基于Acconeer的A121-60GHz毫米波雷达传感器SDK移植及测距示例（STM32L496为例）
工程：
Keil工程资源
参考资料：
A121 datasheet 1.3
A121 HAL Software Integration User Guide
A121 STM32CubeIDE User Guide
官方参考示例工程：
XM125_MDK-AC5_A121_v1_0_0
（XM125相当于A121的最小系统板 硬件连接与裸机相同）
文章目录
- A121
- 引脚配置
- SDK移植
- RSS的SDK移植
- SDK移植函数
- SPI传输函数
- 等待中断函数
- 延时函数修改
- 函数指针赋值
- SDK示例移植
- 堆栈配置
- 测试SDK
- 上电测试
- 测距测试
- 附录：Cortex-M架构的SysTick系统定时器精准延时和MCU位带操作
- SysTick系统定时器精准延时
- 延时函数
- 阻塞延时
- 非阻塞延时
- 位带操作
- 位带代码
- 位带宏定义
- 总线函数
- 一、位带操作理论及实践
- 二、如何判断MCU的外设是否支持位带
A121
该传感器与MCU连接只需要一组SPI和一个中断GPIO、一个使能控制GPIO
且SPI的CPOL和CPHA都为0（空闲时低电平 且在第一个变化沿进行采样）
SPI速度可以达到50MHz 但不建议
A121作为从机使用 所以输出引脚为MISO 输入引脚为MOSI
引脚配置
与A121 STM32CubeIDE User Guide中介绍的基本相同
但建议SPI的速度设置为10M以下 并且选择8位数据传输
同时选中软件片选
关闭NSSP
之所以要选中如下配置 可以参考：
【STM32】HAL库中的SPI传输（可利用中断或DMA进行连续传输）
同时开启中断
GPIO配置：
包括软件片选 使能和中断
同样得开启GPIO中断
SDK移植
主要参考A121 HAL Software Integration User Guide中的内容
详细介绍了该如何进行移植前的配置
如：
也可以直接参考XM125_MDK-AC5_A121_v1_0_0示例工程来进行配置
其被移植部分的工程结构如下：
RSS的SDK移植
如图 将相关头文件拷贝到工程目录后 建议新建一个头文件用于导入这些库
比如：
#ifndef __A121_H__
#define __A121_H__
#include "main.h"
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <assert.h>
#include <complex.h>
#include <math.h>#include "acc_config.h"
#include "acc_config_subsweep.h"
#include "acc_definitions_a121.h"
#include "acc_definitions_common.h"
#include "acc_detector_distance.h"
#include "acc_detector_distance_definitions.h"
#include "acc_detector_presence.h"
#include "acc_hal_definitions_a121.h"
#include "acc_processing.h"
#include "acc_rss_a121.h"
#include "acc_sensor.h"
#include "acc_version.h"#include "acc_hal_integration_a121.h"
#include "acc_integration.h"
#include "acc_integration_log.h"#include "acc_control_helper.h"
#include "acc_processing_helpers.h"#include "ref_app_smart_presence.h"
#include "ref_app_tank_level.h"#include "example_service_subsweeps.h"
#include "example_service_multiple_configurations.h"
#include "example_service_hibernate.h"
#include "example_service.h"
#include "example_processing_subtract_adaptive_bg.h"
#include "example_processing_peak_interpolation.h"
#include "example_processing_noncoherent_mean.h"
#include "example_processing_coherent_mean.h"
#include "example_processing_amplitude.h"
#include "example_diagnostic_test.h"
#include "example_detector_presence_multiple_configurations.h"
#include "example_detector_presence.h"
#include "example_detector_distance_recorded_threshold.h"
#include "example_detector_distance_close_range.h"
#include "example_detector_distance.h"
#include "example_control_helper.h"
#include "example_bring_up.h"void Init_A121(void);#endif当然 rss/lib目录下的静态库也要导入
并且静态库要配置为library file
SDK移植函数
位于integration目录下
除了头文件外 需要覆写三个.c文件中的函数
在这里 需要把工程中不同的引脚名称重新定义以下
比如：
#define A121_SPI_HANDLE A121_SPI_Handle#define SPI_SS_GPIO_Port A121_SPI_CS_GPIO_Port
#define SPI_SS_Pin A121_SPI_CS_Pin#define ENABLE_GPIO_Port A121_EN_GPIO_Port
#define ENABLE_Pin A121_EN_Pin#define INTERRUPT_GPIO_Port A121_EXTI_GPIO_Port
#define INTERRUPT_Pin A121_EXTI_Pin
stm32.c中的不用改 只是一些基本延时、内存操作
log.c中注释掉fflush(stdout);（这里是清空stdout的语句 其中printf需要进行重定向 如果重定向过了 就不需要这一句了）
重定向参考：
【STM32】HAL库UART串口配置及重定向（解决接收中断与scanf不能同时工作、重定向卡死、低功耗一直唤醒的问题）
xm125.c中的函数需要进行更改：
前文说到 xm125就是A121的最小系统板 所以硬件的连接是一样的 所以可以直接拿来移植
SPI传输函数
前文说到 我们配置的SPI是8位传输
所以这里需要建立一个8位SPI传输函数
示例工程上的函数是16位 直接改成8位即可
同样 我这里是用中断的方式来进行连续传输的（如果要使用10M以上的连续传输 则替换成DMA的方式）
static void acc_hal_integration_sensor_transfer8(acc_sensor_id_t sensor_id, uint8_t *buffer, size_t buffer_length){(void)sensor_id; // Ignore parameter sensor_id// Set SPI_SS LOW (Activate)HAL_GPIO_WritePin(SPI_SS_GPIO_Port, SPI_SS_Pin, GPIO_PIN_RESET);//const uint32_t SPI_TRANSMIT_RECEIVE_TIMEOUT = 5000;#ifdef A121_USE_SPI_DMAspi_transfer_complete = false;HAL_StatusTypeDef status = HAL_SPI_TransmitReceive_DMA(&A121_SPI_HANDLE, (uint8_t *)buffer, (uint8_t *)buffer, buffer_length);if (status != HAL_OK){return;}uint32_t start = HAL_GetTick();while (!spi_transfer_complete && (HAL_GetTick() - start) < SPI_TRANSMIT_RECEIVE_TIMEOUT){// Turn off interruptsdisable_interrupts();// Check once more so that the interrupt have not occurredif (!spi_transfer_complete){__WFI();}// Enable interrupt again, the ISR will execute directly after thisenable_interrupts();}
#elseHAL_SPI_TransmitReceive_IT(&A121_SPI_HANDLE, (uint8_t *)buffer, (uint8_t *)buffer, buffer_length);while(A121_SPI_HANDLE.State!=HAL_SPI_STATE_READY && A121_SPI_HANDLE.State!=HAL_SPI_STATE_ERROR);
#endif// Set SPI_SS HIGH (De-activate)HAL_GPIO_WritePin(SPI_SS_GPIO_Port, SPI_SS_Pin, GPIO_PIN_SET);
}等待中断函数
这里是官方写法 但是SysTick在我的工程中会关闭 可以替换成其他的超时计算方式
bool acc_hal_integration_wait_for_sensor_interrupt(acc_sensor_id_t sensor_id, uint32_t timeout_ms)
{(void)sensor_id; // Ignore parameter sensor_idconst uint32_t wait_begin_ms = HAL_GetTick();while ((HAL_GPIO_ReadPin(INTERRUPT_GPIO_Port, INTERRUPT_Pin) != GPIO_PIN_SET) &&(HAL_GetTick() - wait_begin_ms < timeout_ms)){// Wait for the GPIO interruptdisable_interrupts();// Check again so that IRQ did not occurif (HAL_GPIO_ReadPin(INTERRUPT_GPIO_Port, INTERRUPT_Pin) != GPIO_PIN_SET){__WFI();}// Enable interrupts again to allow pending interrupt to be handledenable_interrupts();}return HAL_GPIO_ReadPin(INTERRUPT_GPIO_Port, INTERRUPT_Pin) == GPIO_PIN_SET;
}
延时函数修改
为了避免HAL库的延时函数出错 统一换成我们自己的延时函数
void acc_hal_integration_sensor_enable(acc_sensor_id_t sensor_id)
{(void)sensor_id; // Ignore parameter sensor_idHAL_GPIO_WritePin(ENABLE_GPIO_Port, ENABLE_Pin, GPIO_PIN_SET);HAL_GPIO_WritePin(SPI_SS_GPIO_Port, SPI_SS_Pin, GPIO_PIN_SET);// Wait 2 ms to make sure that the sensor crystal have time to stabilizedelay_ms(2);
}void acc_hal_integration_sensor_disable(acc_sensor_id_t sensor_id)
{(void)sensor_id; // Ignore parameter sensor_idHAL_GPIO_WritePin(SPI_SS_GPIO_Port, SPI_SS_Pin, GPIO_PIN_RESET);HAL_GPIO_WritePin(ENABLE_GPIO_Port, ENABLE_Pin, GPIO_PIN_RESET);// Wait after disable to leave the sensor in a known state// in case the application intends to enable the sensor directlydelay_ms(2);
}
函数指针赋值
最后把定义的函数指针全部赋值到结构体内即可
这里需要注意的是 8位SPI传输和16位SPI传输选其一即可 我们用的8位 所以16位对应的函数为NULL
const acc_hal_a121_t *acc_hal_rss_integration_get_implementation(void)
{static const acc_hal_a121_t val ={.max_spi_transfer_size = STM32_MAX_TRANSFER_SIZE,.mem_alloc = malloc,.mem_free = free,.transfer = acc_hal_integration_sensor_transfer8,.log = acc_integration_log,.optimization.transfer16 = NULL,};return &val;
}
SDK示例移植
直接移植即可
其中 acc_processing_helpers.c这里用到了<complex.h>头文件 用于复数操作 但多数AC5编译器不支持 可以换成AC6 不过我这里没用到相关函数 所以没有进行配置
堆栈配置
如图：
其中 在函数acc_example_bring_up中 用于分配内存
雷达数组大小ACC_RSS_ASSEMBLY_TEST_MIN_BUFFER_SIZE是2048 所以还是给大一点堆栈空间好
测试SDK
官方示例中给出了几个函数用于测试各种功能
acc_example_bring_up(0,NULL); //测试雷达与MCU的通讯是否正常，A121雷达外部电路是否正常。acc_example_service(0,NULL); //原始数据。高精度测距，复杂场景测距从此入手。acc_example_detector_distance(0,NULL); //距离检测器，适用于简单场景测距。acc_example_detector_presence(0,NULL); //存在检测器，可用于人体检测。acc_example_processing_amplitude(0,NULL); //从Sparse IQ服务的原始数据提取距离信息的处理方法。
上电测试
调用acc_example_bring_up(0,NULL); 函数即可
输出效果：
其中 A121开头的为SDK中的函数运行输出
测距测试
调用acc_example_detector_distance(0,NULL); 函数即可
输出效果：
其中 A121开头的为SDK中的函数运行输出
该示例可以输出多个目标
同时会在开始测距之前初始化相关配置：
[A121] Acconeer software version a121-v1.0.0
[A121] 00:00:00.000 (I) (detector_distance) Detector Distance Config
[A121] 00:00:00.000 (I) (detector_distance) sensor: 1
[A121] 00:00:00.000 (I) (detector_distance) start_m: 0.250000
[A121] 00:00:00.000 (I) (detector_distance) end_m: 3.000000
[A121] 00:00:00.000 (I) (detector_distance) max_step_length: 0
[A121] 00:00:00.000 (I) (detector_distance) max_profile: PROFILE_5
[A121] 00:00:00.000 (I) (detector_distance) signal_quality: 15.000000
[A121] 00:00:00.000 (I) (detector_distance) threshold_method: CFAR
[A121] 00:00:00.000 (I) (detector_distance) peak_sorting_method: STRONGEST
[A121] 00:00:00.000 (I) (detector_distance) num_frames_in_recorded_threshold: 100
[A121] 00:00:00.000 (I) (detector_distance) fixed_threshold_value: 100.000000
[A121] 00:00:00.000 (I) (detector_distance) threshold_sensitivity: 0.500000
[A121] 00:00:00.000 (I) (detector_distance) Offset Calibration Config
[A121] 00:00:00.000 (I) (config) sweep_rate: 0.000000
[A121] 00:00:00.000 (I) (config) frame_rate: 0.000000
[A121] 00:00:00.000 (I) (config) sweeps_per_frame: 1
[A121] 00:00:00.000 (I) (config) continuous_sweep_mode: false
[A121] 00:00:00.000 (I) (config) double_buffering: false
[A121] 00:00:00.000 (I) (config) inter_frame_idle_state: DEEP_SLEEP
[A121] 00:00:00.000 (I) (config) inter_sweep_idle_state: READY
[A121] 00:00:00.000 (I) (config) num_subsweeps: 1
[A121] 00:00:00.000 (I) (config) subsweep: 0
[A121] 00:00:00.000 (I) (config) start_point : -30
[A121] 00:00:00.000 (I) (config) num_points : 50
[A121] 00:00:00.000 (I) (config) step_length : 1
[A121] 00:00:00.000 (I) (config) hwaas : 64
[A121] 00:00:00.000 (I) (config) receiver_gain : 16
[A121] 00:00:00.000 (I) (config) enable_tx : true
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : true
[A121] 00:00:00.000 (I) (config) prf : PROFILE_1
[A121] 00:00:00.000 (I) (config) profile : 13.0MHz
[A121] 00:00:00.000 (I) (detector_distance) Far Noise Calibration
[A121] 00:00:00.000 (I) (config) sweep_rate: 0.000000
[A121] 00:00:00.000 (I) (config) frame_rate: 0.000000
[A121] 00:00:00.000 (I) (config) sweeps_per_frame: 1
[A121] 00:00:00.000 (I) (config) continuous_sweep_mode: false
[A121] 00:00:00.000 (I) (config) double_buffering: false
[A121] 00:00:00.000 (I) (config) inter_frame_idle_state: DEEP_SLEEP
[A121] 00:00:00.000 (I) (config) inter_sweep_idle_state: READY
[A121] 00:00:00.000 (I) (config) num_subsweeps: 4
[A121] 00:00:00.000 (I) (config) subsweep: 0
[A121] 00:00:00.000 (I) (config) start_point : 0
[A121] 00:00:00.000 (I) (config) num_points : 220
[A121] 00:00:00.000 (I) (config) step_length : 1
[A121] 00:00:00.000 (I) (config) hwaas : 2
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : false
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_1
[A121] 00:00:00.000 (I) (config) profile : 19.5MHz
[A121] 00:00:00.000 (I) (config) subsweep: 1
[A121] 00:00:00.000 (I) (config) start_point : 0
[A121] 00:00:00.000 (I) (config) num_points : 220
[A121] 00:00:00.000 (I) (config) step_length : 1
[A121] 00:00:00.000 (I) (config) hwaas : 5
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : false
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_3
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
[A121] 00:00:00.000 (I) (config) subsweep: 2
[A121] 00:00:00.000 (I) (config) start_point : 0
[A121] 00:00:00.000 (I) (config) num_points : 220
[A121] 00:00:00.000 (I) (config) step_length : 1
[A121] 00:00:00.000 (I) (config) hwaas : 7
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : false
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_5
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
[A121] 00:00:00.000 (I) (config) subsweep: 3
[A121] 00:00:00.000 (I) (config) start_point : 0
[A121] 00:00:00.000 (I) (config) num_points : 220
[A121] 00:00:00.000 (I) (config) step_length : 1
[A121] 00:00:00.000 (I) (config) hwaas : 15
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : false
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_5
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
[A121] 00:00:00.000 (I) (detector_distance) Far Sensor
[A121] 00:00:00.000 (I) (config) sweep_rate: 0.000000
[A121] 00:00:00.000 (I) (config) frame_rate: 0.000000
[A121] 00:00:00.000 (I) (config) sweeps_per_frame: 1
[A121] 00:00:00.000 (I) (config) continuous_sweep_mode: false
[A121] 00:00:00.000 (I) (config) double_buffering: false
[A121] 00:00:00.000 (I) (config) inter_frame_idle_state: DEEP_SLEEP
[A121] 00:00:00.000 (I) (config) inter_sweep_idle_state: READY
[A121] 00:00:00.000 (I) (config) num_subsweeps: 4
[A121] 00:00:00.000 (I) (config) subsweep: 0
[A121] 00:00:00.000 (I) (config) start_point : 48
[A121] 00:00:00.000 (I) (config) num_points : 87
[A121] 00:00:00.000 (I) (config) step_length : 4
[A121] 00:00:00.000 (I) (config) hwaas : 2
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : true
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_1
[A121] 00:00:00.000 (I) (config) profile : 19.5MHz
[A121] 00:00:00.000 (I) (config) subsweep: 1
[A121] 00:00:00.000 (I) (config) start_point : 120
[A121] 00:00:00.000 (I) (config) num_points : 68
[A121] 00:00:00.000 (I) (config) step_length : 12
[A121] 00:00:00.000 (I) (config) hwaas : 5
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : true
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_3
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
[A121] 00:00:00.000 (I) (config) subsweep: 2
[A121] 00:00:00.000 (I) (config) start_point : 264
[A121] 00:00:00.000 (I) (config) num_points : 30
[A121] 00:00:00.000 (I) (config) step_length : 24
[A121] 00:00:00.000 (I) (config) hwaas : 7
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : true
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_5
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
[A121] 00:00:00.000 (I) (config) subsweep: 3
[A121] 00:00:00.000 (I) (config) start_point : 984
[A121] 00:00:00.000 (I) (config) num_points : 25
[A121] 00:00:00.000 (I) (config) step_length : 24
[A121] 00:00:00.000 (I) (config) hwaas : 15
[A121] 00:00:00.000 (I) (config) receiver_gain : 10
[A121] 00:00:00.000 (I) (config) enable_tx : true
[A121] 00:00:00.000 (I) (config) phase_enhancement: true
[A121] 00:00:00.000 (I) (config) enable_loopback : false
[A121] 00:00:00.000 (I) (config) prf : PROFILE_5
[A121] 00:00:00.000 (I) (config) profile : 15.6MHz
输出多个目标点时 直接在后面进行打印：
附录：Cortex-M架构的SysTick系统定时器精准延时和MCU位带操作
SysTick系统定时器精准延时
延时函数
SysTick->LOAD中的值为计数值
计算方法为工作频率值/分频值
比如工作频率/1000 则周期为1ms
以ADuCM4050为例：
#include "ADuCM4050.h"void delay_ms(unsigned int ms)
{SysTick->LOAD = 26000000/1000-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能52MHz的系统定时器while(ms--){while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待}SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
void delay_us(unsigned int us)
{SysTick->LOAD = 26000000/1000/1000-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能52MHz的系统定时器while(us--){while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待}SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}其中的52000000表示芯片的系统定时器频率 32系列一般为外部定时器频率的两倍
Cortex-M架构SysTick系统定时器阻塞和非阻塞延时
阻塞延时
首先是最常用的阻塞延时
void delay_ms(unsigned int ms)
{SysTick->LOAD = 50000000/1000-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器while(ms--){while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待}SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
void delay_us(unsigned int us)
{SysTick->LOAD = 50000000/1000/1000-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器while(us--){while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待}SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
50000000表示工作频率
分频后即可得到不同的延时时间
以此类推
那么 不用两个嵌套while循环 也可以写成：
void delay_ms(unsigned int ms)
{SysTick->LOAD = 50000000/1000*ms-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
void delay_us(unsigned int us)
{SysTick->LOAD = 50000000/1000/1000*us-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
但是这种写法有个弊端
那就是输入ms后，最大定时不得超过计数值，也就是不能超过LOAD的最大值，否则溢出以后，则无法正常工作
而LOAD如果最大是32位 也就是4294967295
晶振为50M的话 50M的计数值为1s 4294967295计数值约为85s
固最大定时时间为85s
但用嵌套while的话 最大可以支持定时4294967295*85s
非阻塞延时
如果采用非阻塞的话 直接改写第二种方法就好了：
void delay_ms(unsigned int ms)
{SysTick->LOAD = 50000000/1000*ms-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器//while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待//SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
void delay_us(unsigned int us)
{SysTick->LOAD = 50000000/1000/1000*us-1; // Count from 255 to 0 (256 cycles) 载入计数值 定时器从这个值开始计数SysTick->VAL = 0; // Clear current value as well as count flag 清空计数值到达0后的标记SysTick->CTRL = 5; // Enable SysTick timer with processor clock 使能26MHz的系统定时器//while ((SysTick->CTRL & 0x00010000)==0);// Wait until count flag is set 等待//SysTick->CTRL = 0; // Disable SysTick 关闭系统定时器
}
将等待和关闭定时器语句去掉
在使用时加上判断即可变为阻塞：
delay_ms(500);
while ((SysTick->CTRL & 0x00010000)==0);
SysTick->CTRL = 0;
在非阻塞状态下 可以提交定时器后 去做别的事情 然后再来等待
不过这样又有一个弊端 那就是定时器会自动重载 可能做别的事情以后 定时器跑过了 然后就要等85s才能停下
故可以通过内部定时器来进行非阻塞延时函数的编写
基本上每个mcu的内部定时器都可以配置自动重载等功能 网上资料很多 这里就不再阐述了
位带操作
位带代码
M3、M4架构的单片机 其输出口地址为端口地址+20 输入为+16
M0架构的单片机 其输出口地址为端口地址+12 输入为+8
以ADuCM4050为列：
位带宏定义
#ifndef __GPIO_H__
#define __GPIO_H__
#include "ADuCM4050.h"
#include "adi_gpio.h"#define BITBAND(addr, bitnum) ((addr & 0xF0000000)+0x2000000+((addr &0xFFFFF)<<5)+(bitnum<<2))
#define MEM_ADDR(addr) *((volatile unsigned long *)(addr))
#define BIT_ADDR(addr, bitnum) MEM_ADDR(BITBAND(addr, bitnum))#define GPIO0_ODR_Addr (ADI_GPIO0_BASE+20) //0x40020014
#define GPIO0_IDR_Addr (ADI_GPIO0_BASE+16) //0x40020010#define GPIO1_ODR_Addr (ADI_GPIO1_BASE+20) //0x40020054
#define GPIO1_IDR_Addr (ADI_GPIO1_BASE+16) //0x40020050#define GPIO2_ODR_Addr (ADI_GPIO2_BASE+20) //0x40020094
#define GPIO2_IDR_Addr (ADI_GPIO2_BASE+16) //0x40020090#define GPIO3_ODR_Addr (ADI_GPIO3_BASE+20) //0x400200D4
#define GPIO3_IDR_Addr (ADI_GPIO3_BASE+16) //0x400200D0#define P0_O(n) BIT_ADDR(GPIO0_ODR_Addr,n) //输出
#define P0_I(n) BIT_ADDR(GPIO0_IDR_Addr,n) //输入 #define P1_O(n) BIT_ADDR(GPIO1_ODR_Addr,n) //输出
#define P1_I(n) BIT_ADDR(GPIO1_IDR_Addr,n) //输入 #define P2_O(n) BIT_ADDR(GPIO2_ODR_Addr,n) //输出
#define P2_I(n) BIT_ADDR(GPIO2_IDR_Addr,n) //输入 #define P3_O(n) BIT_ADDR(GPIO3_ODR_Addr,n) //输出
#define P3_I(n) BIT_ADDR(GPIO3_IDR_Addr,n) //输入 #define Port0 (ADI_GPIO_PORT0)
#define Port1 (ADI_GPIO_PORT1)
#define Port2 (ADI_GPIO_PORT2)
#define Port3 (ADI_GPIO_PORT3)#define Pin0 (ADI_GPIO_PIN_0)
#define Pin1 (ADI_GPIO_PIN_1)
#define Pin2 (ADI_GPIO_PIN_2)
#define Pin3 (ADI_GPIO_PIN_3)
#define Pin4 (ADI_GPIO_PIN_4)
#define Pin5 (ADI_GPIO_PIN_5)
#define Pin6 (ADI_GPIO_PIN_6)
#define Pin7 (ADI_GPIO_PIN_7)
#define Pin8 (ADI_GPIO_PIN_8)
#define Pin9 (ADI_GPIO_PIN_9)
#define Pin10 (ADI_GPIO_PIN_10)
#define Pin11 (ADI_GPIO_PIN_11)
#define Pin12 (ADI_GPIO_PIN_12)
#define Pin13 (ADI_GPIO_PIN_13)
#define Pin14 (ADI_GPIO_PIN_14)
#define Pin15 (ADI_GPIO_PIN_15)void GPIO_OUT(unsigned int port,unsigned int pin,unsigned int flag);
void GPIO_BUS_OUT(unsigned int port,unsigned int num);void P0_BUS_O(unsigned int num);
unsigned int P0_BUS_I(void);void P1_BUS_O(unsigned int num);
unsigned int P1_BUS_I(void);void P2_BUS_O(unsigned int num);
unsigned int P2_BUS_I(void);void P3_BUS_O(unsigned int num);
unsigned int P3_BUS_I(void);#endif总线函数
#include "ADuCM4050.h"
#include "adi_gpio.h"
#include "GPIO.h"void GPIO_OUT(unsigned int port,unsigned int pin,unsigned int flag)
{switch(port){case 0:{switch(pin){case 0:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_0));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_0));};break;case 1:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_1));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_1));};break;case 2:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_2));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_2));};break;case 3:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_3));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_3));};break;case 4:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_4));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_4));};break;case 5:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_5));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_5));};break;case 6:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_6));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_6));};break;case 7:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_7));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_7));};break;case 8:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_8));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_8));};break;case 9:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_9));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_9));};break;case 10:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_10));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_10));};break;case 11:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_11));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_11));};break;case 12:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_12));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_12));};break;case 13:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_13));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_13));};break;case 14:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_14));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_14));};break;case 15:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT0),(ADI_GPIO_PIN_15));}else{adi_gpio_SetLow((ADI_GPIO_PORT0),(ADI_GPIO_PIN_15));};break;default:pin=0;break;}}break;case 1:{switch(pin){case 0:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_0));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_0));};break;case 1:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_1));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_1));};break;case 2:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_2));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_2));};break;case 3:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_3));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_3));};break;case 4:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_4));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_4));};break;case 5:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_5));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_5));};break;case 6:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_6));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_6));};break;case 7:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_7));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_7));};break;case 8:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_8));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_8));};break;case 9:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_9));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_9));};break;case 10:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_10));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_10));};break;case 11:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_11));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_11));};break;case 12:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_12));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_12));};break;case 13:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_13));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_13));};break;case 14:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_14));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_14));};break;case 15:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT1),(ADI_GPIO_PIN_15));}else{adi_gpio_SetLow((ADI_GPIO_PORT1),(ADI_GPIO_PIN_15));};break;default:pin=0;break;}}break;case 2:{switch(pin){case 0:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_0));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_0));};break;case 1:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_1));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_1));};break;case 2:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_2));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_2));};break;case 3:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_3));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_3));};break;case 4:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_4));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_4));};break;case 5:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_5));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_5));};break;case 6:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_6));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_6));};break;case 7:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_7));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_7));};break;case 8:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_8));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_8));};break;case 9:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_9));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_9));};break;case 10:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_10));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_10));};break;case 11:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_11));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_11));};break;case 12:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_12));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_12));};break;case 13:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_13));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_13));};break;case 14:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_14));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_14));};break;case 15:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT2),(ADI_GPIO_PIN_15));}else{adi_gpio_SetLow((ADI_GPIO_PORT2),(ADI_GPIO_PIN_15));};break;default:pin=0;break;}}break;case 3:{switch(pin){case 0:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_0));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_0));};break;case 1:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_1));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_1));};break;case 2:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_2));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_2));};break;case 3:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_3));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_3));};break;case 4:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_4));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_4));};break;case 5:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_5));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_5));};break;case 6:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_6));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_6));};break;case 7:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_7));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_7));};break;case 8:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_8));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_8));};break;case 9:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_9));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_9));};break;case 10:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_10));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_10));};break;case 11:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_11));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_11));};break;case 12:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_12));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_12));};break;case 13:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_13));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_13));};break;case 14:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_14));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_14));};break;case 15:if(flag==1){adi_gpio_SetHigh((ADI_GPIO_PORT3),(ADI_GPIO_PIN_15));}else{adi_gpio_SetLow((ADI_GPIO_PORT3),(ADI_GPIO_PIN_15));};break;default:pin=0;break;}}break;default:port=0;break;}
}void GPIO_BUS_OUT(unsigned int port,unsigned int num) //num最大为0xffff
{int i;for(i=0;i<16;i++){GPIO_OUT(port,i,(num>>i)&0x0001);}
}void P0_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){P0_O(i)=(num>>i)&0x0001;}
}
unsigned int P0_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(P0_I(i)<<i)&0xFFFF;}return num;
}void P1_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){P1_O(i)=(num>>i)&0x0001;}
}
unsigned int P1_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(P1_I(i)<<i)&0xFFFF;}return num;
}void P2_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){P2_O(i)=(num>>i)&0x0001;}
}
unsigned int P2_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(P2_I(i)<<i)&0xFFFF;}return num;
}void P3_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){P3_O(i)=(num>>i)&0x0001;}
}
unsigned int P3_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(P3_I(i)<<i)&0xFFFF;}return num;
}一、位带操作理论及实践
位带操作的概念其实30年前就有了，那还是 CM3 将此能力进化，这里的位带操作是 8051 位寻址区的威力大幅加强版
位带区： 支持位带操作的地址区
位带别名： 对别名地址的访问最终作 用到位带区的访问上（注意：这中途有一个 地址映射过程）
位带操作对于硬件 I/O 密集型的底层程序最有用处
支持了位带操作后，可以使用普通的加载/存储指令来对单一的比特进行读写。在CM4中，有两个区中实现了位带。其中一个是SRAM区的最低1MB范围，第二个则是片内外设区的最低1MB范围。这两个区中的地址除了可以像普通的RAM一样使用外，它们还都有自己的“位带别名区”，位带别名区把每个比特膨胀成一个32位的字。当你通过位带别名区访问这些字时，就可以达到访问原始比特的目的。
位操作就是可以单独的对一个比特位读和写，类似与51中sbit定义的变量，stm32中通过访问位带别名区来实现位操作的功能
STM32中有两个地方实现了位带，一个是SRAM，一个是片上外设。
（1）位带本质上是一块地址区（例如每一位地址位对应一个寄存器）映射到另一片地址区（实现每一位地址位对应一个寄存器中的一位），该区域就叫做位带别名区，将每一位膨胀成一个32位的字。
（2）位带区的4个字节对应实际寄存器或内存区的一个位，虽然变大到4个字节，但实际上只有最低位有效（代表0或1）
只有位带可以直接用=赋值的方式来操作寄存器 位带是把寄存器上的每一位 膨胀到32位 映射到位带区 比如0x4002 0000地址的第0个bit 映射到位带区的0地址 那么其对应的位带映射地址为0x00 - 0x04 一共32位 但只有LSB有效 采用位带的方式用=赋值时 就是把位带区对应的LSB赋值 然后MCU再转到寄存器对应的位里面 寄存器操作时 如果不改变其他位上面的值 那就只能通过&=或者|=的方式进行
要设置0x2000 0000这个字节的第二个位bit2为1,使用位带操作的步骤有：
1、将1写入位 带别名区对应的映射地址（即0x22000008,因为1bit对应4个byte）；
2、将0x2000 0000的值 读取到内部的缓冲区（这一步骤是内核完成的，属于原子操作，不需要用户操作）；
3、将bit2置1，再把值写 回到0x2000 0000(属于原子操作，不需要用户操作)。
关于GPIO引脚对应的访问地址，可以参考以下公式
寄存器位带别名 = 0x42000000 + (寄存器的地址-0x40000000)32 + 引脚编号4
如：端口F访问的起始地址GPIOF_BASE
#define GPIOF ((GPIO_TypeDef *)GPIOF_BASE)
但好在官方库里面都帮我们定义好了 只需要在BASE地址加上便宜即可
例如：
GPIOF的ODR寄存器的地址 = GPIOF_BASE + 0x14
寄存器位带别名 = 0x42000000 + (寄存器的地址-0x40000000)32 + 引脚编号4
设置PF9引脚的话：
uint32_t *PF9_BitBand =
*(uint32_t *)(0x42000000 + ((uint32_t )&GPIOF->ODR– 0x40000000) *32 + 9*4)封装一下：
#define PFout(x) *(volatile uint32_t *)(0x42000000 + ((uint32_t )&GPIOF->ODR – 0x40000000) *32 + x*4)现在 可以把通用部分封装成一个小定义：
#define BITBAND(addr, bitnum) ((addr & 0xF0000000)+0x2000000+((addr &0xFFFFF)<<5)+(bitnum<<2))
#define MEM_ADDR(addr) *((volatile unsigned long *)(addr))
#define BIT_ADDR(addr, bitnum) MEM_ADDR(BITBAND(addr, bitnum))
那么 设置PF引脚的函数可以定义：
#define GPIOF_ODR_Addr (GPIOF_BASE+20) //0x40021414
#define GPIOF_IDR_Addr (GPIOF_BASE+16) //0x40021410 #define PF_O(n) BIT_ADDR(GPIOF_ODR_Addr,n) //输出
#define PF_I(n) BIT_ADDR(GPIOF_IDR_Addr,n) //输入
若使PF9输入输出则：
PF_O(9)=1; //输出高电平
uint8_t dat = PF_I(9); //获取PF9引脚的值
总线输入输出：
void PF_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PF_O(i)=(num>>i)&0x0001;}
}
unsigned int PF_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PF_I(i)<<i)&0xFFFF;}return num;
}
STM32的可用下面的函数：
#ifndef __GPIO_H__
#define __GPIO_H__
#include "stm32l496xx.h"#define BITBAND(addr, bitnum) ((addr & 0xF0000000)+0x2000000+((addr &0xFFFFF)<<5)+(bitnum<<2))
#define MEM_ADDR(addr) *((volatile unsigned long *)(addr))
#define BIT_ADDR(addr, bitnum) MEM_ADDR(BITBAND(addr, bitnum))#define GPIOA_ODR_Addr (GPIOA_BASE+20) //0x40020014
#define GPIOB_ODR_Addr (GPIOB_BASE+20) //0x40020414
#define GPIOC_ODR_Addr (GPIOC_BASE+20) //0x40020814
#define GPIOD_ODR_Addr (GPIOD_BASE+20) //0x40020C14
#define GPIOE_ODR_Addr (GPIOE_BASE+20) //0x40021014
#define GPIOF_ODR_Addr (GPIOF_BASE+20) //0x40021414
#define GPIOG_ODR_Addr (GPIOG_BASE+20) //0x40021814
#define GPIOH_ODR_Addr (GPIOH_BASE+20) //0x40021C14
#define GPIOI_ODR_Addr (GPIOI_BASE+20) //0x40022014 #define GPIOA_IDR_Addr (GPIOA_BASE+16) //0x40020010
#define GPIOB_IDR_Addr (GPIOB_BASE+16) //0x40020410
#define GPIOC_IDR_Addr (GPIOC_BASE+16) //0x40020810
#define GPIOD_IDR_Addr (GPIOD_BASE+16) //0x40020C10
#define GPIOE_IDR_Addr (GPIOE_BASE+16) //0x40021010
#define GPIOF_IDR_Addr (GPIOF_BASE+16) //0x40021410
#define GPIOG_IDR_Addr (GPIOG_BASE+16) //0x40021810
#define GPIOH_IDR_Addr (GPIOH_BASE+16) //0x40021C10
#define GPIOI_IDR_Addr (GPIOI_BASE+16) //0x40022010 #define PA_O(n) BIT_ADDR(GPIOA_ODR_Addr,n) //输出
#define PA_I(n) BIT_ADDR(GPIOA_IDR_Addr,n) //输入 #define PB_O(n) BIT_ADDR(GPIOB_ODR_Addr,n) //输出
#define PB_I(n) BIT_ADDR(GPIOB_IDR_Addr,n) //输入 #define PC_O(n) BIT_ADDR(GPIOC_ODR_Addr,n) //输出
#define PC_I(n) BIT_ADDR(GPIOC_IDR_Addr,n) //输入 #define PD_O(n) BIT_ADDR(GPIOD_ODR_Addr,n) //输出
#define PD_I(n) BIT_ADDR(GPIOD_IDR_Addr,n) //输入 #define PE_O(n) BIT_ADDR(GPIOE_ODR_Addr,n) //输出
#define PE_I(n) BIT_ADDR(GPIOE_IDR_Addr,n) //输入#define PF_O(n) BIT_ADDR(GPIOF_ODR_Addr,n) //输出
#define PF_I(n) BIT_ADDR(GPIOF_IDR_Addr,n) //输入#define PG_O(n) BIT_ADDR(GPIOG_ODR_Addr,n) //输出
#define PG_I(n) BIT_ADDR(GPIOG_IDR_Addr,n) //输入#define PH_O(n) BIT_ADDR(GPIOH_ODR_Addr,n) //输出
#define PH_I(n) BIT_ADDR(GPIOH_IDR_Addr,n) //输入#define PI_O(n) BIT_ADDR(GPIOI_ODR_Addr,n) //输出
#define PI_I(n) BIT_ADDR(GPIOI_IDR_Addr,n) //输入void PA_BUS_O(unsigned int num);
unsigned int PA_BUS_I(void);void PB_BUS_O(unsigned int num);
unsigned int PB_BUS_I(void);void PC_BUS_O(unsigned int num);
unsigned int PC_BUS_I(void);void PD_BUS_O(unsigned int num);
unsigned int PD_BUS_I(void);void PE_BUS_O(unsigned int num);
unsigned int PE_BUS_I(void);void PF_BUS_O(unsigned int num);
unsigned int PF_BUS_I(void);void PG_BUS_O(unsigned int num);
unsigned int PG_BUS_I(void);void PH_BUS_O(unsigned int num);
unsigned int PH_BUS_I(void);void PI_BUS_O(unsigned int num);
unsigned int PI_BUS_I(void);#endif#include "GPIO.h"void PA_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PA_O(i)=(num>>i)&0x0001;}
}
unsigned int PA_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PA_I(i)<<i)&0xFFFF;}return num;
}void PB_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PB_O(i)=(num>>i)&0x0001;}
}
unsigned int PB_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PB_I(i)<<i)&0xFFFF;}return num;
}void PC_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PC_O(i)=(num>>i)&0x0001;}
}
unsigned int PC_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PC_I(i)<<i)&0xFFFF;}return num;
}void PD_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PD_O(i)=(num>>i)&0x0001;}
}
unsigned int PD_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PD_I(i)<<i)&0xFFFF;}return num;
}void PE_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PE_O(i)=(num>>i)&0x0001;}
}
unsigned int PE_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PE_I(i)<<i)&0xFFFF;}return num;
}void PF_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PF_O(i)=(num>>i)&0x0001;}
}
unsigned int PF_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PF_I(i)<<i)&0xFFFF;}return num;
}void PG_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PG_O(i)=(num>>i)&0x0001;}
}
unsigned int PG_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PG_I(i)<<i)&0xFFFF;}return num;
}void PH_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PH_O(i)=(num>>i)&0x0001;}
}
unsigned int PH_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PH_I(i)<<i)&0xFFFF;}return num;
}void PI_BUS_O(unsigned int num) //输入值num最大为0xFFFF
{int i;for(i=0;i<16;i++){PI_O(i)=(num>>i)&0x0001;}
}
unsigned int PI_BUS_I(void) //输出值num最大为0xFFFF
{unsigned int num;int i;for(i=0;i<16;i++){num=num+(PI_I(i)<<i)&0xFFFF;}return num;
}二、如何判断MCU的外设是否支持位带
根据《ARM Cortex-M3与Cortex-M4权威指南(第3版)》中第6章第7节描述
也就是说 要实现对GPIO的位带操作 必须保证GPIO位于外设区域的第一个1MB中
第一个1MB应该是0x4010 0000之前 位带不是直接操作地址 而是操作地址映射 地址映射被操作以后 MCU自动会修改对应寄存器的值
位带区只有1MB 所以只能改0x4000 0000 - 0x400F FFFF的寄存器
像F4系列 GPIO的首地址为0x4002 0000 就可以用位带来更改
STM32L476的GPIO就不行：
AHB2的都不能用位带
ABP 还有AHB1都可以用
但是L476的寄存器里面 GPIO和ADC都是AHB2
