The MSP430G2553 single-chip microcomputer is called a mixed-signal processor because it integrates multiple analog circuits, digital circuit modules and microprocessors with different functions on a single chip to provide a "single-chip" solution for practical application requirements. This series of single-chip microcomputers are mostly used in portable instruments that require battery power.
The MSP430 series microcontrollers introduced by Texas Instruments (TI) can achieve extremely low processor power consumption and are particularly suitable for battery-powered applications. This article takes MSP430G2553 microcontroller as an example to discuss its realization of ultra-low power consumption design in more detail. The MSP430 series single-chip microcomputers have ultra-low power consumption characteristics, but also have strong data processing and computing capabilities, high-performance analog technology, rich on-chip modules, and a convenient and efficient development and debugging environment.
The MSP430G2553 microcontroller is a mixed-signal microcontroller with a 16-bit reduced instruction set (RISC) architecture and 62.5 ns instruction cycle time. It can wake up from standby mode ultra-fast in less than 1μs and supports JTAG simulation debugging . Ultra-low power consumption: 1.8～3.6 V low power supply voltage; under the conditions of 1 MHz frequency and 2.2 V voltage, there are 230μA/operation mode, 0.5μA/standby mode, 0.1μA/off Mode (RAM retention); the input leakage current of the port line is less than 50 nA.
The MSP430 series development tools are convenient and advanced. This article is based on the MSP430G2553 single-chip microcomputer for ultra-low power research. The related experiments use the MSP430 LaunchPad development board. The single-chip microcomputer is packaged in 20-pin PDIP. The compilation tool uses Code Composer Studio v5.1. Software programming. Using C language.
The MSP430 series single-chip microcomputer is a representative of ultra-low power single-chip microcomputers. It has a flexible clock system, a variety of deep low-power modes, and highly automated intelligent peripherals. It makes full use of the features and internal modules of MSP430G2553 to achieve ideal low-power Consuming characteristics.
MSP430G2553 is a typical low-power system CPU working mode. The system is idle most of the time, and some tasks will be processed only when an event occurs or timing. The power consumption of the entire system is equal to the area under the average curve. Reduce system power consumption, that is, select low power consumption mode when idle, and minimize work consumption when running.
● Idle state
Many low-power systems consume more than 80% of the energy in the idle state, so try to choose a deep sleep mode in the idle state. The MSP430 series single-chip microcomputer provides a variety of working modes, as listed in Table 1, which can make flexible switch control for the system clock and auxiliary clock. Generally, the method of maximizing the LPM3 time is adopted to minimize the power consumption. The MSP430 series single-chip microcomputer can switch the working mode quickly and conveniently. The CPU can be awakened from the low-power mode within 6μs through interrupts to control the program flow. Due to the fast processing speed of the CPU and the short exiting low-power consumption time, most of the CPU can be guaranteed The time is in an idle state, which reduces the power consumption of the microcontroller system.
● Running status
Among them: P is the CMOS digital system power in the running state, C is the CMOS load capacitance, f is the system clock frequency, and Vcc is the power supply voltage.
It can be seen that the power supply voltage has the greatest impact on the power consumption of the system, followed by the clock frequency, and then the load capacitance. For users, the load capacitance is generally uncontrollable, so to design a low-power MCU system, there are two main principles: reduce the power supply voltage as much as possible; reduce the clock frequency as much as possible. Other methods are basically implemented around these two principles.
● Power supply voltage
The higher the power supply voltage at the same main frequency, the higher the power consumption. It is necessary to design a reasonable power supply system and flexibly adjust the microcontroller core voltage to reduce power consumption. The typical values of Vcc and Icc under AM are listed in Table 2. In the active mode (AM), the power supply current (Icc) of the MSP430G2553 microcontroller changes with the power supply voltage (Vcc).
● Clock frequency
The clock system of MSP430G2553 is specially designed for battery power supply. The MSP430G2553 microcontroller has different clock sources and generates 3 adjustable clock frequencies: low-frequency auxiliary clock (ACLK), high-frequency main system clock (MCLK) and high-frequency subsystem clock (SMCLK). Weigh the frequency of the three clocks according to the actual needs of each peripheral module, the highest processor speed requirements, and clock accuracy. For some low-frequency peripherals, ACLK can be used as a clock or signal source instead of using MCLK uniformly to reduce power consumption; whether for CPU or external devices, the operating frequency should be reduced as much as possible, and automatic shutdown can be designed when the function is not affected.
● I/O port
For ordinary I/O ports, it is necessary to configure the output mode to avoid the influence of external floating voltage. CMOS input terminals cannot have floating pins, and all input terminals should be connected to appropriate levels.
● External equipment
Configure appropriate working modes for on-chip external devices, and do appropriate power management for external devices in the system to reduce power consumption and reduce CPU usage. In specific applications, it is recommended to disable all unused peripheral modules, and use ADC converters with enable pins, operational amplifiers with enable pins, etc.
● Intelligent peripherals
Make full use of the intelligent peripherals of MSP430G2553, so that it can work independently of the CPU, so that the system stays in low power consumption mode for a longer time. For example, ADC10 can realize multi-channel automatic polling and sampling, and can realize automatic transfer of ADC conversion results. Through reasonable configuration of registers, the load of the CPU can be minimized, thereby achieving the purpose of reducing power consumption.
The linkage between DMA and other peripherals, and the timer automatically triggers ADC functions can realize intelligent operation between different modules on the chip and reduce system power consumption.
● Software programming
The simplicity of the software design is directly related to the time required for the CPU to complete the task. MSP430G2553 has a unified addressing space, a completely orthogonal instruction system and sufficient general-purpose registers, which can ensure the high efficiency of C language compilation.
But at the same time in system design, software engineers are required to carry out the most concise code design, as follows:
1. Use local variables as much as possible. Local variables are usually allocated to general-purpose registers, which has high instruction efficiency;
2. Try to use unsigned numbers;
3. Use pointers to address structures and unions;
4. Decrease the counter data when using the fox loop;
5. Try to use quick table lookup instead of algorithm calculation, and try to use calculation branches instead of testing flags.
Manufacturer: Texas Instruments
IC DSP FIXED/FLOAT POINT 256BGA
Product Categories: DSP
IC MCU 32BIT 128KB FLASH 64QFN
Product Categories: 32bit MCU
Manufacturer: Texas Instruments
IC DSP FIXED-POINT 196NFBGA
Product Categories: DSP
Looking forward to your comment