【FRDM-MCXN947测评】DAC数模转换测试
<p><strong>1、测试介绍</strong></p><p>MCXN947VDF MCU有两组DAC通道，12bit 2个，14bit 1个本次使用测试的是DAC0通道，测试通过中断进行设置操作，通过串口进行修改测试电压值的操作。</p>
<p>硬件：FRDM-MCXN947开发板，万用表。</p>
<p>软件：GCC ARM Embedded 13.2.1编译器。不知道这个编译器版本是绑定的，在VScode中无法更换。</p>
<p> Putty串口终端软件。</p>
<p> 通过J1接口的4_2pin输出。 </p>
<p> </p>
<p><strong>2、测试过程</strong></p>
<p>程序项目参考dac_1_buffer_interrupt样例</p>
<p>使用vscode打开项目</p>
<p> 使用Putty软件连接串口。</p>
<p> </p>
<p>通过putty终端进行修改电压值</p>
<p> 电压最低值：0.0095，最高值：2.484，输出基本上稳定。</p>
<p><strong>3、软件设计</strong></p>
<p>软件步骤：</p>
<p>1、初始化DAC设备</p>
<p>2、启动DAC设备</p>
<p>3、启动DAC中断</p>
<pre>
<code class="language-cpp">/*
* Copyright (c) 2016, Freescale Semiconductor, Inc.
* Copyright 2016-2017 NXP
* All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "fsl_debug_console.h"
#include "pin_mux.h"
#include "clock_config.h"
#include "board.h"
#include "fsl_dac.h"
/*******************************************************************************
* Definitions
******************************************************************************/
#define DEMO_DAC_BASEADDR DAC0
#define DEMO_DAC_IRQ_ID DAC0_IRQn
#define DEMO_DAC_IRQ_HANDLER_FUNC DAC0_IRQHandler
#define DEMO_DAC_VREF kDAC_ReferenceVoltageSourceAlt1
#define DEMO_DAC_VALUE_ARRAY_SIZE 32U
/*******************************************************************************
* Prototypes
******************************************************************************/
/*******************************************************************************
* Variables
******************************************************************************/
volatile uint32_t g_DacInputIndex = 0U;
volatile uint32_t g_DacOutputIndex = 0U;
volatile uint32_t g_DacInterruptDone = false;
/* User-defined wave for DAC output. */
const uint32_t g_DacValues = {
0U, 100,200,300,400,500,600,700,800,900,1000, 1100, 1200, 1300, 1400, 1500,
1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100};
/*******************************************************************************
* Code
******************************************************************************/
/*!
* @brief Main function
*/
int main(void)
{
dac_config_t dacConfigStruct;
/* attach FRO 12M to FLEXCOMM4 (debug console) */
CLOCK_SetClkDiv(kCLOCK_DivFlexcom4Clk, 1u);
CLOCK_AttachClk(BOARD_DEBUG_UART_CLK_ATTACH);
/* attach FRO HF to DAC0 */
CLOCK_SetClkDiv(kCLOCK_DivDac0Clk, 1u);
CLOCK_AttachClk(kFRO_HF_to_DAC0);
/* enable DAC0 and VREF */
SPC0->ACTIVE_CFG1 |= 0x11;
BOARD_InitPins();
BOARD_InitBootClocks();
BOARD_InitDebugConsole();
EnableIRQ(DEMO_DAC_IRQ_ID); /* Enable interrupt in NVIC. */
PRINTF("\r\nDAC buffer interrupt Example.\r\n");
/* Configure the DAC. */
DAC_GetDefaultConfig(&dacConfigStruct);
dacConfigStruct.referenceVoltageSource = DEMO_DAC_VREF;
dacConfigStruct.fifoTriggerMode = kDAC_FIFOTriggerBySoftwareMode; /* Software trigger. */
dacConfigStruct.fifoWorkMode = kDAC_FIFOWorkAsNormalMode; /* Normal FIFO mode. */
dacConfigStruct.fifoWatermarkLevel = 4U; /* Watermark. */
DAC_Init(DEMO_DAC_BASEADDR, &dacConfigStruct);
DAC_Enable(DEMO_DAC_BASEADDR, true); /* Enable output. */
PRINTF("Press any key to trigger the DAC...\r\n");
/* Enable DAC interrupts. */
DAC_EnableInterrupts(DEMO_DAC_BASEADDR, kDAC_FIFOEmptyInterruptEnable);
while (1)
{
/* Wait*/
while (!g_DacInterruptDone)
{
}
g_DacInterruptDone = false;
/* Trigger the buffer and move the pointer. */
GETCHAR();
DAC_DoSoftwareTriggerFIFO(DEMO_DAC_BASEADDR);
PRINTF("DAC next output: %d\r\n", g_DacValues);
if (g_DacOutputIndex >= DEMO_DAC_VALUE_ARRAY_SIZE - 1U)
{
g_DacOutputIndex = 0U;
}
else
{
g_DacOutputIndex++;
}
}
}
/*!
* @brief IRQ function for DAC buffer interrupt
*/
void DEMO_DAC_IRQ_HANDLER_FUNC(void)
{
uint32_t flags = DAC_GetStatusFlags(DEMO_DAC_BASEADDR);
if (0U != (kDAC_FIFOEmptyFlag & flags))
{
DAC_SetData(DEMO_DAC_BASEADDR, g_DacValues);
if (g_DacInputIndex >= (DEMO_DAC_VALUE_ARRAY_SIZE - 1U))
{
g_DacInputIndex = 0U;
}
else
{
g_DacInputIndex++;
}
}
g_DacInterruptDone = true;
SDK_ISR_EXIT_BARRIER;
}
</code></pre>
<p>4、刷新DAC_DoSoftwareTriggerFIFO(DEMO_DAC_BASEADDR);输入输出堆列。</p>
<p>中断中修改value</p>
<pre>
<code class="language-cpp">/*!
* @brief IRQ function for DAC buffer interrupt
*/
void DEMO_DAC_IRQ_HANDLER_FUNC(void)
{
uint32_t flags = DAC_GetStatusFlags(DEMO_DAC_BASEADDR);
if (0U != (kDAC_FIFOEmptyFlag & flags))
{
DAC_SetData(DEMO_DAC_BASEADDR, g_DacValues);
if (g_DacInputIndex >= (DEMO_DAC_VALUE_ARRAY_SIZE - 1U))
{
g_DacInputIndex = 0U;
}
else
{
g_DacInputIndex++;
}
}
g_DacInterruptDone = true;
SDK_ISR_EXIT_BARRIER;
}
</code></pre>
<p>通过 DAC_SetData(DEMO_DAC_BASEADDR, g_DacValues);数组修改DAC的输出值。</p>
<p><strong>4、总结</strong></p>
<p>本次测试通过中断修改DAC的输出数值，当DAC完成输出后即使通过FIFO队列输出数据。NXP的DAC中断设计相当的完善，可以防止DAC输出出现间断的可能。</p>
<p> </p>
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