我的Wiegand RFID阅读器（26bit）有问题。我写了简单的Java应用程序，一切似乎都很好。但是在10次读取之后，它开始移位。对于Wiegand时间协议，RPi Raspbian是否会放慢速度？
以下是示例代码和输出
package classes;
import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalInput;
import com.pi4j.io.gpio.PinPullResistance;
import com.pi4j.io.gpio.RaspiPin;
public class Test {
public static char[] s = new char[10000];
static int bits = 0;
public static void main(String[] args) {
// create gpio controller
final GpioController gpio = GpioFactory.getInstance();
// provision gpio pin #02 as an input pin with its internal pull down
// resistor enabled
final GpioPinDigitalInput pin0 = gpio.provisionDigitalInputPin(RaspiPin.GPIO_00, PinPullResistance.PULL_UP);
final GpioPinDigitalInput pin1 = gpio.provisionDigitalInputPin(RaspiPin.GPIO_01, PinPullResistance.PULL_UP);
System.out.println("PINs ready");
Thread th = new Thread(new Runnable() {
@Override
public void run() {
while (true) {
if (pin0.isLow()) { // D1 on ground?
s[bits++] = '0';
while (pin0.isLow()) {
}
}
if (pin1.isLow()) { // D1 on ground?
s[bits++] = '1';
while (pin1.isLow()) {
}
}
if (bits == 26) {
bits=0;
Print();
}
}
}
});
th.setPriority(Thread.MAX_PRIORITY);
th.start();
System.out.println("Thread start");
for (;;) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
protected static void Print() {
for (int i = 0; i < 26; i++) {
System.out.write(s[i]);
}
System.out.println();
bits = 0;
}
}
并输出：
10100100111111110110011011
10100100111111110110011011
10100100111111110110011011
10100100111111110110011011
10100100111111110001101110
10010011111111011001101110
10010011111111011001101110
10010011111111011001101110
10010011111111011001101110
10010011111111011001101110
10010011111111011001101110
答案 0 :(得分：1)
您的printf语句可能导致问题。尝试存储数据并在最后打印。 printf往往很慢（它涉及多个上下文切换）。
此外，似乎你没有办法检测你是否错过了一点。我会说尝试超时，所以如果你没有及时获得26位重置你的计数器。这样你就不会四处寻找任何东西，最终导致数据错位。
答案 1 :(得分：0)
我在C和python上用pi和arduino完成了这个。根据我的经验，@ woodrow douglas说你需要捕获一个循环中的位或者使用中断（更好）并使用一个超时，每次收到一个时你会增加，然后一旦你确定你有所有的位就打印出来（超时）。
这是我在arduino上使用中断的方法。
void zero(){
bit_count ++;
bit_holder = (bit_holder << 1) + 0; //shift left one and add a 0
timeout = t;
}
void one(){
bit_count ++;
bit_holder = (bit_holder << 1) + 1; //shift left one and add a 1
timeout = t;
}
void loop() {
timeout --;
if (timeout == 0 && bit_count > 0){
lcd.clear();
lcd.print("Dec:");
lcd.print(bit_holder);
lcd.setCursor(0,1);
lcd.print("Hex:");
lcd.print(String(bit_holder,HEX));
Serial.print("bit count= ");
Serial.println(bit_count);
Serial.print("bits= ");
Serial.println(bit_holder,BIN);
oldbit = bit_holder; //store previous this value as previous
bit_count = 0; //reset bit count
bit_holder = 0; //reset badge number
}
}
我在使用C on Pi时从来没有遇到任何问题，但我确实使用python时遇到了问题，因为它不是实时的。在Python中使用它的唯一方法就是使用中断，我管理得也会把糟糕的读取率降低到200比1，但永远不会完全删除它。
我最后做的是使用一些C来收集这些位，然后使用这些位调用我的python脚本进行处理。
如果您感兴趣，这是我使用的C代码：
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <time.h>
int r1data0 = 6; //pin 22
int r1data1 = 7; // Pin 7
// green goes to same as relay
int r1beep = 0; //pin 11
int r2data0 = 10; /* P1-24 */
int r2data1 = 11; /* P1-26 */
//green goes to same as relay
int r2beep = 0;
int i1 = 0;
int i2 = 0;
//generic variables
int t = 5;
int blank; //blank variable to reset bits
int rel1time = 0;
int rel2time = 0;
int rel1 = 5;
int previoust;
//reader 1variables
int r1bits; // Collected bits storage area
int r1bit_count = 0; //to measure the size of bits
int oldr1bit_count = 0; //somewhere to store bitcount to send to python
int r1timeout; //timout to return correct value
char r1command[40];
int r1ret;
//reader 2 variables
int r2bits; // Collected bits storage area
int r2bit_count = 0; //to measure the size of bits
int oldr2bit_count = 0;
int r2timeout; //timout to return correct value
char r2command[40];
pthread_t threads;
void access_denied(int red){
int pin;
if(red = 1){pin = r1beep;}
if(red = 2){pin = r2beep;}
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW);
delay(300);;
digitalWrite(pin, HIGH);
delay(200);
digitalWrite(pin, LOW);
delay(300);
digitalWrite(pin, HIGH);
delay(200);
digitalWrite(pin, LOW);
delay(300);
digitalWrite(pin, HIGH);
}
void *r1python_thread(void *val){
sprintf(r1command,"python access.py r1 %X %X", oldr1bit_count, val); //build python command
FILE* file = popen(r1command, "r"); //execute command using popen
char buffer[5];
fscanf(file, "%100s", buffer); //read command output
pclose(file);
//printf("buffer is : %s\n", buffer);
rel1time = atoi(buffer); //convert returned string to int
if(rel1time == 0){access_denied(1);}
pthread_exit(NULL);
}
void *r2python_thread(void *val){
sprintf(r2command,"python access.py r2 %X",val); //build python command
FILE* file = popen(r2command, "r"); //execute command using popen
char buffer[5];
fscanf(file, "%100s", buffer); //read command output
pclose(file);
//printf("buffer is : %s\n", buffer);
rel2time = atoi(buffer); //convert returned string to int
pthread_exit(NULL);
}
//reader 1 bit functions
void onebit0(){ //adds a 0
r1bit_count ++; //increase bit count
r1bits = (r1bits << 1) + 0;
r1timeout = t; //reset timeout
}
void onebit1(){ //adds a 1
r1bit_count ++;
r1bits = (r1bits << 1) + 1;
r1timeout = t;
}
//reader 2 bit functions
void twobit0(){ //adds a 0
r2bit_count ++; //increase bit count
r2bits = (r2bits << 1) + 0;
r2timeout = t; //reset timeout
}
void twobit1(){ //adds a 1
r2bit_count ++;
r2bits = (r2bits << 1) + 1;
r2timeout = t;
}
int main(){
wiringPiSetup(); //initialise wiringPi
pinMode (r1data0, INPUT); // set reader 1 data0 as input
pinMode (r1data1, INPUT); // set reader 1 data1 as input
pinMode (r2data0, INPUT); // set reader 2 data0 as input
pinMode (r2data1, INPUT); // set reader 2 data1 as input
//reader 1
wiringPiISR(r1data0, INT_EDGE_FALLING, onebit0); // set interrupt on data 0 if it falls call bit0 function
wiringPiISR(r1data1, INT_EDGE_FALLING, onebit1); // set interrupt on data 1 if it falls call bit1 function
//reader 2
wiringPiISR(r2data0, INT_EDGE_FALLING, twobit0); // set interrupt on data 0 if it falls call bit0 function
wiringPiISR(r2data1, INT_EDGE_FALLING, twobit1); // set interrupt on data 1 if it falls call bit1 function
while (1){ //loop
if (r1bit_count > 0 ){ //if bits is not empty
r1timeout--; // reduce timeout by 1
if(r1timeout == 0){ //and it has timed out ie no more bits coming
//printf("%X\n",r1bits);
pthread_create(&threads, NULL, r1python_thread,(void *) r1bits); //start new thread for python program
oldr1bit_count = r1bit_count;
r1bit_count = 0; //reset bit count
r1bits = blank; //clear bits cariable
r1timeout = t; //reset timeout
}
}
if (r2bit_count > 0 ){ //if bits is not empty
r2timeout--; // reduce timeout by 1
if(r2timeout == 0){ //and it has timed out ie no more bits coming
pthread_create(&threads, NULL, r2python_thread,(void *) r2bits); //start new thread for python program
r2bit_count = 0; //reset bit count
r2bits = blank; //clear bits cariable
r2timeout = t; //reset timeout
}
}
if (rel1time > 0){
pinMode(rel1, OUTPUT);
int diff = time(NULL) - previoust;
if(diff >= 1){
previoust = time(NULL);
rel1time--;
}
}
else{
pinMode(rel1, INPUT);
previoust = time(NULL);
}
delay(1);
}
return 0;
}