问题

    EFR32无线壁虎芯片在2.4GHz的最优负载阻抗是多少？

回答

    最优负载阻抗是由2.4GHz频段的Load-Pull测量来确定的。最优负载阻抗产生最好的Tx功率效率，而且Rx的性能也接近它最优值。

    EFR32有一个单端2.4GHz射频管脚为接收和发射公用（2G4RF_IOP）。另外一个管脚2G4RF_ION必须连接到地，并且不能与2G4RF_IOP管脚互换。

    2G4RF_IOP不需要上拉到VDD电源，因2.4GHz PA是从一个另外的PAVDD电源管脚供电，再者RF管脚对地是直流短路的。 

    单端2G4RF_IOP 管脚在整个2.4GHz ISM频段上对于高于+10dBm输出功率时最优阻抗是23+j11.5 ohms，对于较低输出功率时的最优阻抗是20+j10.6 ohms。

    详细内容见AN930应用报告。

    英文原文： https://www.silabs.com/community/wireless/zigbee-and-thread/knowledge-base.entry.html/2016/11/08/efr32_optimum_loadi-RDC1

Question: What can I do to get around the post build batch file invocation failures with Ember ZNet 5.7.2  on Simplicity Studio 4?

Answer: 

The post build batch file takes the *.out file from the build and generates 32 bit *.s37 file and *.ebl file. 

There are 2 problems that occur with the post build batch file invocation:

1. The path of the batch file is incorrect after generation and therefore the post build process does not get executed. To fix this, edit SiliconLabs\SimplicityStudio\v4\developer\stacks\znet\v5.7.2.0\tool\appbuilder\addition.slsproj and add single quotes around the .bat path like so - 

  $-studioCmdLaunchCommand$ '$genDir$/app/builder/$deviceName$/$deviceName-$.bat' ${BuildArtifactFileBaseName} ..

Since this is a change in the SDK, you will need to close and reopen Studio and refresh the SDK (Window -> Preferences -> Simplicity Studio -> SDK's -> Select only the SDK 5.7.2  – If not, this operation will take a long time as all installed SDK's will be refreshed > Press ctrl + shift + F5 to refresh. 

2. The path to the em3xx_convert.exe file is not reachable. To fix this, add windows environment variable to define ISA3_UTILS DIR to wherever your em3xx_convert.exe file is. Example : _

Silicon Labs recently released an update that included ZNet 6.4.1. The update was to correct an issue in RAIL, modifying the Gecko SDK to 2.4.1, RAIL_LIB 2.5.1.0 and Bluetooth SDK 2.10.1.

The update contains no bug fixes for Zigbee, and updating has no effect on your ZNet stack or applications. Both 6.4.0 and 6.4.1 will be Zigbee certified.

If you are doing any Dynamic Multiprotocol (DMP) with BLE, we do recommend installing the updates. Please see the Bluetooth release notes if this may apply to you.

1.Background:

As you know, the architecture of the gateway is as follows:

The MQTT broker could be deployed either inside or outside the gateway.  As security is becoming more and more important in Iot network, it could be a critical problem if the broker is outside the gateway. It’s recommended to connect the gateway and the MQTT broker over a secure connection. This article demonstrates how to connect the gateway to a MQTT broker over TLS.

2.Steps of setting up the secured connection:

The gateway used in this demonstration is based on Z3GatewayHost(EmberZnet 6.4.0), running on Cygwin + Win10. The broker is “Apache Apollo” running on a Ubuntu 18.04 system.

2.1 Setting up the broker:

       2.1.1 Install broker

Download “Apache Apollo” from https://activemq.apache.org/apollo/download.html. Uncompress the package.

       2.1.2 Create a broker instance

jim@jimubuntu:~/develop/broker/apache-apollo-1.7.1$ bin/apollo create mybroker

       2.1.3 Run the broker instance

jim@jimubuntu:~/develop/broker/apache-apollo-1.7.1$ cd mybroker/bin
jim@jimubuntu:~/develop/broker/apache-apollo-1.7.1/mybroker/bin$ ./apollo-broker run

    _____                .__  .__
   /  _  \ ______   ____ |  | |  |   ____
  /  /_\  \\____ \ /  _ \|  | |  |  /  _ \
 /    |    \  |_> >  <_> )  |_|  |_(  <_> )
 \____|__  /   __/ \____/|____/____/\____/
         \/|__|  Apache Apollo (1.7.1)


Loading configuration file '/home/jim/develop/broker/apache-apollo-1.7.1/mybroker/etc/apollo.xml'.
INFO  | OS     : Linux 4.15.0-36-generic (Ubuntu 18.04.1 LTS)
INFO  | JVM    : OpenJDK 64-Bit Server VM 1.8.0_181 (Oracle Corporation)
INFO  | Apollo : 1.7.1 (at: /home/jim/develop/broker/apache-apollo-1.7.1)
INFO  | OS is restricting the open file limit to: 100000
INFO  | Accepting connections at: tcp://0.0.0.0:61613
INFO  | Accepting connections at: tls://0.0.0.0:61614
INFO  | Starting store: leveldb store at /home/jim/develop/broker/apache-apollo-1.7.1/mybroker/data
INFO  | Accepting connections at: ws://0.0.0.0:61623/
INFO  | Accepting connections at: wss://0.0.0.0:61624/
INFO  | virtual host startup is waiting on store startup
INFO  | virtual host startup is no longer waiting.  It waited a total of 1 seconds.
INFO  | Administration interface available at: https://127.0.0.1:61681/
INFO  | Administration interface available at: http://127.0.0.1:61680/

        2.1.4 Get the IP address of the broker

jim@jimubuntu:~$ ifconfig
enp0s8: flags=4163  mtu 1500
        inet 192.168.56.101  netmask 255.255.255.0  broadcast 192.168.56.255
        inet6 fe80::7b92:ce7b:8c37:d508  prefixlen 64  scopeid 0x20
        ether 08:00:27:2c:b8:a6  txqueuelen 1000  (Ethernet)
        RX packets 130  bytes 16701 (16.7 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 185  bytes 34178 (34.1 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

2.2 Setting up the gateway:

       2.2.1 create the Z3GatewayHost project, then select the following plugins

• Paho MQTT
• Device Table
• OTA Bootload Cluster Server
• Command Relay
• cJSON
• Gateway Relay Mqtt
• Gateway MQTT Transport

In the properties page of the plugin “Gateway MQTT Transport”, set the URL of the broker to ssl://192.168.56.101:61614. The prefix of the URL should be either “tcp://” for non-secured connection or “ssl://” for secured connection.

       2.2.2 Define a macro “OPENSSL” to enable openssl

       2.2.3 Save and generate the project

       2.2.4 Modify the Makefile of the project

First, add one source file into the makefile:

../../../util/third_party/paho.mqtt.c/src/SSLSocket.c

Second, link the ssl and crypto library to the project:

LINKER_FLAGS ?=-lssl -lcrypto

       2.2.5 Add initialization of the ssl option in the function emberAfPluginTransportMqttInitCallback

MQTTAsync_SSLOptions g_ssl_options = { {'M', 'Q', 'T', 'S'}, 0, NULL, NULL, NULL, NULL, NULL, 0 };  //defined the ssl option. 

void emberAfPluginTransportMqttInitCallback(void)
{
  emberAfCorePrintln("MQTT Client Init");
  EmberEUI64 eui64;
  char euiString[EUI64_NULL_TERMINATED_STRING_SIZE] = { 0 };
  int status;

  status = pthread_mutex_init(&mqttConnectedLock, NULL);
#ifndef EMBER_TEST
  if (status != 0) {
    emberAfCorePrintln("pthread_mutex_init failed, status = 0x%X", status);
    assert(false);
  }
#endif

  // Save our EUI information
  emberAfGetEui64(eui64);
  snprintf(euiString,
           EUI64_NULL_TERMINATED_STRING_SIZE,
           "%02X%02X%02X%02X%02X%02X%02X%02X",
           eui64[7],
           eui64[6],
           eui64[5],
           eui64[4],
           eui64[3],
           eui64[2],
           eui64[1],
           eui64[0]);

  strcat(mqttClientIdString, EMBER_AF_PLUGIN_TRANSPORT_MQTT_CLIENT_ID_PREFIX);
  strcat(mqttClientIdString, euiString);
  emberAfCorePrintln("MQTT Client ID = %s", mqttClientIdString);

  status = MQTTAsync_create(&mqttClient,
                            EMBER_AF_PLUGIN_TRANSPORT_MQTT_BROKER_ADDRESS,
                            mqttClientIdString,
                            MQTTCLIENT_PERSISTENCE_NONE,
                            NULL); // persistence_context is NULL since
                                   // persistence is NONE
  if (status != MQTTASYNC_SUCCESS) {
    emberAfCorePrintln("MQTTAsync_create failed, status = 0x%X", status);
    assert(false);
  }

  status = MQTTAsync_setCallbacks(mqttClient,
                                  NULL, // context is NULL, no app context used
                                        // here
                                  mqttConnectionLostCallback,
                                  mqttMessageArrivedCallback,
                                  NULL); // dc is NULL,
                                         // MQTTAsync_deliveryComplete unusued
  if (status != MQTTASYNC_SUCCESS) {
    emberAfCorePrintln("MQTTAsync_setCallbacks failed, status = 0x%X", status);
    assert(false);
  }

  //init the ssl option used in the connecting process
  mqttConnectOptions.username = "admin";
  mqttConnectOptions.password = "password";
  mqttConnectOptions.ssl = &g_ssl_options;

  mqttConnectOptions.keepAliveInterval = MQTT_KEEP_ALIVE_INTERVAL_S;
  mqttConnectOptions.cleansession = 1;
  mqttConnectOptions.onSuccess = mqttConnectSuccessCallback;
  mqttConnectOptions.onFailure = mqttConnectFailureCallback;
  mqttConnectOptions.context = mqttClient;

// Note that this won't try to connect to MQTT if we are in EMBER_TEST mode
// because the simulator doesn't work with this plugin, we will simply not
// start and never fire our connection event
#ifndef EMBER_TEST
  // Start our connection event timer to attempt to connect to the broker
  emberEventControlSetActive(
    emberAfPluginTransportMqttBrokerReconnectEventControl);
#endif
}

       2.2.6 Build the project and run

The gateway will keep trying to connect the MQTT broker after startup.

3.Demostration:

       3.1 On the gateway side:

       3.2 On the broker side:

       3.3 The communication between the gateway of the broker is over TLS:

       3.4 Test with MQTT client:

       3.4.1 Install MQTT client

Download paho.ui.app from https://repo.eclipse.org/content/repositories/paho-releases/org/eclipse/paho/org.eclipse.paho.ui.app/, uncompress the package.

       3.4.2 Connect the MQTT to broker

Click “+” button to create a new connection, and then set the URL of the broker, then fill the account info or ssl info in the “options” panel, and then connect.

After connected, you can send commands to gateway through the topic “gw//commands”. (Please refer to section 6.3 of UG129 to get detail the topics supported by Z3GatewayHost).

       3.4.3 Send commands to gateway

The message must be in JSON format (Please refer to section 6.3 of UG129 for details). Here we send below commands to the topic “gw/000B57FFFE648DD8/commands”:

{
"commands":[
{
"commandcli":"zcl on-off toggle",
"postDelayMs":0
},
{
"commandcli":"send 0xf4ef 1 1",
"postDelayMs":0
}
]
}

If the commands are received by the gateway, it will send a on-off toggle message to the node 0xf4ef. We can capture the Zigbee packets in the sniffer.

Someone may encounter the ezspForceReset error during launching the host application. the most common cause of this issue is uart or spi communication failure.here are some suggestions for debugging this issue.

1. To make sure uart/spi work properly on the host part.

• make sure the driver of uart/spi works properly
• choose the proper uart/spi port(driver file) for host application when lanuching the host application

2. To make sure the ncp firmware works properly.

here is a simple way to indentify whether the ncp firmware works properly.

• Connect to the WSTK or ISA3 and start capture on Simplicity Studio.

• reset the ncp and you will find the stack version of the ncp is printed on Events window.

If there is no log printed when you reset the ncp. that means the ncp doesn't work properly.In this case, it is recommended to use pre-build ncp image to exclude the firmware issue. if the pre-build ncp image for your part number can't be found in ncp-images folder. You can only build the customized ncp image by reference to https://www.silabs.com/documents/public/application-notes/an1010-customized-ncp.pdf

3. If the host application still can't be launched successfully, you have to capture the waveform from the uart or spi pins with logic analyzer or oscilloscope, and then compare the waveform with the expected one which described in https://www.silabs.com/documents/public/application-notes/an711-ezsp-spi-host-interfacing-guide.pdf or https://www.silabs.com/documents/public/application-notes/an706-ezsp-uart-host-interfacing-guide.pdf

As you may know, we can use the EZSP frame setPreinstalledCbkeData(0xA2) and setPreinstalledCbkeData283k1(0xED) to set the device's CA public key and 283k1 curve CA public key, which has been mentioned in UG100(page107). The associated APIs are ezspSetPreinstalledCbkeData() and ezspSavePreinstalledCbkeData283k1().

Please note, there is a difference between these two APIs.

Regarding the ezspSetPreinstalledCbkeData(), you can call it directly after inputing the three parameters (caPublic, myCert, myKey). But regarding the ezspSavePreinstalledCbkeData283k1(), it can't. You need set EZSP_VALUE_CERTIFICATE_283K1/ EZSP_VALUE_PUBLIC_KEY_283K1/ EZSP_VALUE_PRIVATE_KEY_283K1 firstly before you call the ezspSavePreinstalledCbkeData283k1(). Actually, we have an new API(emberSetPreinstalledCbkeData283k1) to implement the funciton. Please refer to below code.

// sample code in ezsp.c
EmberStatus emberSetPreinstalledCbkeData283k1(EmberPublicKey283k1Data *caPublic,
                                              EmberCertificate283k1Data *myCert,
                                              EmberPrivateKey283k1Data *myKey)
{
  ezspSetValue(EZSP_VALUE_CERTIFICATE_283K1, EMBER_CERTIFICATE_283K1_SIZE, emberCertificate283k1Contents(myCert));
  ezspSetValue(EZSP_VALUE_PUBLIC_KEY_283K1, EMBER_PUBLIC_KEY_283K1_SIZE, emberPublicKey283k1Contents(caPublic));
  ezspSetValue(EZSP_VALUE_PRIVATE_KEY_283K1, EMBER_PRIVATE_KEY_283K1_SIZE, emberPrivateKey283k1Contents(myKey));
  return ezspSavePreinstalledCbkeData283k1();
}

The CBKE Data associated with ECC 283k1 is sent in three separate EZSP commands because the total length of the combined data is greater than the max EZSP message length (133).  The first EZSP command will contain the certificate followed next by the public key and finally the private key. Once all the data has been received by the NCP a 4th command is sent by the host indicating to push the data into permanent storage.

In 802.15.4 specification, it mentions the PHY shall provide the capability to perform CCA. Zigbee stack is based on 802.15.4, what is the CCA threshold for Zigbee device? The default CCA threshold of GB868 SubGHz is -87dBm, and the default CCA threshold of 2.4GHz is -75dBm.

As you may know there is a MFG token (TOKEN_MFG_CCA_THRESHOLD) can be set to override the default CCA threshold(s) by setting this token if your design uses a Low-Noise Amplifier (LNA). An LNA changes the gain on the radio input which results in the radio “seeing” a different energy level than if no LNA was used. If you use an LNA in your design, you will need add the gain of LNA to the default CCA threshold, then write to this MFG token. Please refer to the AN961 for more information.

You may have question where the two default values come from? Actually, these two values are defined by specification, 802.15.4-2006 mentioned the ED threshold shall correspond to a received signal power of at most 10 dB above the specified receiver sensitivity. Sensitivity requirement for 2.4 GHz is -85dBm, hence CCA threshold = -75dBm, GB868 sensitivity is -97dBm per Zigbee R22 spec, hence CCA threshold =-87dBm.

问题

    如何将TCXO连接到EFR32？

回答

    EFR32主时钟可以用TCXO作为时钟源。为了用TCXO时钟源来运行，需要重新配置时钟管理单元中的HFXO寄存器。如下的配置可参阅EFR32参考手册获取更多细节：
    •CMU_HFXOCTRL - HFXO 控制寄存器。
    •HFXO Mode该位置1使单端TCXO替代晶体振荡器。
    •该位默认置0，表示选择晶体振荡器。

    •CMU_OSCENCMD - 晶振使能命令寄存器。
    •HFXOEN 该位置1使HFXO Mode寄存器生效。
    •该位默认置0，不使能HFXO。

    •HFXODIS 如果不用或者用不到TCXO或晶体振荡器，将该位置1使复位振荡器到默认设置。
    •该位缺省置0。

    •CMU_HFXOSTARTUPCTRL - HFXO 启动控制/ CMU_HFXOSTEADYSTATECTRL - HFXO 稳态控制。
    •CTUNE 为补偿额外负载电容，相对于晶振来说用TCXO时的CTUNE可能需要设置成低值或0。

    以上寄存器设置要确保物理上将TCXO连接到芯片的HFXTAL_N管脚。芯片的HFXTAL_P管脚不用连接。

    英文原文： https://www.silabs.com/community/wireless/zigbee-and-thread/knowledge-base.entry.html/2016/11/07/using_a_tcxo_withan-Uue4

Background:

Sometimes customers want to actively send custom messages from NCP to host. For example, customer connects GPIO of the NCP to an alarm sensor. When the alarm occurs, the level of the GPIO changes and an event should be reported to the host actively. The attached example in this article demonstrates how to send a custom message actively from NCP to host. Customer needs to enable XNCP library and then use the API “emberAfPluginXncpSendCustomEzspMessage” to send custom message from NCP to host.

Example:

Implement an example project base on the default ncp-uart-hw example and Z3GatewayHost example within EmberZnet 6.4.0.

The NCP example is running on WSTK+BRD4162, and the host is running on Cygwin. NCP connects to the host through a UART port with hardware flow control.

Prepare NCP program:

Step 1: Create a project based on the example “ncp-uart-hw”;

Step 2: Enable “XNCP Library” plugin and disable “XNCP Stub Library” plugin;

Step 3: Enable callback “emberAfMainInitCallback”;

Step 4: Add a custom event:

Step 5: Save and generate the application;

Step 6: Open the file ncp-callback.c and add the following code snippet:

EmberEventControl customReportEventControl;
#define XNCP_CUSTOM_REPORT_HELLO_CMD  0xA0
void customReportEventHandler(void)
{
      uint8_t msg[32];
      msg[0] = XNCP_CUSTOM_REPORT_HELLO_CMD;
      sprintf(&msg[1], "Hello host!");
      emberAfPluginXncpSendCustomEzspMessage(sizeof(msg), msg);
      emberEventControlSetDelayMS(customReportEventControl, 5000);
}
/** @brief Performs any additional initialization required at system startup.
 *
 * This function is called when the application starts and can be used to
 * perform any additional initialization required at system startup.
 */
void emberAfMainInitCallback(void) {
 // your code here
      emberEventControlSetDelayMS(customReportEventControl, 5000);
}

Step 7: Build the project and download the generated image file to the WSTK.

Prepare host program: 

Step 1: Create a host project based on the example “Z3GatewayHost”;

Step 2: Enable callback “ezspCustomFrameHandler”;

Step 3: Modify Z3GatewayHost_callbacks.c :

#define XNCP_CUSTOM_REPORT_HELLO_CMD  0xA0
void ezspCustomFrameHandler(int8u payloadLength, int8u* payload)
{
      int8u cmd = payload[0];
      if (XNCP_CUSTOM_REPORT_HELLO_CMD == cmd) {
            emberAfCorePrintln("Ncp report:%s", &payload[1]);
      }
}

Step 4: Build the project.

Run and test:

Connect the WSTK to PC, then start Cygwin and run the host application. You can see custom message in the console of the host every 5 seconds:

$ ./Z3GatewayHost.exe -p COM9
Reset info: 11 (SOFTWARE)
ezsp ver 0x07 stack type 0x02 stack ver. [6.4.0 GA build 385]
Ezsp Config: set source route table size to 0x0064:Success: set
Ezsp Config: set security level to 0x0005:Success: set
Ezsp Config: set address table size to 0x0002:Success: set
Ezsp Config: set TC addr cache to 0x0002:Success: set
Ezsp Config: set stack profile to 0x0002:Success: set
Ezsp Config: set MAC indirect TX timeout to 0x1E00:Success: set
Ezsp Config: set max hops to 0x001E:Success: set
Ezsp Config: set tx power mode to 0x8000:Success: set
Ezsp Config: set supported networks to 0x0001:Success: set
Ezsp Policy: set binding modify to "allow for valid endpoints & clusters only":Success: set
Ezsp Policy: set message content in msgSent to "return":Success: set
Ezsp Value : set maximum incoming transfer size to 0x00000052:Success: set
Ezsp Value : set maximum outgoing transfer size to 0x00000052:Success: set
Ezsp Config: set binding table size to 0x0010:Success: set
Ezsp Config: set key table size to 0x0000:Success: set
Ezsp Config: set max end device children to 0x0020:Success: set
Ezsp Config: set aps unicast message count to 0x000A:Success: set
Ezsp Config: set broadcast table size to 0x000F:Success: set
Ezsp Config: set neighbor table size to 0x0010:Success: set
NCP supports maxing out packet buffers
Ezsp Config: set packet buffers to 255
Ezsp Config: set end device poll timeout to 0x0005:Success: set
Ezsp Config: set end device poll timeout shift to 0x0006:Success: set
Ezsp Config: set zll group addresses to 0x0000:Success: set
Ezsp Config: set zll rssi threshold to 0xFF80:Success: set
Ezsp Config: set transient key timeout to 0x00B4:Success: set
Ezsp Endpoint 1 added, profile 0x0104, in clusters: 8, out clusters 20
Ezsp Endpoint 242 added, profile 0xA1E0, in clusters: 0, out clusters 1
deactivate report event
Found 0 files
Z3GatewayHost>
Ncp report:Hello host!
Ncp report:Hello host!
Ncp report:Hello host!
Ncp report:Hello host!
Ncp report:Hello host!

答案

    芯科并没有提供具有天线分集的EFR32MG参考设计。但是，你可以以EM35x的天线分集设计作为例子，比如如何选用外部的RF开关。自EmberZNet 5.7.4 版本协议栈起，对发射/软件分集（当MAC—Level的ACK没有收到时切换天线路径）就开始有了支持，并且通过天线插件（Antenna plug-in）的选择/配置任何的GPIO都可用来做天线选择功能。接收/硬件分集（对到来的数据包的RSSI值做评估从而选择最强的路径）功能是不支持的。也就是说，在设计中通过MODEM_ANT0和MODEM_ANT1 两个GPIO选择 (在有两个天线选择GPIO和一个外部RF开关情况下)来保证发射/软件分集暂时可用，如果将来加入了接收/硬件天线分集功能，可以通过软件升级来支持该功能。请参考EFR32MG1规格书的表6.5来了解哪些GPIO具有MODEM_ANT0 和 MODEM_ANT1功能的详细内容。 
    就硬件的建议上，天线应该分开至少1/4波长的距离，而且应相互转成90度。请参考上述的EM35x天线分集设计作为例子。

英文原文：

      https://www.silabs.com/community/wireless/zigbee-and-thread/knowledge-base.entry.html/2016/11/09/how_can_i_implement-hsvn