle basic housekeeping without external supervisor ICs. The internal oscillator eliminates the crystal and its load capacitors, saving two component placements and reducing the BOM count.
Active lifecycle and sourcing posture
No stock-holding claim — each order is verified against the BOM quantity before commitment.