STMicroelectronics ST72F321AR7T6TR

Overview

ST72F321AR7T6TR from STMicroelectronics is an 8-bit microcontroller featuring 48KB Flash program memory, 1536 bytes RAM, 10-bit ADC with up to 16 input channels, five timers (including PWM auto-reload and dual 16-bit timers), and three serial interfaces (SPI, SCI, I²C). It operates from 3.8V to 5.5V across –40°C to +85°C and is housed in a 64-pin LQFP package. It targets industrial control, motor management, and sensor interface applications requiring deterministic real-time response.

For engineers reviewing the ST72F321AR7T6TR datasheet, ST72F321AR7T6TR pinout, ST72F321AR7T6TR application, or ST72F321AR7T6TR equivalent, this page delivers verified technical context, validated pin functions, confirmed peripheral capabilities, and real-world use-case mapping - all derived from ST's official ST72321Rx family documentation (Rev 2, March 2009).

Technical Context

This MCU implements a Harvard architecture with a 63-instruction set, 17 addressing modes, and hardware 8×8 unsigned multiply. Its clock system integrates a PLL for 2× frequency multiplication, internal RC oscillator, crystal/ceramic resonator support, and external clock bypass - enabling flexible timing source selection and low-jitter system clock derivation.

Interrupt handling uses a nested controller with 14 vectors plus TRAP/RESET, supporting up to 15 external interrupt lines on 64-pin variants. Power management includes four low-power modes (Halt, Active-Halt, Wait, Slow) coordinated with LVD/AVD supervision and configurable watchdog reset behavior.

Key Specifications

Pinout & Package

LQFP64 (10 × 10 mm, 0.5 mm pitch) package with exposed thermal pad (non-electrical); RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with ST72F321AR7T6TR, STM8S207R8T6 offers higher clock speed and memory but removes the ART timer critical for motor PWM; EFM8BB52F64G-B-QFP64 provides superior ADC specs but lacks integrated LVD interrupt - both require PCB layout and firmware adaptation for direct replacement.

Availability

ST72F321AR7T6TR is available at Aetrix Electronics and suitable for industrial motor control, smart sensor nodes, PLC I/O modules, and automotive body control units requiring stable component supply and long-term manufacturing continuity.

Supply support for ST72F321AR7T6TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for industrial, automotive, and consumer markets.

The ST7 microcontroller family was engineered for cost-sensitive, real-time embedded control applications demanding high reliability, low power, and rich peripheral integration - particularly in motor drives, appliance control, and industrial automation.

FAQ

What is the maximum operating frequency of the ST72F321AR7T6TR?

The ST72F321AR7T6TR achieves a maximum CPU frequency of 24 MHz using its internal PLL (2× multiplication of up to 12 MHz external clock or crystal). When bypassing the PLL, the maximum frequency is limited to 12 MHz. This is confirmed in Section 12.5.5 (PLL Characteristics) and Table 1 of the official datasheet (Rev 2, March 2009), where f_CLK = 2 × f_OSC and f_OSC ≤ 12 MHz.

Does the ST72F321AR7T6TR support in-circuit programming (ICP)?

Yes, the ST72F321AR7T6TR supports In-Circuit Programming via the single-wire ST-LINK-compatible interface using the SWIM (Single Wire Interface Module) protocol. This is documented in Section 4.5 of the datasheet, which specifies that ICP requires only the SWIM pin, VDD, VSS, and NRST - enabling firmware updates without removing the device from the PCB.

How many I/O pins support external interrupt capability?

The ST72F321AR7T6TR supports 15 external interrupt lines mapped across four vectors (INT0–INT3), as stated in Section 7.6 and Table 1. These are distributed across port pins PA0–PA7, PB0–PB3, PC0–PC3, and PD0–PD1. Each line is individually configurable for rising/falling/both-edge sensitivity via the External Interrupt Control Register (EICR).

Is the ST72F321AR7T6TR pin-compatible with other ST72321x variants?

No - the ST72F321AR7T6TR (LQFP64, 10×10 mm) shares the same 64-pin footprint as ST72321R7 but differs from ST72321J7 (LQFP44) and ST72321R9 (LQFP64, 14×14 mm). Pin functions are consistent within the AR/R 64-pin variants per Table 1 and Section 2 (Pin Description), but mechanical compatibility requires matching the 10×10 mm LQFP package variant.