【MCXA156开发板测评】-3-LPTMR体验
本帖最后由 慕容雪花 于 2025-1-10 07:04 编辑<p>MCXA156片上定时器外设可谓是非常丰富，有Standart Counter/Timers 即CTimer， 还有Windowed Watchdog Timer，Micro-Tick Timer， OS Event Timer，Wake Timer。</p>
<p>在NXP的论坛上，也找到了一些对不同种类的NXP片上定时器的介绍：<a href="https://community.nxp.com/t5/MCUXpresso-SDK/Timer-in-LPC546xx/m-p/1081234" target="_blank">链接</a></p>
<p>1)SCTimer/PWM: can generate complicated PWM signal to control even motor, have capture function, can generate interrupt with programmable interval, can be a frequency divider.</p>
<p>2)CTimer: can generate simple PWM signal, can generate interrupt with programmable interval, has capture function, can be a frequency divider.</p>
<p>3)Multi-Rate Timer (MRT): can only generate interrupt</p>
<p>4)Repetitive Interrupt Timer (RIT): can only generate interrupt</p>
<p>5)System tick timer (SYSTICK): can generate interrupt for core</p>
<p>6)Micro-tick Timer (UTICK): can generate interrupt, and have capture function</p>
<p> </p>
<p>本次体验一下使用NXP的工具全家桶MCUXPRESSO IDE配合内置的MCU CONFIG TOOL来快速制作一个1ms时基的中断服务程序，来闪烁小灯，串口输出。</p>
<p>首先点击使能LPTMR的时钟： </p>
<p> </p>
<p>点击IDE右上角的USB符号，进入到外设配置界面。</p>
<p> </p>
<p>之后可以输入LPTMR0进行搜索，添加该模块后，进入到配置界面，比如运行模式，频率，是否开启中断，是否要在初始化函数中启动LPTMR0等。</p>
<p>区别于别的IDE，在MCU ConfigTool里面还提供了ISR模板，可以点击“Copy to clipboard”来复制然后粘贴到自己对应用代码中。</p>
<p>如下所示即为添加了闪烁小灯与串口打印后的ISR。</p>
<pre>
<code>/* LPTMR0_IRQn interrupt handler */
void LPTMR0_IRQHANDLER(void) {
uint32_t intStatus;
/* Reading all interrupt flags of status register */
intStatus = LPTMR_GetStatusFlags(LPTMR0_PERIPHERAL);
LPTMR_ClearStatusFlags(LPTMR0_PERIPHERAL, intStatus);
/* Place your code here */
static uint32_t cnt = 0;
cnt++;
if(cnt%1000 == 0){
/* Toggle pin connected to LED */
GPIO_PortToggle(GPIO3, 1u << 0);
PRINTF("\r\n GPIO3_0 RED LED TOOGLED, cnt = %d", cnt);
}
/* Add for ARM errata 838869, affects Cortex-M4, Cortex-M4F
Store immediate overlapping exception return operation might vector to incorrect interrupt. */
#if defined __CORTEX_M && (__CORTEX_M == 4U)
__DSB();
#endif
}</code></pre>
<p>下面是IDE自动生成的LPTMR0的配置及初始化代码：</p>
<pre>
<code>const lptmr_config_t LPTMR0_config = {
.timerMode = kLPTMR_TimerModeTimeCounter,
.pinSelect = kLPTMR_PinSelectInput_0,
.pinPolarity = kLPTMR_PinPolarityActiveHigh,
.enableFreeRunning = false,
.bypassPrescaler = true,
.prescalerClockSource = kLPTMR_PrescalerClock_3,
.value = kLPTMR_Prescale_Glitch_0
};
static void LPTMR0_init(void) {
/* Initialize the LPTMR */
LPTMR_Init(LPTMR0_PERIPHERAL, &LPTMR0_config);
/* Set LPTMR period */
LPTMR_SetTimerPeriod(LPTMR0_PERIPHERAL, LPTMR0_TICKS);
/* Configure timer interrupt */
LPTMR_EnableInterrupts(LPTMR0_PERIPHERAL, kLPTMR_TimerInterruptEnable);
/* Interrupt vector LPTMR0_IRQn priority settings in the NVIC. */
NVIC_SetPriority(LPTMR0_IRQN, LPTMR0_IRQ_PRIORITY);
/* Enable interrupt LPTMR0_IRQN request in the NVIC */
EnableIRQ(LPTMR0_IRQN);
/* Start the LPTMR timer */
LPTMR_StartTimer(LPTMR0_PERIPHERAL);
}</code></pre>
<p>烧录，全速运行，看到串口大概1s输出一次。</p>
<p> </p>
<div style="text-align: center;"></div>
<p>换个带时间戳的串口助手，看的更细节：</p>
<p> </p>
<p>添加该模块后，进入到配置界面，然后的操作好像有点麻烦了</p>
Jacktang 发表于 2025-1-10 07:47
添加该模块后，进入到配置界面，然后的操作好像有点麻烦了
<p>确实，这个芯片的功能还是很强大的，也意味着更多的参数需要去了解，配置。</p>
谢谢分享，MUCXPressoIDE 配置外设还是非常方便的。
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