Renesas M34280E1GP

Overview

M34280E1GP from Renesas Electronics is a 4-bit single-chip CMOS microcomputer with 1024-word × 9-bit mask ROM and 32-word × 4-bit RAM, designed specifically for infrared remote control transmitters. It integrates a programmable 8-bit timer with auto-reload, carrier wave output on port CARR, key-on wakeup across 8 pins (D7, E0–E2, G0–G3), and operates from 1.8 V to 3.6 V supply voltage.

For engineers reviewing the M34280E1GP datasheet, M34280E1GP pinout, M34280E1GP application, or M34280E1GP equivalent, this device supports infrared carrier generation at f(XIN)/4, f(XIN)/8, f(XIN)/12, f(XIN)/64, f(XIN)/96, or fixed-H output, features ceramic resonator-based oscillation, and delivers 8.0 µs minimum instruction execution time at 4.0 MHz system clock.

Technical Context

The M34280E1GP implements a 4-bit ALU with registers A (4-bit), B (4-bit), D (3-bit), E (8-bit), and stack register SK (4-level). Its system clock derives from an external ceramic resonator connected between XIN and XOUT, with internal feedback resistor; instruction clock is STCK/4, and machine cycle equals one instruction clock cycle.

Timer 1 is an 8-bit binary down counter with reload register R1, selectable count source (CARRY signal or WDT bit 5), and configurable auto-control of carrier wave output via V1 register bits V12–V10. The device supports subroutine nesting up to 4 levels, though only 3 are usable when TABP p instruction is executed due to shared stack usage.

Key Specifications

Pinout & Package

Package: 20-pin plastic SOP (20P2N-A) - surface-mount compatible with standard IR remote PCB layouts and reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit IR microcontroller applications.

Compared with M34280M1GP, M34280E1GP offers identical hardware compatibility but enables customer-defined mask ROM programming, while uPD78F0503GC-GAD-AX provides flash flexibility at the cost of higher BOM, larger footprint, and increased design complexity for simple IR transmitters.

Availability

M34280E1GP is available at Aetrix Electronics and suitable for infrared remote control transmitters, consumer electronics keypads, and battery-powered wireless command modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for M34280E1GP includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, and power solutions for automotive, industrial, and consumer markets.

The 4280 Group - including M34280E1GP - was engineered exclusively for cost-sensitive, ultra-low-power infrared remote control transmitters, emphasizing integrated carrier generation, key-scan efficiency, and minimal external component count.

FAQ

What is the maximum operating frequency of the M34280E1GP system clock?

The M34280E1GP system clock is derived from the external ceramic resonator connected to XIN/XOUT. Its maximum rated system clock frequency is f(XIN)/8, and with a 4.0 MHz resonator, this yields 500 kHz. The device is characterized for reliable operation up to 4.0 MHz resonator input, corresponding to 500 kHz system clock - exceeding this may cause timing violations in instruction execution or timer underflow behavior. Always verify timing margins using the M34280E1GP datasheet's AC characteristics table.

Does the M34280E1GP support in-circuit programming or firmware updates?

No, the M34280E1GP uses mask ROM, which is programmed during wafer fabrication and cannot be altered post-manufacture. Firmware is permanently fixed at production; changes require a new mask revision and re-spin. This makes M34280E1GP ideal for high-volume, stable-design applications like TV remotes where protocol and key mapping remain unchanged over product lifetime. For field-upgradable designs, consider Renesas' flash-based 78K or RL78 families instead of M34280E1GP.

How many key inputs can the M34280E1GP scan simultaneously in an 8×7 matrix?

The M34280E1GP supports full 8×7 key matrix scanning using ports D (7 outputs), D7 (1 I/O), E0–E2 (3 inputs), and G0–G3 (4 inputs), totaling 8 row and 7 column lines. Its key-on wakeup function activates on any of the 8 designated pins (D7, E0–E2, G0–G3), enabling immediate wake from low-power mode upon key press. The firmware must implement sequential row activation and column readback - no hardware key scanner is integrated, but the I/O configuration and wakeup logic minimize CPU overhead during idle periods for M34280E1GP-based remotes.

What is the purpose of the CARR pin on the M34280E1GP, and how is its output frequency selected?

The CARR pin on the M34280E1GP is a dedicated CMOS output for infrared carrier wave generation. Its frequency is selected via software-controlled register bits (V12–V10 in timer control register V1) and supports seven options: f(XIN), f(XIN)/4, f(XIN)/8, f(XIN)/12, f(XIN)/64, f(XIN)/96, or fixed-H level. Selection is independent of Timer 1 operation unless auto-control mode is enabled. This allows precise, jitter-free carrier output synchronized to the internal clock - critical for reliable IR receiver detection - without consuming CPU cycles or requiring external oscillator circuitry in M34280E1GP designs.

Can unused pins on the M34280E1GP be left floating, or do they require specific termination?

Unused pins on the M34280E1GP must not be left floating. Per the official Renesas documentation, D0–D7 should be either open-circuited *after* setting their output latches to "1", or tied to VDD; E0/E1 must have pull-down transistors disabled in software before opening or connecting to VDD; E2 and G0–G3 should be open-circuited *after* setting latches to "0" or tied to VSS. Floating pins risk undefined logic states, excess supply current, noise-induced resets, or latch-up. Always follow the M34280E1GP's "CONNECTIONS OF UNUSED PINS" section - proper termination is mandatory for stable operation in production remotes.