AT89C55WD-24JI

AT89C55WD-24JI is an 8‑bit, 8051‑compatible microcontroller from Atmel (now Microchip). It combines on‑chip program flash, RAM, and peripherals in a single device.
Key features
- Program memory: 8 KB on‑chip flash; data memory: 256 bytes RAM; flexible bit-addressable RAM.
- I/O: 32 I/O lines across four ports (P0–P3).
- Timers/Counter: three 16‑bit timers/counters.
- Serial: one full‑duplex UART for serial communication.
- Clock: external clock up to 24 MHz; standard 12 clocks per machine cycle.
- Peripherals: watchdog timer (WD), interrupts, on‑chip peripherals suitable for embedded control.
- Memory access/ISP: supports in‑system/factory programming; convenient firmware updates.
- Package/operating range: typically in a 40‑pin package with industrial temperature range.
What the suffix means
- WD: watchdog timer feature.
- 24: speed grade up to 24 MHz.
- JI: packaging/industrial temperature code.
Typical applications
- General embedded control, consumer electronics, automation, small motor and device controllers.

AT89C55WD-24JI is an Atmel/Microchip 8051‑family 8‑bit microcontroller. Key features:
- 8051-compatible core with on‑chip flash program memory (code storage; in‑system programmable)
- Internal RAM
- Up to about 32 bidirectional I/O lines
- Timers: two 16‑bit timers (plus standard 8051 peripherals)
- Serial interface: full‑duplex UART
- Multiple interrupt sources with programmable priority
- Built‑in watchdog timer
- On‑chip oscillator/clocking (external clock input supported)
- In‑system/programming and code‑protection options
- Wide operating voltage and temperatures (typical 4.5–5.5 V; industrial variants available)
- Low‑power modes (Idle, Power‑Down)
- Available in common packages (e.g., 40‑pin DIP and equivalents) for embedded designs
Note: exact memory sizes and some options vary by specific device variant.

- Pin count: 40 pins (DIP-40 / PLCC-40).
- Function: An 8-bit, 8051-compatible microcontroller (AT89C55 family) with on-chip 8K-byte flash, 256-byte RAM, 32 I/O lines, multiple timers, a serial port (UART), and a watchdog timer; supports in-system programming and operates with a 24 MHz clock.

Manufacturer: Atmel Corporation (now part of Microchip Technology). Atmel was a semiconductor company that designs and manufactures microcontrollers and other integrated circuits for embedded applications; Microchip Technology is the global semiconductor company that now owns and markets these products.

AT89C55WD-24JI is an 8051-based microcontroller ideal for cost‑sensitive, mid‑range embedded tasks. Common application areas include:
- Consumer electronics and home appliances (control panels, timers, displays)
- Industrial automation and small PLC‑like control (relay/motor control, sensors)
- Instrumentation and data acquisition (sensor interfacing, serial communication)
- Security and access control (keypad controllers, alarm panels)
- Automotive interior electronics (climate control, dashboards)
- Educational/prototyping and hobbyist embedded projects

44-pin LQFP (low-profile quad flat package).