【AT-START-F403A测评】之七freeRTOS系统基于IAR弹性DMA定量输出PWM脉冲评测
本帖最后由 uuxz99 于 2020-11-9 07:47 编辑<p><b><span style="font-size:14.0pt"><span style="background:white"><span style="font-family:"微软雅黑","sans-serif""><span style="color:#444444"><span style="letter-spacing:.75pt">【</span></span></span></span></span><span lang="EN-US" style="font-size:14.0pt"><span style="background:white"><span style="font-family:"微软雅黑","sans-serif""><span style="color:#444444"><span style="letter-spacing:.75pt">AT-START-F403A</span></span></span></span></span><span style="font-size:14.0pt"><span style="background:white"><span style="font-family:"微软雅黑","sans-serif""><span style="color:#444444"><span style="letter-spacing:.75pt">测评】</span></span></span></span></span><span style="font-size:14.0pt"><span style="background:white"><span style="font-family:"微软雅黑","sans-serif""><span style="color:#333333">之七freeRTOS系统基于IAR弹性DMA定量输出PWM脉冲评测</span></span></span></span></b></p>
<p><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">本次测评在之前建立的安全库项目中实现，通过弹性DMA实现定量化PWM脉冲输出，实现了系统控制最后一公里的目标，为后续在slib中实现有关PWM参数生成算法打下基础。此次评测使用定时器TMR1_CH1和TMR4_CH2，作为两路PWM输出端口。输出频率均为1KHz，占空比50%。以下为评测过程。</span></span></p>
<p style="margin-left:28px; text-align:justify"><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><b><span lang="EN-US" style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">1.</span></span></b><b><span style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">串口DMA通道升级</span></span></b></span></span></span></p>
<p align="left" style="text-align:left; text-indent:33.0pt"><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">在以前评测中采用了固定DMA通道的方式，为了不再为DMA通道资源分配而烦恼，更改采用DMA的弹性通道机制。</span></span></span></span></span></p>
<p align="left" style="text-align:left; text-indent:33.0pt"><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><b><span lang="EN-US" style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">2. </span></span></b><b><span style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">定时器配置</span></span></b></span></span></span></p>
<ol>
<li style="list-style-type:none"> </li>
</ol>
<p style="text-align:left"><span style="font-size:10.5pt"><span style="font-family:Calibri,sans-serif"><span lang="EN-US" style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">2.1 GPIO</span></span><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">配置</span></span></span></span></p>
<p>2.2 <span style="font-size:10.5pt"><span style="font-family:Calibri,sans-serif"><span lang="EN-US" style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">dma</span></span><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">配置</span></span></span></span></p>
<p>2.3 tmr配置</p>
<p>2.4 <span style="font-size:10.5pt"><span style="font-family:Calibri,sans-serif"><span lang="EN-US" style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">PWM</span></span><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">功能整体实现</span></span></span></span></p>
<p></p>
<p><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><b><span lang="EN-US" style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">3.</span></span></b><b><span style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">在任务中测试</span></span></b></span></span></span></p>
<p><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">改写之前点亮红色led任务作为控制定量脉冲输出任务，两个定时器各自每次定量输出和10个和5个脉冲。</span></span></span></span></span></p>
<p><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><b><span lang="EN-US" style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">4.</span></span></b><b><span style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif"">结论</span></span></b></span></span></span></p>
<p><span style="font-size:10.5pt"><span style="layout-grid-mode:char"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="font-family:"微软雅黑","sans-serif"">通过灵活的弹性DMA机制，提高了DMA外围设备的利用率，节省了大量CPU时间，大量精力集中于应用实现。本测评通过调整DMA数据传送方式可实现频率和占空比可变。</span></span></span></span></span><b><span lang="EN-US" style="font-size:14.0pt"><span style="font-family:"微软雅黑","sans-serif""> </span></span></b></p>
<p> </p>
<p align="left" style="text-align:left; text-indent:33.0pt"> </p>
<p>好久没用IAR了，我也申请了这个板子，先参考一下哈。</p>
这个板子居然申请到了，不容易 <p>dma输出pwm?呃，学习一下、</p>
freebsder 发表于 2020-11-9 23:01
dma输出pwm?呃，学习一下、
<p>dma传输两个数字，一个字节就是on时间，另一个字节就是off时间，每两个字节确定一个pwm周期。呼吸灯实现就是把所有周期都做成一个表让dma一个接一个送，基本就是这个实现原理</p>
uuxz99 发表于 2020-11-11 20:11
dma传输两个数字，一个字节就是on时间，另一个字节就是off时间，每两个字节确定一个pwm周期。呼吸灯实现 ...
<p>没用过dma搞pwm，，，感觉很神奇。</p>
页:
[1]