Good way to recognise fake NRF24L01+ is measurement of current consumption. The best is measure current in power down mode, genuine chips have about 500nA (datasheet says 900nA) but fake copies has over 3uA usually 4uA.

In transmit or receive mode have fakes a little higher consumption than genuine. Genuine Tx-0dBm~11mA, Rx~13mA. Fakes have about 2mA more than genuine and it's consuption is out of datasheet range!

step-up regulator is not needed for 3V the easiest way is removing stabilizer an diode and replace by wire. HC-SR01 sensor inner works with 3 to 5V

The main difference of this module is: this module uses genuine NRF24L01 IC, another brown PCBs contain in most cases fake NRF24L01, probably overlabeled SI24R1!

I think that range was better than fake NRF.

Good way to recognise fake modules is measurement current in power down mode. Genuine have about 500nA but fake about 4uA! But if you use PA+LNA version the power consumption is a little higher.

I use red PCB marked as E01-ML01D and there is range better than modules with fake NRF.

You can compare power consuption, if you received this new module. I think that your old module contain fake NRF and have worse current consumption. Original module have about 1uA in sleep mode, fake module have worse!

At this module seller declared power down mode current under 1uA, you can check your current module in power down mode, if current is significantly different you have got fake.

Blue - parts to be removed
Red - wire or tin short circuit

I changed to development version of Nodemanager this remove compilation errors and then found that recomended library from Sparkfun not work. Then i edited header file SensorSI7021.h to work with Adafruit library and it works
my SensorSI7021.h:

/*
* The MySensors Arduino library handles the wireless radio link and protocol
* between your home built sensors/actuators and HA controller of choice.
* The sensors forms a self healing radio network with optional repeaters. Each
* repeater and gateway builds a routing tables in EEPROM which keeps track of the
* network topology allowing messages to be routed to nodes.
*
* Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
* Copyright (C) 2013-2017 Sensnology AB
* Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
* 2021 modified by Libor Kozak to work with Adafruit library: https://github.com/adafruit/Adafruit_Si7021
*
* Documentation: http://www.mysensors.org
* Support Forum: http://forum.mysensors.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*/
#ifndef SensorSI7021_h
#define SensorSI7021_h

/*
SensorSI7021: temperature and humidity sensor
*/

#include <Wire.h>
//#include <SI7021.h>
#include <Adafruit_Si7021.h>

class SensorSI7021: public Sensor {
protected:
	Adafruit_Si7021* _si7021;//SI7021* _si7021;
	
public:
	SensorSI7021(uint8_t child_id = 0): Sensor(-1) {
		_name = "SI7021";
		children.allocateBlocks(2);
		new Child(this,FLOAT,nodeManager.getAvailableChildId(child_id),S_TEMP,V_TEMP,_name);
		new Child(this,FLOAT,child_id > 0 ? nodeManager.getAvailableChildId(child_id+1) : nodeManager.getAvailableChildId(child_id),S_HUM,V_HUM,_name);
	};
	
	// define what to do during setup
	void onSetup() {
		_si7021 = new Adafruit_Si7021();
		_si7021->begin();
	};

	// define what to do during loop
	void onLoop(Child* child) {
		// temperature sensor
		if (child->getType() == V_TEMP) {
			// read the temperature
			float temperature = _si7021->readTemperature();
			// convert it
			//temperature = nodeManager.celsiusToFahrenheit(temperature);
			// store the value
			child->setValue(temperature);
		}
		// Humidity Sensor
		else if (child->getType() == V_HUM) {
			// read humidity
			float humidity = _si7021->readHumidity();
			// store the value
			child->setValue(humidity);
		}
	};
};
#endif

Hi all, today i tested my SI7021 sensors and Nodemanager, but they not working very well.

After power on sensor, i receive presentation of two channels (temp and humidity), but then i receive only V_TEMP updates and never recived V_HUM, have anyone working sketch with nodemanager or can check my code, i start from template from nodemanager examples, i also checked sensor with my MCP2221 I2C<>USB converter and here it works.

/*
* The MySensors Arduino library handles the wireless radio link and protocol
* between your home built sensors/actuators and HA controller of choice.
* The sensors forms a self healing radio network with optional repeaters. Each
* repeater and gateway builds a routing tables in EEPROM which keeps track of the
* network topology allowing messages to be routed to nodes.
*
* Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
* Copyright (C) 2013-2017 Sensnology AB
* Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
*
* Documentation: http://www.mysensors.org
* Support Forum: http://forum.mysensors.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*/

/**************************
Template

This sketch can be used as a template since containing the most relevant MySensors library configuration settings, 
NodeManager's settings, all its the supported sensors commented out and a sketch structure fully functional to operate with
NodeManager. Just uncomment the settings you need and the sensors you want to add and configure the sensors in before()
*/

/**********************************
 * MySensors node configuration
 */

// General settings
#define SKETCH_NAME "SI7021"
#define SKETCH_VERSION "1.0"
//#define MY_DEBUG
#define MY_NODE_ID 100

// NRF24 radio settings
#define MY_RADIO_RF24
//#define MY_RF24_ENABLE_ENCRYPTION
//#define MY_RF24_CHANNEL 125
//#define MY_RF24_PA_LEVEL RF24_PA_HIGH
//#define MY_DEBUG_VERBOSE_RF24
//#define MY_RF24_DATARATE RF24_250KBPS

// RFM69 radio settings
//#define MY_RADIO_RFM69
//#define MY_RFM69_FREQUENCY RFM69_433MHZ
//#define MY_IS_RFM69HW
//#define MY_RFM69_NEW_DRIVER
//#define MY_RFM69_ENABLE_ENCRYPTION
//#define MY_RFM69_NETWORKID 100
//#define MY_DEBUG_VERBOSE_RFM69
//#define MY_RF69_IRQ_PIN D1
//#define MY_RF69_IRQ_NUM MY_RF69_IRQ_PIN
//#define MY_RF69_SPI_CS D2
//#define MY_RFM69_ATC_MODE_DISABLED

// RFM95 radio settings
//#define MY_RADIO_RFM95
//#define MY_RFM95_FREQUENCY (RFM95_868MHZ)
//#define MY_DEBUG_VERBOSE_RFM95
//#define MY_RFM95_MAX_POWER_LEVEL_DBM (20)
//#define MY_RFM95_IRQ_PIN D1
//#define MY_RFM95_IRQ_NUM MY_RFM95_IRQ_PIN
//#define MY_RFM95_CS_PIN D8

// RS485 serial transport settings
//#define MY_RS485
//#define MY_RS485_BAUD_RATE 9600
//#define MY_RS485_DE_PIN 2
//#define MY_RS485_MAX_MESSAGE_LENGTH 40
//#define MY_RS485_HWSERIAL Serial1

// Message signing settings
//#define MY_SIGNING_SOFT
//#define MY_SIGNING_SOFT_RANDOMSEED_PIN 7
//#define MY_SIGNING_REQUEST_SIGNATURES
//#define MY_SIGNING_ATSHA204
//#define MY_SIGNING_ATSHA204_PIN 4
//#define MY_SIGNING_REQUEST_SIGNATURES

// OTA Firmware update settings
//#define MY_OTA_FIRMWARE_FEATURE
//#define OTA_WAIT_PERIOD 300
//#define FIRMWARE_MAX_REQUESTS 2
//#define MY_OTA_RETRY 2

// OTA debug output
//#define MY_DEBUG_OTA (0)
//#define MY_OTA_LOG_SENDER_FEATURE
//#define MY_OTA_LOG_RECEIVER_FEATURE
//#define MY_DEBUG_OTA_DISABLE_ACK

// Advanced settings
//#define MY_BAUD_RATE 9600
//#define MY_SMART_SLEEP_WAIT_DURATION_MS 500
#define MY_SPLASH_SCREEN_DISABLED
//#define MY_DISABLE_RAM_ROUTING_TABLE_FEATURE
//#define MY_SIGNAL_REPORT_ENABLED

// Optimizations when running on 2032 Coin Cell. Also set nodeManager.setSleepBetweenSend(500) and run the board at 1Mhz
#define MY_TRANSPORT_UPLINK_CHECK_DISABLED
//#define MY_TRANSPORT_WAIT_READY_MS  5000
//#define MY_SLEEP_TRANSPORT_RECONNECT_TIMEOUT_MS 2000
//#define MY_PARENT_NODE_ID 0
//#define MY_PARENT_NODE_IS_STATIC

/**********************************
 * MySensors gateway configuration
 */
 
// Common gateway settings
//#define MY_REPEATER_FEATURE

// Serial gateway settings
//#define MY_GATEWAY_SERIAL

// Ethernet gateway settings
//#define MY_GATEWAY_W5100

// ESP8266 gateway settings
//#define MY_GATEWAY_ESP8266
//#define MY_ESP8266_SSID ""
//#define MY_ESP8266_PASSWORD ""

// Gateway networking settings
//#define MY_IP_ADDRESS 192,168,178,87
//#define MY_IP_GATEWAY_ADDRESS 192,168,178,1
//#define MY_IP_SUBNET_ADDRESS 255,255,255,0
//#define MY_PORT 5003
//#define MY_GATEWAY_MAX_CLIENTS 2
//#define MY_USE_UDP

// Gateway MQTT settings
//#define MY_GATEWAY_MQTT_CLIENT
//#define MY_CONTROLLER_IP_ADDRESS 192, 168, 178, 68
//#define MY_PORT 1883
//#define MY_MQTT_USER "username"
//#define MY_MQTT_PASSWORD "password"
//#define MY_MQTT_CLIENT_ID "mysensors-1"
//#define MY_MQTT_PUBLISH_TOPIC_PREFIX "mygateway1-out"
//#define MY_MQTT_SUBSCRIBE_TOPIC_PREFIX "mygateway1-in"

// Gateway inclusion mode
//#define MY_INCLUSION_MODE_FEATURE
//#define MY_INCLUSION_BUTTON_FEATURE
//#define MY_INCLUSION_MODE_DURATION 60
//#define MY_DEFAULT_LED_BLINK_PERIOD 300

// Gateway Leds settings
//#define MY_DEFAULT_ERR_LED_PIN 4
//#define MY_DEFAULT_RX_LED_PIN  5
//#define MY_DEFAULT_TX_LED_PIN  6

/***********************************
 * NodeManager configuration
 */

#define NODEMANAGER_DEBUG OFF
#define NODEMANAGER_INTERRUPTS OFF
#define NODEMANAGER_SLEEP ON
#define NODEMANAGER_RECEIVE OFF
#define NODEMANAGER_DEBUG_VERBOSE OFF
#define NODEMANAGER_POWER_MANAGER OFF
#define NODEMANAGER_CONDITIONAL_REPORT OFF
#define NODEMANAGER_EEPROM OFF
#define NODEMANAGER_TIME OFF
#define NODEMANAGER_RTC OFF
#define NODEMANAGER_SD OFF
#define NODEMANAGER_HOOKING OFF
#define NODEMANAGER_OTA_CONFIGURATION OFF
#define NODEMANAGER_SERIAL_INPUT OFF

// import NodeManager library (a nodeManager object will be then made available)
#include <MySensors_NodeManager.h>

/***********************************
 * Add your sensors
 */

#include <sensors/SensorSI7021.h>
SensorSI7021 si7021;

/***********************************
 * Main Sketch
 */

// before
void before() {
	
  /***********************************
   * Configure your sensors
   */
  // EXAMPLES:
  // report measures of every attached sensors every 10 seconds
  nodeManager.setReportIntervalSeconds(10);
  // report measures of every attached sensors every 10 minutes
  //nodeManager.setReportIntervalMinutes(10);
  // set the node to sleep in 30 seconds cycles
  //nodeManager.setSleepSeconds(30);
  // set the node to sleep in 5 minutes cycles
  //nodeManager.setSleepMinutes(5);
  // report battery level every 10 minutes
  //battery.setReportIntervalMinutes(60);
  // set an offset to -1 to a thermistor sensor
  //thermistor.setOffset(-1);
  // change the id of a the first child of a sht21 sensor
  //sht21.children.get(1)->setChildId(5);
  // report only when the analog value is above 40%
  //analog.children.get(1)->setMinThreshold(40);
  // power all the nodes through dedicated pins
  //nodeManager.setPowerManager(power);

  // call NodeManager before routine
  nodeManager.before();
}

// presentation
void presentation() {
  // call NodeManager presentation routine
  nodeManager.presentation();
}

// setup
void setup() {
  // call NodeManager setup routine
  nodeManager.setup();
}

// loop
void loop() {
  // call NodeManager loop routine
  nodeManager.loop();
}

#if NODEMANAGER_RECEIVE == ON
// receive
void receive(const MyMessage &message) {
  // call NodeManager receive routine
  nodeManager.receive(message);
}
#endif

#if NODEMANAGER_TIME == ON
// receiveTime
void receiveTime(unsigned long ts) {
  // call NodeManager receiveTime routine
  nodeManager.receiveTime(ts);
}
#endif

at compilig i got two warnings:

In file included from C:\Users\Libor\Documents\Arduino\libraries\NodeManager-master/MySensors_NodeManager.h:87:0,
                 from C:\Users\Libor\Documents\Arduino\projects\NodeManager_test\NodeManager_test.ino:176:
C:\Users\Libor\Documents\Arduino\libraries\NodeManager-master/nodemanager/Sensor.cpp: In member function 'void Sensor::presentation()':
C:\Users\Libor\Documents\Arduino\libraries\NodeManager-master/nodemanager/Sensor.cpp:135:54: warning: invalid conversion from 'uint8_t {aka unsigned char}' to 'mysensors_sensor_t' [-fpermissive]
   present(child->getChildId(), child->getPresentation(), child->getDescription(), nodeManager.getAck());
                                ~~~~~~~~~~~~~~~~~~~~~~^~
In file included from C:\Users\Libor\Documents\Arduino\libraries\MySensors/MySensors.h:433:0,
                 from C:\Users\Libor\Documents\Arduino\libraries\NodeManager-master/MySensors_NodeManager.h:43,
                 from C:\Users\Libor\Documents\Arduino\projects\NodeManager_test\NodeManager_test.ino:176:
C:\Users\Libor\Documents\Arduino\libraries\MySensors/core/MySensorsCore.cpp:375:6: note:   initializing argument 2 of 'bool present(uint8_t, mysensors_sensor_t, const char*, bool)'
 bool present(const uint8_t childSensorId, const mysensors_sensor_t sensorType,
      ^~~~~~~

Hi, i have problem with my domoticz and mysensors temp and humidity sensors, sometimes is recognized as one device with temp and humidity, sometimes as temp only and humidity only device with different ID, can anyone help me?

I use RPi 3B with domoticz and local network gateway with SPI NRF24L01+

ATMEGA328PU-KR which i see on image is fake clone and really not product of Atmel (now bought by Microchip)

Hi all, i try NRF51822-04 module with this sketch and Si7021 as GY-21 sensor, communication over radio works great, but i still got Humidity 118% and Temperature 128°C

can anyone help me?

Si7021 is connected to P0.10 - SCL and P0.4 - SDA

@VaZso
Today i tested this method, and ... It works :-D:-D:-D:-D
Fake over 1mA, genuine about 0,5uA
Thank you.

But this can't be probably used as proof in disputes on aliexpress. But for quick test is this method insuperable.

Good way to recognise fake NRF24L01+ is measurement of current consumption. The best is measure current in power down mode, genuine chips have about 500nA (datasheet says 900nA) but fake copies has over 3uA usually 4uA.

In transmit or receive mode have fakes a little higher consumption than genuine. Genuine Tx-0dBm~11mA, Rx~13mA. Fakes have about 2mA more than genuine and it's consuption is out of datasheet range!

@Igor-Antolić I have 11pcs of this: http://www.ebay.com/itm/401239381506?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I think that all other parts with NRF24L01+ marked as E01-ML01xx are genuine, but from china is hard to vouch for anything. Is until another chinese factory do make this type of red boards with counterfeit IC.

But is only one chance to make this better, testing received goods for declared parameters and if you received counterfeits then don't pay for it and opening disputes and leaving negative feedback for this sellers and don't leave sellers get profit on this fake goods!

The main difference of this module is: this module uses genuine NRF24L01 IC, another brown PCBs contain in most cases fake NRF24L01, probably overlabeled SI24R1!

I think that range was better than fake NRF.

Good way to recognise fake modules is measurement current in power down mode. Genuine have about 500nA but fake about 4uA! But if you use PA+LNA version the power consumption is a little higher.

I use red PCB marked as E01-ML01D and there is range better than modules with fake NRF.

You can compare power consuption, if you received this new module. I think that your old module contain fake NRF and have worse current consumption. Original module have about 1uA in sleep mode, fake module have worse!

At this module seller declared power down mode current under 1uA, you can check your current module in power down mode, if current is significantly different you have got fake.

@Mercury69 PIR is based on interrupts, which wake-up processor from sleep mode, Arduinos based on ATMEGA328 have only two these pins, pin 2 and 3.

You can use 2 PIRs with detection which was fired, if you need more than two PIRs you can connect each PIR to any digital input of arduino and common signal OR-ing from all PIRs to generate interrupt to pin 2 or 3. Then if you wake-up by interrupt you can software test all of digital inputs and resolve which PIR was fired.