我最近开始使用arduino并在 C 中进行编码,偶然发现了一个问题。
一切正常,应该工作:
读取NFC标签>将POST发送到Laravel API>接收对以下内容的正文响应 在液晶显示器上显示
但是该程序非常不一致,这意味着在一段未知的时间(这是一个随机的时间段)之后,该程序会返回连接失败,如显示器返回。
此连接失败后,程序将不会返回到其连接,并且将继续返回连接失败,直到您重新启动程序。
经过数小时的搜索后,我本人无法解决此问题,因此,我要求你们提供帮助。
(不要给我简单的代码作为答案,而是在我正在学习并且想从中学习的同时给我解释。)
硬件:
Arduino MKR1000
Adafruit PN532 NFC / RFID控制器屏蔽(SPI)
监视器返回:
Found chip PN532
Firmware ver. 1.6
Waiting for an ISO14443A card/n
Attempting to connect to SSID: ****
Connected to wifi
SSID: ****
IP Address: ****
signal strength (RSSI):-66 dBm
Starting connection to server...
================= START PROGRAM =======================
Found a card!
UID Length: 4 bytes
UID Value HEX: 67D667E
UID Value Decimal: 6125102126
{"Druppel": "6125102126"}
Connected!
Response:
Tom
Welcome
Succesfull sign in
Found a card!
UID Length: 4 bytes
UID Value HEX: C9DDCA35
UID Value Decimal: 20122120253
{"Druppel": "20122120253"}
Connection failed
代码
#include <SPI.h>
#include <WiFi101.h>
#include <Wire.h>
#include <LiquidCrystal.h>
#include <ArduinoJson.h>
#include <Adafruit_PN532.h>
#define PN532_SCK (9)
#define PN532_MOSI (8)
#define PN532_SS (6)
#define PN532_MISO (10)
#define PN532_IRQ (2)
#define PN532_RESET (7)
#define TIMEOUT 500
Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);
const int rs = 12, en = 11, d4 = 2, d5 = 3, d6 = 4, d7 = 5;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
const int ledPin = 1;
const int errorLedPin = 13;
const int buzzerPin = 0;
int sensorPin = 0;
char SSID_NAME[] = "****";
char SSID_PASS[] = "****";
WiFiClient client;
int status = WL_IDLE_STATUS;
int keyIndex = 0;
char SERVER[] = "****.*****.nl";
char TOKEN[] = "******************";
char API[] = "********";
void printWiFiStatus() {
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
Serial.print("IP Address: ");
Serial.println(WiFi.localIP());
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
lcd.setCursor(0, 0);
lcd.print("SSID: ");
lcd.print(WiFi.SSID());
lcd.setCursor(0, 2);
lcd.print("IP: ");
lcd.print(WiFi.localIP());
}
void setup() {
Serial.begin(9600);
Serial.println("Serial ready");
analogWrite(A3, 0);
lcd.begin(16, 2);
pinMode(ledPin, OUTPUT);
pinMode(errorLedPin, OUTPUT);
pinMode(buzzerPin, OUTPUT);
tone(buzzerPin, 60);
nfc.begin();
uint32_t versiondata = nfc.getFirmwareVersion();
if (! versiondata) {
Serial.print("Didn't find PN53x board");
while (1);
}
Serial.print("Found chip PN5");Serial.println((versiondata>>24) & 0xFF, HEX);
Serial.print("Firmware ver. ");Serial.print((versiondata>>16) & 0xFF, DEC);Serial.print('.'); Serial.println((versiondata>>8) & 0xFF, DEC);
nfc.setPassiveActivationRetries(0xFF);
nfc.SAMConfig();
Serial.print("Waiting for an ISO14443A card"); Serial.println("/n");
if (WiFi.status() == WL_NO_SHIELD) {
Serial.println("WiFi shield not present");
while (true);
}
noTone(buzzerPin);
tone(buzzerPin, 50);
while (status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(SSID_NAME);
status = WiFi.begin(SSID_NAME, SSID_PASS);
delay(100);
}
Serial.println("Connected to wifi");
printWiFiStatus();
Serial.println("\nStarting connection to server...");
Serial.println("\n================= START PROGRAM =======================");
noTone(buzzerPin);
}
void loop() {
digitalWrite(errorLedPin, LOW);
boolean success;
uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };
uint8_t uidLength;
success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, &uid[0], &uidLength);
if (success) {
lcd.clear();
Serial.println("");
Serial.print("Found a card!");
Serial.println("");
Serial.print("UID Length: ");Serial.print(uidLength, DEC);Serial.println(" bytes");
Serial.print("UID Value HEX: ");
String data;
for (uint8_t i=0; i < uidLength; i++)
{
Serial.print(uid[i], HEX);
data = String(data + uid[i]);
}
Serial.println("");
Serial.print("UID Value Decimal: ");
Serial.print(data);
Serial.println("");
lcd.print(data);
delay(100);
digitalWrite(ledPin, HIGH);
tone(buzzerPin, 50);
String PostData = "{\"Druppel\": \"";
PostData = String(PostData + data);
PostData = String(PostData + "\"}");
int PostDataLength = PostData.length() + 1;
delay(100);
noTone(buzzerPin);
char char_array[PostDataLength];
PostData.toCharArray(char_array, PostDataLength);
Serial.println(PostData);
delay(500);
if(!client.connect(SERVER, 80)) {
Serial.println(F("Connection failed"));
digitalWrite(errorLedPin, HIGH);
return;
}
Serial.println(F("Connected!"));
client.println("POST /api/******?api_token=****************** HTTP/1.1");
client.println("Host: ****.*****.nl");
client.println("Cache-Control: no-cache");
client.println("Content-Type: application/json");
client.print("Content-Length: ");
client.println(PostDataLength);
client.println();
client.println(PostData);
client.println(F("Connection: close"));
if (client.println() == 0) {
Serial.println(F("Failed to send request"));
return;
}
char status[32] = {0};
client.readBytesUntil('\r', status, sizeof(status));
if (strcmp(status, "HTTP/1.1 200 OK") != 0) {
Serial.print(F("Unexpected response: "));
Serial.println(status);
return;
}
char endOfHeaders[] = "\r\n\r\n";
if (!client.find(endOfHeaders)) {
Serial.println(F("Invalid response"));
return;
}
const size_t capacity = JSON_OBJECT_SIZE(3) + JSON_ARRAY_SIZE(2) + 60;
DynamicJsonBuffer jsonBuffer(capacity);
JsonObject& root = jsonBuffer.parseObject(client);
if (!root.success()) {
Serial.println(F("Parsing failed!"));
return;
}
Serial.println(F("Response:"));
Serial.println(root["User"].as<char*>());
Serial.println(root["Status"].as<char*>());
lcd.setCursor(0, 2);
lcd.print(root["User"].as<char*>());
lcd.setCursor(0, 0);
lcd.print(root["Status"].as<char*>());
client.stop();
digitalWrite(ledPin, LOW);
digitalWrite(errorLedPin, HIGH);
Serial.println("");
Serial.println("Succesfull sign in");
delay(3000);
lcd.clear();
} else
{
Serial.println("Timed out waiting for a card");
}
}
答案 0 :(得分:2)
不要使用String类。它会使内存堆碎片化,从而导致崩溃。使用C字符串(零终止的char数组)。如果您不熟悉strcat
和sprintf
函数,则可以使用我的StreamLib库中的CStringBuilder。该库可在Arduino IDE的库管理器中找到。
char PostData[200];
CStringBuilder sb(PostData, sizeof(PostData));
sb.print("{\"Druppel\": \"");
for (uint8_t i=0; i < uidLength; i++)
{
sb.print(uid[i]);
//sb.printf("%02x", uid[i]); // for hex aligned with 0
}
sb.print("\"}");
Serial.println(sb.length());
Serial.println(PostData);