¶ Preface
SARADC is a 6-channel 10-bit effective digital-to-analog converter. When the input frequency is 13MHz, the conversion speed is 1MSPS.
¶ adc pin
Hot Wheels Technology has developed a rk3588s motherboard, youyeetoo R1, which provides 40pin expansion pins, including 1 CAN pin. The pin distribution is shown in the figure below:
¶ shell command call
If you want to use shell commands in the Android system, you need to enter the Android command line window through ADB. For tutorials on using ADB, please refer to the adb debugging chapter. After opening the Android system command line through adb,
cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
¶ Android NDK call
The complete app is available here
- adc demo
Official Download
http://dd.youyeetoo.cn:5000/sharing/NmqPRhHyz
Google Download
https://drive.google.com/drive/folders/1D-uZn-BxQMwFJv3OGdAKW0HEXU-2zpJT?usp=drive_link
The permission management of the Android system is very strict. Using c++ or java to operate files or resources in the Android root file system requires corresponding permissions. The ndk program written here is written based on the system app as a template. For system app, please refer to the chapter Creating system app.
#include <jni.h>
#include <string>
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <linux/i2c.h>
#include <android/log.h>
#define LOG_TAG "R1-AdcTest"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
#define ADC_DEVICE "/sys/bus/iio/devices/iio\:device0/in_voltage4_raw"
extern "C" JNIEXPORT jstring JNICALL
Java_com_youyeetoo_r1_1adcdemo_MainActivity_stringFromJNI(
JNIEnv* env,
jobject /* this */) {
std::string hello = "Hello from C++";
FILE *fd=NULL;
char adc_value[5];
char show_buf[48];
float Voltage;
int tmp;
fd=fopen(ADC_DEVICE,"r");
if (fd == NULL){
return env->NewStringUTF("open ADC_DEVICE failed \n");
}
fscanf(fd,"%s",adc_value);
fclose(fd);
sscanf(adc_value, "%d", &tmp);
Voltage = tmp / 4096.0 * 1.8;
sprintf(show_buf, "adc value: %s Voltage: %f",adc_value, Voltage);
return env->NewStringUTF(show_buf);
}