BearPi-HM_Nano开发板基础外设开发——ADC采样
本示例将演示如何在BearPi-HM_Nano开发板上通过按下按键改变GPIO口的电压，并使用ADC读取GPIO的电压值，
ADC API分析
本案例主要使用了以下API完成ADC采样的功能
IoTAdcRead()
/**
* @brief Reads a piece of sampled data from a specified ADC channel based on the input parameters.
*
*
*
* @param channel Indicates the ADC channel index.
* @param data Indicates the pointer to the address for storing the read data.
* @param equModel Indicates the equation model.
* @param curBais Indicates the analog power control mode.
* @param rstCnt Indicates the count of the time from reset to conversion start.
* One count is equal to 334 ns. The value must range from 0 to 0xFF0.
* @return Returns {@link IOT_SUCCESS} if the PWM signal output is stopped;
* returns {@link IOT_FAILURE} otherwise. For details about other return values, see the chip description.
* @since 1.0
* @version 1.0
*/
unsigned int IoTAdcRead(unsigned int channel, unsigned short *data, IotAdcEquModelSel equModel,
IotAdcCurBais curBais, unsigned short rstCnt);描述：
根据输入参数从指定的ADC通道读取一段采样数据
参数：
| 名字 | 描述 |
|---|---|
| channel | 表示ADC通道. |
| data | 表示指向存储读取数据的地址的指针 |
| equModel | 表示平均算法的次数 |
| curBais | 表示模拟功率控制模式 |
| rstCnt | 指示从重置到转换开始的时间计数。一次计数等于334纳秒。值的范围必须从0到0xFF |
硬件设计
本案例将使用板载用户按键F1来模拟GPIO口电压的变化。通过查看芯片手册可知GPIO_11对应的是 ADC Channel 5 ,所以需要编写软件去读取ADC Channel 5的电压,程序设计时先将GPIO_11上拉，使GPIO_11的电压一直处于高电平，当按键按下时GPIO_11接地，此时GPIO_11的电压变为 0 V。
软件设计
主要代码分析
该函数通过使用IoTAdcRead()函数来读取 ADC_CHANNEL_5 的数值存储在data中， IOT_ADC_EQU_MODEL_8 表示8次平均算法模式，IOT_ADC_CUR_BAIS_DEFAULT 表示默认的自动识别模式，最后通过 data * 1.8 * 4 / 4096.0 计算出实际的电压值。
yuchuan_basic_adc.c
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
#include "ohos_init.h"
#include "cmsis_os2.h"
#include "iot_gpio.h"
#include "iot_gpio_ex.h"
#include "iot_adc.h"
#include "iot_errno.h"
#define TASK_STACK_SIZE 1024 * 4
#define TASK_PRIORITY 24
#define BUTTON_F1_GPIO 11
#define ADC_CHANNEL_5 5
static float getVoltage(void)
{
unsigned int ret;
unsigned short data;
//ADC通道采样数据读取电压只
//unsigned int IoTAdcRead(unsigned int channel, unsigned short *data, IotAdcEquModelSel equModel,
// IotAdcCurBais curBais, unsigned short rstCnt);
ret = IoTAdcRead(ADC_CHANNEL_5, &data, IOT_ADC_EQU_MODEL_8, IOT_ADC_CUR_BAIS_DEFAULT, 0Xff);
if (ret != IOT_SUCCESS)
{
/* code */
printf("ADC Read Failed!!!\n");
}
return (float)data * 1.8 * 4 / 4096.0;
}
void yuchuanThreadADC(void *argument)
{
(void)argument;
float voltage;
//上拉，让按键为按下GPIO_11 保持高电平状态
IoTGpioSetPull(BUTTON_F1_GPIO,IOT_GPIO_PULL_UP);
while (1)
{
/* code */
printf("***************************************\r\n");
printf("************Yuchuan ADC Example********\r\n");
printf("***************************************\r\n");
//获取Button F1 的电压之
voltage = getVoltage();
printf("YuchuanThread get voltage is : %.3fV\n",voltage);
//延时1s
usleep(1000000);
}
}
static void yuchuanBasicADCExample(void)
{
osThreadAttr_t threadAttr;
threadAttr.attr_bits = 0U;
threadAttr.cb_mem = NULL;
threadAttr.cb_size = 0U;
threadAttr.stack_mem = NULL;
threadAttr.stack_size = TASK_STACK_SIZE;
threadAttr.priority = TASK_PRIORITY;
threadAttr.name = "YuchuanThreadADC";
if (osThreadNew((osThreadFunc_t)yuchuanThreadADC,NULL,&threadAttr) == NULL)
{
/* code */
printf("Falied to Create YuchuanThreadADC!!!\n");
}
}
APP_FEATURE_INIT(yuchuanBasicADCExample);编译调试
//applications/sample/BearPi/BearPi-HM_Nano/sample/B4_YuchuanBasicADC
static_library("yuchuanBasicADC"){
sources = [
"yuchuan_basic_adc.c",
]
include_dirs = [
"//utils/native/lite/include",
"//kernel/liteos_m/kal/cmsis",
"//base/iot_hardware/peripheral/interfaces/kits",
]
}修改 BUILD.gn 文件
修改applications\BearPi\BearPi-HM_Nano\sample 路径下 BUILD.gn 文件，指定 yuchuanBasicADC 参与编译。
# Copyright (c) 2020 Nanjing Xiaoxiongpai Intelligent Technology Co., Ltd.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import("//build/lite/config/component/lite_component.gni")
lite_component("sample") {
features = [
#"A1_kernal_thread:thread_example",
#"A2_kernel_timer:timer_example",
#"A3_kernel_event:event_example",
#"A4_kernel_mutex:mutex_example",
#"A5_kernel_semaphore:semaphore_example",
#"A6_kernel_message:message_example",
#"B1_basic_led_blink:led_example",
#"B2_basic_button:button_example",
#"B3_basic_pwm_led:pwm_example",
#"B4_basic_adc:adc_example",
#"B5_basic_i2c_nfc:i2c_example",
#"B6_basic_uart:uart_example",
#"C1_e53_sf1_mq2:e53_sf1_example",
#"C2_e53_ia1_temp_humi_pls:e53_ia1_example",
#"C3_e53_sc1_pls:e53_sc1_example",
#"C4_e53_sc2_axis:e53_sc2_example",
#"C5_e53_is1_infrared:e53_is1_example",
#"D1_iot_wifi_ap:wifi_ap",
#"D2_iot_wifi_sta_connect:wifi_sta_connect",
#"D3_iot_udp_client:udp_client",
#"D4_iot_tcp_server:tcp_server",
#"D5_iot_mqtt:iot_mqtt",
#"D6_iot_cloud_oc:oc_mqtt",
#"D7_iot_cloud_onenet:onenet_mqtt",
#"D8_iot_cloud_oc_smoke:cloud_oc_smoke",
#"D9_iot_cloud_oc_light:cloud_oc_light",
#"D10_iot_cloud_oc_manhole_cover:cloud_oc_manhole_cover",
#"D11_iot_cloud_oc_infrared:cloud_oc_infrared",
#"D12_iot_cloud_oc_agriculture:cloud_oc_agriculture",
#"D13_iot_cloud_oc_gps:cloud_oc_gps",
#"A1_YuchuanThread:yuchuanThread",
#"A2_YuchuanTimer:yuchuanTimer",
#"A4_YuchuanMutex:yuchuanMutex",
#"A5_YuchuanSemaphore:yuchuanSemaphore",
#"A3_YuchuanEvent:yuchuanEvent",
#"A6_YuchuanMessage:yuchuanMessageQueue",
#"B3_YuchuanBasicPWM:yuchuanPWM",
"B4_YuchuanBasicADC:yuchuanBasicADC",
]
}运行结果
示例代码编译烧录代码后，按下开发板的RESET按键，通过串口助手查看日志，当F1按键未按下时采集到的电压为3.3V左右，当按键按下时，电压变为0.2V左右。
ready to OS start
sdk ver:Hi3861V100R001C00SPC025 2020-09-03 18:10:00
formatting spiffs...
FileSystem mount ok.
wifi init success!
hiview init success.00 00:00:00 0 132 D 0/HIVIEW: log limit init success.
00 00:00:00 0 132 I 1/SAMGR: Bootstrap core services(count:3).
00 00:00:00 0 132 I 1/SAMGR: Init service:0x4b0128 TaskPool:0xe4b3c
00 00:00:00 0 132 I 1/SAMGR: Init service:0x4b0134 T***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.326V
askPool:0xe4b5c
00 00:00:00 0 132 I 1/SAMGR: Init service:0x4b0600 TaskPool:0xe4b7c
00 00:00:00 0 164 I 1/SAMGR: Init service 0x4b0134 <time: 0ms> success!
00 00:00:00 0 64 I 1/SAMGR: Init service 0x4b0128 <time: 0ms> success!
00 00:00:00 0 8 I 1/SAMGR: Init service 0x4b0600 <time: 0ms> success!
00 00:00:00 0 8 I 1/SAMGR: Initialized all core system services!
00 00:00:00 0 64 I 1/SAMGR: Bootstrap system and application services(count:0).
00 00:00:00 0 64 I 1/SAMGR: Initialized all system and application services!
00 00:00:00 0 64 I 1/SAMGR: Bootstrap dynamic registered services(count:0).
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.331V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.329V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.331V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.333V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.329V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.331V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 0.248V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 0.246V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 0.250V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 0.248V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.329V
***************************************
************Yuchuan ADC Example********
***************************************
YuchuanThread get voltage is : 3.329V
***************************************