MSP430F5324IRGCR

The MSP430F5324 is a member of TI’s MSP430F532x family of ultra-low-power 16-bit mixed-signal microcontrollers. The ‘5324’ variant provides 64-KB Flash, 6-KB SRAM, and 47 I/O pins in a 64-pin VQFN package, positioned as a mid-range device between the smaller 28-pin and larger 80-pin family members.

The MSP430 architecture is optimized for low-power operation through a combination of flexible clock management, multiple low-power modes, and an integrated LDO. The unified clock system includes a digitally controlled oscillator (DCO) for fast wake-up (3.5 µs from standby), a FLL for frequency stabilization, a 32-kHz crystal oscillator (XT1) for RTC, and a high-frequency crystal oscillator (XT2) up to 32 MHz. The on-chip LDO regulates the core supply, allowing the device to run from a single 1.8-V to 3.6-V supply.

The five low-power modes are the hallmark of the MSP430. Active mode draws 290 µA/MHz from Flash (150 µA/MHz from RAM). LPM3 (standby with RTC, WDT, and supply supervisor active) draws only 1.9 µA at 2.2 V. LPM4 (off mode with RAM retention and supply supervisor) draws 1.1 µA. LPM4.5 (shutdown with no RAM retention) draws just 0.18 µA — approaching the self-discharge rate of a coin cell battery.

The two USCI modules each support dual-protocol operation: USCI_A provides UART (with auto-baud detection) and SPI, while USCI_B provides I2C and SPI. This allows simultaneous UART + I2C, or SPI + I2C, or any combination. The 12-bit ADC includes an internal reference, sample-and-hold, and auto-scan for sequential channel sampling without CPU intervention.

The hardware multiplier supports 32-bit operations (32×32 → 64-bit result) in a single instruction cycle, accelerating DSP-like algorithms. The 3-channel DMA offloads memory transfers from the CPU, enabling ADC-to-RAM or UART-to-RAM transfers with zero CPU overhead.

Typical applications include battery-powered data loggers, wireless sensor nodes, portable medical instruments, and smart metering systems where ultra-low quiescent current and fast wake-up are essential for extending battery life.

**MSP430 CPU Core:** The MSP430 uses a 16-bit RISC architecture with 16-bit registers and a constant generator for efficient instruction encoding. The 27 core instructions handle most operations; additional emulated instructions provide convenience. The Von Neumann architecture uses a single address space for Flash, SRAM, and peripherals. The CPU runs at up to 25 MHz with single-cycle register-to-register operations.

**Unified Clock System (UCS):** The UCS manages four clock sources: XT1 (32-kHz crystal), XT2 (high-frequency crystal up to 32 MHz), DCO (digitally controlled oscillator, fast start), and VLO (low-frequency internal, 10 kHz typical). The FLL multiplies the 32-kHz reference to generate a stable MCLK and SMCLK. The DCO starts in microseconds, enabling the 3.5-µs wake-up from LPM3.

**Low-Power Modes:** Five low-power modes trade off functionality vs. power. LPM0 keeps SMCLK running (timer-based events). LPM3 keeps only ACLK (32 kHz) and RTC active (periodic wake-up). LPM4 disables all clocks but retains SRAM (interrupt wake-up). LPM4.5 disables the LDO entirely, losing SRAM content but achieving 0.18 µA (reset wakeup). The key design principle: spend most time in deep sleep, wake briefly to take measurements, then return to sleep.

**USCI Communication:** Each USCI module uses a shared shift register with separate baud-rate generators for UART and I2C/SPI modes. Switching between protocols requires reconfiguration but not a hardware change. The UART supports auto-baud detection for unknown baud rates. I2C supports master/slave with multi-master arbitration and clock stretching.