Stm32f4 DMA Da sine wave generator keil5 Hal library cubemx

One 、 introduction

In the previous two articles , The design idea of frequency meter and square wave generator with adjustable duty cycle is explained . This article explains the design idea of sine wave generator .

Frequency meter ：https://blog.csdn.net/zzlwl/article/details/115352504

Square wave generator ：https://blog.csdn.net/zzlwl/article/details/114882800

At the beginning of the design , in consideration of stm32f4 dma Superior performance , Determined to use dma Carry out the design goal of sine wave generator .

Search data stage , Refer to the routine of punctual atom , But there is no routine for continuous sine wave occurrence . give up .

I found an introduction on the Internet dma Sine wave article , However, it is found that the overload value of its timer has a strange suspense that it only works at a specific value . give up .

During this time, I have been studying CubeMX, Determined to use CubeMX The idea of sine wave generator .

Final realization ：1hz-31.25khz（ Sine meter 32 Point to 256 Dynamic jump between points ） Sine generator , The maximum frequency interval in this range is approximately equal to the current setting value 2%, The minimum is 0（ It depends on factorization , Without theoretical proof ）

Two 、 The main data

（1） Buffered or unbuffered ？

Look up  stm32F40x-2015-3-ID022152v5 The findings are as follows ：

obviously , No buffering is better than buffering .

（2） Speed and frequency

Same as above

obviously , The maximum update rate is 1us,6us I'm sure it can be updated . If 32 spot , Then the highest frequency 1000/32=31.25K

Plan to make the timer count at 80M, The frequency division number is 7（8 frequency division ） Add one digit each time 0.1us. Because the maximum update speed is 1us, Therefore, the minimum value of timer is 9（1us）

3、 ... and 、CubeMX Set up

Enable usart1、dma、dac1 tim6, stay cubeMx To establish dma、dac1、tim6 The connection between . Change the frequency division number in the number of clocks , Let the master clock work at 160Mhz

（CubeMX Please refer to the previous two articles for graphical use ）

keil RTE HAL library STM32CubeMX Serial transceiver  https://blog.csdn.net/zzlwl/article/details/115431728

Keil RTE Flash program  https://blog.csdn.net/zzlwl/article/details/115394066

Four 、 The core idea of the code

（1） Call the interrupt receiving function in the main program     

      HAL_UART_Receive_IT(&huart1,&(rxData.buff[0]),1); Start interrupt reception

        In the callback function void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) Format check in , If a carriage return line feed is received, the command input is considered complete , Otherwise, continue to interrupt the reception .

（2） Generate 256 Point sine meter , And start the timer , start-up dma, Start preset frequency output

       HAL_TIM_Base_Start(&htim6);
       HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t *)sinTbl, 256,DAC_ALIGN_12B_R);

    From the above we can calculate , The preset frequency value is 10,000,000/256/10=3.906K

(10,000,000 by 1 In the second 0.1us The number of ,256 Indicates that the sine meter has 256 A little bit ,10 Indicates the auto reload value of the current timer . Timers every 0.1us Add 1)

（3） Main loop task processing

      Complete data input in the main loop , Scope check , Factorization , Reset the timer and dma The job of .

（3.1） Calculate the optimal combination of timing value and sine number

            If data entry is valid , Then calculate the periodic value according to the frequency （ Company 0.1us）, If the period value >256*10, Then 256 spot , Otherwise, the optimal factorization in a step .

            The meaning of a step , Such as the number of cycles <256*10, but >128*10  Then the number of points is guaranteed >128 In the case of circular judgment , Find the best number of points And timer timing value . The so-called optimal , It refers to the minimum error between the above two integer numbers multiplied and the set cycle value .

（3.2） Regenerate sine table , Reset the timer and dma

            __HAL_TIM_SET_AUTORELOAD(&htim6,arr-1);// Reset the timer according to the actual timer time
           HAL_DAC_Stop_DMA(&hdac, DAC_CHANNEL_1); // If you don't close it first dma Then the following reset points will not work .   
            HAL_DAC_Start_DMA(&hdac, DAC_CHANNEL_1, (uint32_t *)sinTbl, npoint,DAC_ALIGN_12B_R);//dma Start   

Reset timer macro from file #include "stm32f4xx_hal_tim.h", If you are prompted with a compilation error , You can add this file .

5、 ... and 、 After commissioning

This project is in addition to the code mentioned above , Sine table generation 、 Serial receive callback function 、 Optimize timing and sine point code to write for yourself , Other codes are automatically generated by the system . Sensory use CubeMX More clear thinking , In addition, some macros can be used directly do while Packaging implementation , It feels like it takes into account both concept and speed . But there are few Chinese materials , For programmers C level 、 Foreign language proficiency is required .