Author ：Iflowpower – Portable Power Station Supplier
Many system designers believe that the power consumption consumed by the single chip is less than the two chips. Originally, it is very simple: chip communication consumes more power consumption than a single chip, there are more transistors on both chips, so there are more leakage currents with single-chip with the same function. But power consumption technology has given this kind of traditional point of view.
DSP designers integrate more features, such as accelerators, communication modules, and network peripherals to the DSP chip, making the chip more useful to engineers. But this more powerful chip will consume more power consumption than this task in completing simple in-house management or monitoring tasks. In many cases, the designer cannot only enable the features required in the DSP chip.
In some uses, the microcontroller (MCU) can perform the same system monitoring task, and consume less power consumption than DSP. So, the architecture of the double chip: DSP and MCU are also possible. Therefore, use a low-power DSP as a main solution, another low power MCU as a system monitor, can extend the battery life consumed by the single DSP to complete the same task.
To help save power, engineers should consider the following factors when choosing DSP: look for larger capacity on-chip memory. DSP always consumes more power consumption when accessing the chip exterior memory. External DRAM stores constant power consumption, which consumes battery electrical energy.
Select a DSP that can be started and closed peripherals. Some DSPs can automatically power off on the inactive on-chip peripherals, which supplies a variety of control and power consumption provinces. Select a DSP that enables a variety of standby states at different power levels.
Multi-power supply saves more energy consumption. Choose DSP for the development software that optimizes power consumption and reduces power consumption. The tool should make developers easily change the voltage and frequency of the chip, manage power status, help them evaluate and decompose power consumption information.
MCU consumes less current in some MCUs in some uses, low-power semiconductor process reduces transistor leakage current to help chip designers optimize low power operation. Unfortunately, low power consumption will limit MCU performance. For example, a TEXASINSTRUMENTSMSP430MCU consumes 500NA current in standby mode, the maximum clock frequency is 16MHz.
The maximum clock frequency running in TMS320C5506DSP is 108MHz, consumes 10 in standby mode.µA current. This declares that it consumes 20 times higher than the MSP430.
From the development of the past, the internal MCU peripheral has been controlled by the software, which is stateable to maintain the status of the CPU. But the new interrupt drive (Interrupt-Driven) is peripheral for less software overhead, allows MCU to keep standby mode in most time. Take the internal modulus converter (ADC) hardware as an example, it automatically scans the input channel, trigger conversion, and execute DMA transmission to solve the received data sampling task.
As a result, the ADC is almost spontaneously running. The CPU only uses very little time for its supply service, and the MCU saves power consumption. Multiple clock reduction power requirements MCU clock system design can also help reduce power consumption.
The circuit diagram in Figure 1 shows two clocks operating by a single crystal. The MCU usually uses a 32kHz crystal, but does not necessarily generate internal clock signals, system clock (MCLK), and secondary clock (ACLK) signals. Typically, crystals only generate ACLK signals.
MCU's low-power extraction using a 32kHz auxiliary clock that simultaneously drives the MCU real-time clock, high-speed digital control oscillator (DCO) generates a system clock signal for CPU and high-speed peripherals. DCO can generate clock signals in several ways, each with different performance and power consumption characteristics. From low to high power consumption, these clock modes have ultra low power oscillators (VLO), 3kHz crystals to DCO.
In order to reduce power consumption, the designer uses the lowest clock (VLO or 32kHz crystal) in idle mode, and realizes high frequency DCO when using the activity to be used to CPU. DCO can be less than 1µThe time of S's time enters the active state and is fully stable. This instant enabled capability saves time and power consumption.
Note that using low-frequency low-power clocks in the activity resolution will consume more power consumption than switching to faster clocks. In higher power-consuming mode, low frequency time bells the CPU spend more time on a specific task. In addition to using low-speed clock-saving power consumption on certain peripherals, the MSP430MCU also supplies ultra-low power oscillators to generate an ACLK signal.
Under its standby power mode (LPM3), MSP430MCU usually consumes less than 1 in ACLK operation and all interrupt enabled states.µA current. Therefore, low-power MCUs consume less power than DSP during the real-time clock or management battery charging.
Moreover, the mission to the MCU can also be freed by the DSP to make it executable to signal resolution tasks. Power consumption saving results engineers can see dual-demand design to achieve excellent results. Imagine a system that relies on high-end DSP to solve monitoring tasks.
This solution will soon use a 2,500mAh nickel-hydrogen AA battery. If the uniform current consumption is 10mA, the two series batteries will be exhausted within 10.5 days.
Dual Split Use to reduce current to 1mA, so that the battery is extended to 120 days. The MCU in the dual-solution system is to reduce power consumption, some system or monitoring functions that can be solved include: Real Time Clock Maintenance Power Sort Power Significance and Reset Keyboard or Human Interface Management Battery Management Display Control DSP Power Many DSPs A plurality of power rails of the power supply are applied in a fixed order to ensure normal working in DSP and peripherals. Typically, these tracks simultaneously powered by core (CPU) and DDR memory and I / O devices.
Although dedicated devices can apply a voltage to the DSP chip by fixed order, it cannot perform other functions. Smaller low-power MCUs can be sorted and monitored for power supply voltage, and perform power control tasks (Figure 2). In this case, the software starts three power supply regulator circuits in an appropriate order.
The MCU uses its internal ADC to test the appropriate voltage when the respective power rails. When the total circuit does not want a DSP chip, the MCU can enclose the regulator to close the DSP. In fact, the MCU can communicate with the pressure-controlled oscillator to control the voltage and frequency of the DSP, or the clock frequency of the PLL communication control DSP.
Therefore, when the DSP completes the computational dense task, the MCU adjustable clock converts the DSP to standby mode to save power consumption. Two-way monitoring MCU test DSP to understand its busy state. In this mode, the MCU is running as a smart controller.
On the other hand, DSP can read and write the MCU. So the DSP can be used according to the usage, inform the MCU to reduce or improve the DSP clock. Using the MCU to complete other tasks that DSPs usually achieve in a single solution system, designers can also get more benefits.
For example, when resolving keyboard operation, MCU consumes less power consumption than DSP. The MCU only sends an interrupt signal to the DSP after testing the action of the button or the release of the button. This way helps the excessive current consumption caused by hit by the hit, this situation often out in some handheld equipment.
In order to further relieve the load of the DSP chip, the MCU can supply: the driving circuit standard SPI, UART, and I2C ports for radio frequency communication peripheral interface battery management circuit universal I / O ports mentioned on the above and previous Each peripheral, the MCU can automatically start from low power mode. Therefore, the MCU does not continue to poll the peripherals to determine which one to serve, nor does the maximum power consumption to carry out the task. Peripherals will start.
Each milliwat in low power consumption is very precious. Finally, designers are not based on comprehensive considerations between calculations, measurement, and functions and running DSP or MCUs, and use one or two Satures in use.
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