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The MSP430 is a mixed-signal microcontroller family from Texas Instruments, first introduced on 14 February 1992.^[1] Built around a 16-bit CPU, the MSP430 was designed for low power consumption^[2] embedded applications and low cost.

Features

The MSP430 has a maximum CPU speed of 25 MHz. The current drawn in idle mode can be less than 1 μA. The MSP430 uses six different low-power modes which can disable clocks and the CPU as well as wake-up in under 1 microsecond.

The device comes in a variety of generations featuring the usual peripherals:

• Internal oscillator,
• Timer including pulse-width modulation (PWM),
• Watchdog timer,
• USART,
• Serial Peripheral Interface (SPI) bus,
• Inter-Integrated Circuit (I²C),
• Analog-to-digital converter (ADC) options:
  • 10/12/14-bit successive-approximation ADC
  • 16/24-bit delta sigma ADC
  • Internal analog comparator with digital timers
    • Can measure resistor-capacitor slope charging time^[3]
• Brownout reset circuitry.

Some less usual peripheral options include on-chip operational amplifiers (op-amp) for signal conditioning, 12-bit digital-to-analog converter (DAC), liquid crystal display (LCD) driver, hardware multiplier, USB, and direct memory access (DMA) for ADC results. Apart from some older erasable programmable read-only memory (EPROM, such as MSP430E3xx) and high volume mask ROM (MSP430Cxxx) versions, all of the devices are in-system programming enabled via Joint Test Action Group (JTAG), full four-wire or Spy-Bi-Wire), a built in bootstrapping loader (BSL) using UART such as RS-232, or USB on devices with USB support. No BSL is included in F20xx, G2xx0, G2xx1, G2xx2, or I20xx family devices.

Memory limitations

There are, however, limits that preclude its use in more complex embedded systems. The MSP430 does not have an external memory bus, so it is limited to on-chip memory, up to 512 KB flash memory and 66 KB random-access memory (RAM), which may be too small for applications needing large buffers or data tables. Also, although it has a DMA controller, it is very difficult to use it to move data off the chip due to a lack of a DMA output strobe.^[4]

MSP430 generations

Six general generations of MSP430 processors exist. In order of development, they are: '3xx generation, '1xx generation, '4xx generation, '2xx generation, '5xx generation, and '6xx generation. The digit after the generation identifies the model (generally higher model numbers are larger and more capable), the third digit identifies the amount of memory included, and the fourth, if present, identifies a minor model variant. The most common variation is a different on-chip analog-to-digital converter.

The 3xx and 1xx generations are limited to a 16-bit address space. In the later generations this was expanded to include '430X' instructions that allow a 20-bit address space. As happened with other processor architectures (e.g. the processor of the PDP-11), extending the addressing range beyond the 16-bit word size introduced some peculiarities and inefficiencies for programs larger than 64 KB.

In the following list, it helps to think of the typical 200 mA·Hr capacity of a CR2032 lithium coin cell as 200,000 μA·Hr, or 22.8 μA·year. Thus, considering only the CPU draw, such a battery could supply a 0.7 μA current draw for 32 years. (In reality, battery self-discharge would reduce this number.)

The significance of the RAM retention vs the real-time clock mode is that in real time clock mode the CPU can go to sleep with a clock running which will wake it up at a specific future time. In RAM retention mode, some external signal is required to wake it, e.g., input/output (I/O) pin signal or SPI slave receive interrupt.

MSP430x1xx series

The MSP430x1xx Series is the basic generation without an embedded LCD controller. They are generally smaller than the '3xx generation. These flash- or ROM-based ultra-low-power MCUs offer 8 MIPS, 1.8–3.6 V operation, up to 60 KB flash, and a wide range of analog and digital peripherals.

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 0.7 μA real-time clock mode
  • 200 μA / MIPS active
  • Features fast wake-up from standby mode in less than 6 μs.

• Device parameters
  • Flash options: 1–60 KB
  • ROM options: 1–16 KB
  • RAM: 128 B–10 KB
  • GPIO options: 14, 22, 48 pins
  • ADC options: Slope, 10 & 12-bit SAR
  • Other integrated peripherals: 12-bit DAC, up to 2 16-bit timers, watchdog timer, brown-out reset, SVS, USART module (UART, SPI), DMA, 16×16 multiplier, Comparator_A, temperature sensor

MSP430F2xx series

The MSP430F2xx Series are similar to the '1xx generation, but operate at even lower power, support up to 16 MHz operation, and have a more accurate (±2%) on-chip clock that makes it easier to operate without an external crystal. These flash-based ultra-low power devices offer 1.8–3.6 V operation. Includes the very-low power oscillator (VLO), internal pull-up/pull-down resistors, and low-pin count options.

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 0.3 μA standby mode (VLO)
  • 0.7 μA real-time clock mode
  • 220 μA / MIPS active
  • Feature ultra-fast wake-up from standby mode in less than 1 μs

• Device parameters
  • Flash options: 1–120 KB
  • RAM options: 128 B – 8 KB
  • GPIO options: 10, 11, 16, 24, 32, and 48 pins
  • ADC options: Slope, 10 & 12-bit SAR, 16 & 24-bit Sigma Delta
  • Other integrated peripherals: operational amplifiers, 12-bit DAC, up to 2 16-bit timers, watchdog timer, brown-out reset, SVS, USI module (I²C, SPI), USCI module, DMA, 16×16 multiplier, Comparator_A+, temperature sensor

MSP430G2xx series

The MSP430G2xx Value Series features flash-based Ultra-Low Power MCUs up to 16 MIPS with 1.8–3.6 V operation. Includes the Very-Low power Oscillator (VLO), internal pull-up/pull-down resistors, and low-pin count options, at lower prices than the MSP430F2xx series.

• Ultra-Low Power, as low as (@2.2 V):
  • 0.1 μA RAM retention
  • 0.4 μA Standby mode (VLO)
  • 0.7 μA real-time clock mode
  • 220 μA / MIPS active
  • Ultra-Fast Wake-Up From Standby Mode in <1 μs

• Device parameters
  • Flash options: 0.5–56 KB
  • RAM options: 128 B–4 KB
  • GPIO options: 10, 16, 24, 32 pins
  • ADC options: Slope, 10-bit SAR
  • Other integrated peripherals: Capacitive Touch I/O, up to 3 16-bit timers, watchdog timer, brown-out reset, USI module (I²C, SPI), USCI module, Comparator_A+, Temp sensor

MSP430x3xx series

The MSP430x3xx Series is the oldest generation, designed for portable instrumentation with an embedded LCD controller. This also includes a frequency-locked loop oscillator that can automatically synchronize to a low-speed (32 kHz) crystal. This generation does not support EEPROM memory, only mask ROM and UV-eraseable and one-time programmable EPROM. Later generations provide only flash memory and mask ROM options. These devices offer 2.5–5.5 V operation, up to 32 KB ROM.

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 0.9 μA real-time clock mode
  • 160 μA / MIPS active
  • Features fast wake-up from standby mode in less than 6 μs.

• Device parameters:
  • ROM options: 2–32 KB
  • RAM options: 512 B–1 KB
  • GPIO options: 14, 40 pins
  • ADC options: Slope, 14-bit SAR
  • Other integrated peripherals: LCD controller, multiplier

MSP430x4xx series

The MSP430x4xx Series are similar to the '3xx generation, but include an integrated LCD controller, and are larger and more capable. These flash or ROM based devices offers 8–16 MIPS at 1.8–3.6 V operation, with FLL, and SVS. Ideal for low power metering and medical applications.

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 0.7 μA real-time clock mode
  • 200 μA / MIPS active
  • Features fast wake-up from standby mode in less than 6 μs.

• Device parameters:
  • Flash/ROM options: 4 – 120 KB
  • RAM options: 256 B – 8 KB
  • GPIO options: 14, 32, 48, 56, 68, 72, 80 pins
  • ADC options: Slope, 10 & 12-bit SAR, 16-bit Sigma Delta
  • Other integrated peripherals: SCAN_IF, ESP430, 12-bit DAC, Op Amps, RTC, up to 2 16-bit timers, watchdog timer, basic timer, brown-out reset, SVS, USART module (UART, SPI), USCI module, LCD Controller, DMA, 16×16 & 32x32 multiplier, Comparator_A, temperature sensor, 8 MIPS CPU Speed

MSP430x5xx series

The MSP430x5xx Series are able to run up to 25 MHz, have up to 512 KB flash memory and up to 66 KB RAM. This flash-based family features low active power consumption with up to 25 MIPS at 1.8–3.6 V operation (165 uA/MIPS). Includes an innovative power management module for optimal power consumption and integrated USB.^[5]

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 2.5 μA real-time clock mode
  • 165 μA / MIPS active
  • Features fast wake-up from standby mode in less than 5 μs.

• Device parameters:
  • Flash options: up to 512 KB
  • RAM options: up to 66 KB
  • ADC options: 10 & 12-bit SAR
  • GPIO options: 29, 31, 47, 48, 63, 67, 74, 87 pins
  • Other optional integrated peripherals: 12-bit DAC, High resolution PWM, 5 V I/O's, USB, backup battery switch, up to 4 16-bit timers, watchdog timer, Real-Time Clock, brown-out reset, SVS, USCI module, DMA, 32x32 multiplier, Comp B, temperature sensor

MSP430x6xx series

The MSP430x6xx Series are able to run up to 25 MHz, have up to 512 KB flash memory and up to 66 KB RAM. This flash-based family features low active power consumption with up to 25 MIPS at 1.8–3.6 V operation (165 uA/MIPS). Includes an innovative power management module for optimal power consumption and integrated USB.

• Power specification overview, as low as:
  • 0.1 μA RAM retention
  • 2.5 μA real-time clock mode
  • 165 μA / MIPS active
  • Features fast wake-up from standby mode in less than 5 μs.

• Device parameters:
  • Flash options: up to 512 KB
  • RAM options: up to 66 KB
  • ADC options: 12-bit SAR
  • GPIO options: 74 pins
  • Other integrated peripherals: USB, LCD, DAC, Comparator_B, DMA, 32x32 multiplier, power management module (BOR, SVS, SVM, LDO), watchdog timer, RTC, Temp sensor

RF SoC (CC430) series

The RF SoC (CC430) Series provides tight integration between the microcontroller core, peripherals, software, and RF transceiver. Features <1 GHz RF transceiver, with 1.8 V–3.6 V operation. Programming using Arduino integrated development environment (IDE) is possible via the panStamp API.

• Power specification overview, as low as:
  • 1 μA RAM retention
  • 1.7 μA real-time clock mode
  • 180 μA / MIPS active

• Device parameters:
  • Speed options: up to 20 MHz
  • Flash options: up to 32 KB
  • RAM options: up to 4 KB
  • ADC options: 12-bit SAR
  • GPIO options: 30 & 44 pins
  • Other integrated peripherals: LCD Controller, up to 2 16-bit timers, watchdog timer, RTC, power management module (BOR, SVS, SVM, LDO), USCI module, DMA, 32x32 multiplier, Comp B, temperature sensor

FRAM series

The FRAM Series from Texas Instruments provides unified memory with dynamic partitioning and memory access speeds 100 times faster than flash. FRAM is also capable of zero power state retention in all power modes, which means that writes are guaranteed, even in the event of a power loss. With a write endurance of over 100 trillion cycles, EEPROM is no longer required. Active power consumption at less than 100 μA/MHz.

• Power specification overview, as low as:
  • 320 nA RAM retention
  • 0.35 μA real-time clock mode
  • 82 μA / MIPS active

• Device parameters:
  • Speed options: 8 to 24 MHz
  • FRAM options: 4 to 256 KB
  • RAM options: 0.5 to 8 KB
  • ADC options: 10 or 12-bit SAR
  • GPIO options: 17 to 83 GPIO pins
  • Other possible integrated peripherals: MPU, up to 6 16-bit timers, watchdog timer, RTC, power management module (BOR, SVS, SVM, LDO), USCI module, DMA, multiplier, Comp B, temperature sensor, LCD driver, I2C and UART BSL, Extended Scan Interface, 32 bit multiplier, AES, CRC, signal processing acceleration, capacitive touch, IR modulation

Low voltage series

The Low Voltage Series include the MSP430C09x and MSP430L092 parts, capable of running at 0.9 V. These 2 series of low voltage 16-bit microcontrollers have configurations with two 16-bit timers, an 8-bit analog-to-digital (A/D) converter, an 8-bit digital-to-analog (D/A) converter, and up to 11 I/O pins.

• Power specification overview, as low as:
  • 1 μA RAM retention
  • 1.7 μA real-time clock mode
  • 180 μA / MIPS active

• Device parameters:
  • Speed options: 4 MHz
  • ROM options: 1–2 KB
  • SRAM options: 2 KB
  • ADC options: 8-bit SAR
  • GPIO options: 11 pins
  • Other integrated peripherals: up to 2 16-bit timers, watchdog timer, brown-out reset, SVS, comparator, temperature sensor

Other MSP430 families

More families within MSP430 include Fixed Function, Automotive, and Extended Temp parts.

Fixed Function: The MSP430BQ1010 16-bit microcontroller is an advanced fixed-function device that forms the control and communications unit on the receiver side for wireless power transfer in portable applications. MSP430BQ1010 complies with the Wireless Power Consortium (WPC) specification. For more information, see Contactless Power^{[permanent dead link]}.

Automotive: Automotive MSP430 microcontrollers (MCUs) from Texas Instruments (TI) are 16-bit, RISC-based, mixed-signal processors that are AEC-Q100 qualified and suitable for automotive applications in environments up to 105 °C ambient temperature. LIN compliant drivers for the MSP430 MCU provided by IHR GmbH.

Extended Temp: MSP430 devices are very popular in harsh environments such as industrial sensing for their low power consumption and innovative analog integration. Some harsh environment applications include transportation/automotive, renewable energy, military/space/avionics, mineral exploration, industrial, and safety & security.

• Device Definitions:
  • HT: -55 °C to 150 °C
  • EP: Enhanced products -55 °C to 125 °C
  • Q1: Automotive Q100 qualified -40 °C to 105 °C
  • T: Extended temperature -40 °C to 105 °C applications

Note that when the flash size is over 64K words (128 KBytes), instruction addresses can no longer be encoded in just two bytes. This change in pointer size causes some incompatibilities with previous parts.

Peripherals

The MSP430 peripherals are generally easy to use, with (mostly) consistent addresses between models, and no write-only registers (except for the hardware multiplier).

General purpose I/O ports 0–10

If the peripheral is not needed, the pin may be used for general purpose I/O. The pins are divided into 8-bit groups called "ports", each of which is controlled by a number of 8-bit registers. In some cases, the ports are arranged in pairs which can be accessed as 16-bit registers.

The MSP430 family defines 11 I/O ports, P0 through P10, although no chip implements more than 10 of them. P0 is only implemented on the '3xx family. P7 through P10 are only implemented on the largest members (and highest pin count versions) of the '4xx and '2xx families. The newest '5xx and '6xx families has P1 through P11, and the control registers are reassigned to provide more port pairs. Each port is controlled by the following registers. Ports which do not implement particular features (such as interrupt on state change) do not implement the corresponding registers.

PxIN

Port x input. This is a read-only register, and reflects the current state of the port's pins.

PxOUT

Port x output. The values written to this read/write register are driven out the corresponding pins when they are configured to output.

PxDIR

Port x data direction. Bits written as 1 configure the corresponding pin for output. Bits written as 0 configure the pin for input.

PxSEL

Port x function select. Bits written as 1 configure the corresponding pin for use by the specialized peripheral. Bits written as 0 configure the pin for general purpose I/O. Port 0 ('3xx parts only) is not multiplexed with other peripherals and does not have a P0SEL register.

PxREN

Port x resistor enable ('2xx & '5xx only). Bits set in this register enable weak pull-up or pull-down resistors on the corresponding I/O pins even when they are configured as inputs. The direction of the pull is set by the bit written to the PxOUT register.

PxDS

Port x drive strength ('5xx only). Bits set in this register enable high current outputs. This increases output power, but may cause electromagnetic interference (EMI).

Ports 0–2 can produce interrupts when inputs change. Further registers configure this ability:

PxIES

Port x interrupt edge select. Selects the edge which will cause the PxIFG bit to be set. When the input bit changes from matching the PxIES state to not matching it (i.e. whenever a bit in PxIES XOR PxIN changes from clear to set), the corresponding PxIFG bit is set.

PxIE

Port x interrupt enable. When this bit and the corresponding PxIFG bit are both set, an interrupt is generated.

PxIFG

Port x interrupt flag. Set whenever the corresponding pin makes the state change requested by PxIES. Can be cleared only by software. (Can also be set by software.)

PxIV

Port x interrupt vector ('5xx only). This 16-bit register is a priority encoder which can be used to handle pin-change interrupts. If n is the lowest-numbered interrupt bit which is pending in PxIFG and enabled in PxIE, this register reads as 2n+2. If there is no such bit, it reads as 0. The scale factor of 2 allows direct use as an offset into a branch table. Reading this register also clears the reported PxIFG flag.

Some pins have special purposes either as inputs or outputs. (For example, timer pins can be configured as capture inputs or PWM outputs.) In this case, the PxDIR bit controls which of the two functions the pin performs when the PxSEL bit is set. If there is only one special function, then PxDIR is generally ignored. The PxIN register is still readable if the PxSEL bit is set, but interrupt generation is disabled. If PxSEL is clear, the special function's input is frozen and disconnected from the external pin. Also, configuring a pin for general purpose output does not disable interrupt generation.