STMicroelectronics ST72F321R6TC

Overview

ST72F321R6TC from STMicroelectronics is an 8-bit microcontroller featuring 32KB Flash program memory, 1024-byte 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 targets industrial motor control, sensor interface modules, and embedded power management systems.

For engineers reviewing the ST72F321R6TC datasheet, ST72F321R6TC pinout, ST72F321R6TC application, or ST72F321R6TC equivalent, this MCU delivers deterministic real-time control with nested interrupts, four low-power modes (Halt, Active-Halt, Wait, Slow), and in-application programming support-critical for field-upgradable firmware in constrained embedded designs.

Technical Context

This MCU integrates a 16MHz max CPU clock (via internal RC, crystal, or PLL ×2 multiplication), enhanced low-voltage supervisor (LVD) with interrupt capability, and auxiliary voltage detector (AVD) for analog monitoring. Its nested interrupt controller supports 14 vectors plus TRAP/RESET and Top Level Interrupt (TLI) on 64-pin variants.

The peripheral set includes a Main Clock Controller with RTC/beep/clock-out functions, configurable watchdog timer, and 48 multifunctional I/O lines (34 alternate function capable, 10 high-sink outputs). All peripherals are register-mapped and accessible via ST's standard ST7 architecture instruction set.

Key Specifications

Pinout & Package

LQFP64 14 × 14 mm package with 64 leads; thermally enhanced exposed pad (EPAD) for improved heat dissipation in continuous operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM8S003F3P6 and PIC16F1827-I/SP, the ST72F321R6TC provides superior real-time determinism via nested interrupts, dedicated TLI for fail-safe response, and integrated AVD/LVD supervision-making it uniquely suitable for industrial control where fault containment and timing predictability are non-negotiable.

Availability

ST72F321R6TC is available at Aetrix Electronics and suitable for industrial motor control, sensor interface modules, and embedded power management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ST72F321R6TC 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 automotive, industrial, and consumer markets.

The ST7 family was engineered specifically for cost-effective, deterministic 8-bit control in harsh industrial environments-emphasizing robustness, low-power operation, and integrated analog/mixed-signal peripherals.

FAQ

Does ST72F321R6TC support in-circuit programming (ICP) via its SCI interface?

Yes. The ST72F321R6TC supports In-Circuit Programming (ICP) through its SCI interface using the STVP (ST Visual Programmer) tool and compatible bootloaders. The BOOT pin must be held low during reset to enter ICP mode, and the SCI must be configured at 9600 baud with specific framing (8N1). No external high-voltage programmer is required.

What is the maximum achievable PWM frequency using the 8-bit Auto-Reload Timer (ART)?

With a 16MHz system clock and ART prescaler set to 1, the 8-bit auto-reload timer achieves a maximum PWM frequency of 62.5 kHz (16 MHz ÷ 256). Frequency resolution degrades linearly as prescaler values increase; for example, prescaler=8 yields 7.8125 kHz with 256-step duty cycle control.

Can the 10-bit ADC operate during Wait or Halt power-saving modes?

No. The ADC requires the CPU clock domain to be active and cannot sample in Halt or Wait modes. It remains functional in Active-Halt mode only if the ADC clock source (typically derived from CPU clock) is explicitly enabled via the CLK_CR register-otherwise, conversion halts upon entry to any low-power mode.

Is the TLI (Top Level Interrupt) pin electrically latched or edge-triggered?

The TLI pin is level-sensitive and internally latched. When asserted (low), it forces immediate entry into the highest-priority interrupt vector regardless of global interrupt enable status. The latch clears automatically after the corresponding ISR executes and the TLI signal returns high-no software clearing is required.