Proprietary Knowledge Base

      • PCB number of layers vs Output power

        dasimon | 08/229/2017 | 07:33 AM

        Using a 2-layer PCB in the application hardware is usually preferred by customers due to cost saving purposes. Still, based on the RF output power level, unwanted radiation of top or bottom layer traces (mostly VDD or digital) can occur, which causes that the application can violate the harmonic limits of the related standards. In order to minimize the possibility of unwanted trace radiations, Silicon Labs recommends to use multilayer PCBs in the following cases:


        • >=16dBm output power at sub-GHz frequencies
        • >=10dBm output power at 2.4GHz

        Note that the actual recommendation depends on which standard (ETSI, FCC, ARIB, etc.) the application has to be compliant with.


        One can notice that not all Silicon Labs reference design follows the above listed recommendations. EZRadioPRO reference design boards are made on 2 or 4 PCB layers based on the output power, while all EZR32 and EFR32 reference design boards are using 4 or 6 PCB layers due to the complexity of the design. In the latter case, the layout routing could not be realised on a 2-layer PCB if all digital traces were intended to be used. Of course, on a custom design where the complexity of the design is much less, 2-layer PCBs can be used for EZR32 or EFR32 applications as well considering the above listed recommendations.

      • 如何使用Network rejoin加入网络?

        Lesun | 08/218/2017 | 10:39 PM



        设备如何使用Network rejoin方式加入网络?



        本文主要讲解设备在拥有网络信息的情况下,如何通过NWK rejoin的方式入网。通常可通过外部的方式将网络信息传送给某设备节点,该设备节点获取所需要的网络信息后,直接通过NWK rejoin加入网络。此时该网络不需要处于允许设备入网状态(即PJoin状态未开启也可以入网)。下面通过一个例子来讲解该过程。本实验使用两块WSTK+4151radio板。


        首先,将UART Bootloader以及NCP firmware烧录一个4151radio板。将板子连接电脑,使用Simplicity Command进行烧录,在CM中输入如下命令:


        C:\Users\Lesun>commander flash C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v1.1\protocol\zigbee_5.10\ncp-images\efr32mg1p232f256gm48\ncp-uart-rts-cts-use-with-serial-uart-btl-5.10.1.s37 C:\SiliconLabs\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v1.1\protocol\zigbee_5.10\tool\bootloader-efr32mg1p232f256gm48\serial-uart-bootloader\serial-uart-bootloader.s37


         其次,在Cgywin中编译Z3Gateway sample,并运行Host程序,使用如下命令建立网络。使用info CLI命令查看当前网络信息,在下一步设备加入网络时需要用到,包括网络PANID、信道、Network Key等,如下图所示。在Host端输入keys print可以查看该网络的Network Key。




        然后,使用Z3Light sample作为基础示例,在其Z3LightSOC_callback.c上增加如下核心代码:


        EmberStatus MyNodeSecurityInit()
                 EmberInitialSecurityState state;
                 EmberStatus status;
                 EmberKeyData NetworkKey = {0x58,0x12,0x17,0x34,0x64,0xC7,0x7A,0xDC,0x40,0xD9,0x39,0x01,0xFB,0xD0,0xF4,0xAE,};
                 MEMSET(&state, 0, sizeof(EmberInitialSecurityState));
                 state.bitmask |= EMBER_HAVE_NETWORK_KEY;
                 emberAfSecurityPrintln("set state to: 0x%2x", state.bitmask);
                 status = emberSetInitialSecurityState(&state);
                 if (status != EMBER_SUCCESS) {
                   emberAfSecurityPrintln("security init node: 0x%x", status);
                   return status;
                 return EMBER_SUCCESS;


        void findingAndBindingEventHandler()
        #if 0
          if (emberAfNetworkState() == EMBER_JOINED_NETWORK) {
            emberAfCorePrintln("Find and bind target start: 0x%X",
               EmberStatus status = EMBER_INVALID_CALL;
               EmberNodeType nodeType = EMBER_ROUTER;
               EmberNetworkParameters networkParams;
               MEMSET(&networkParams, 0, sizeof(EmberNetworkParameters));
               networkParams.radioChannel = 25;
               networkParams.radioTxPower = 8;
               networkParams.panId = 0x08B6;
               networkParams.joinMethod = EMBER_USE_NWK_REJOIN_HAVE_NWK_KEY;
               status = MyNodeSecurityInit();
               emberAfCorePrintln("MyNodeSecurityInit status = 0x%X", status);
               status = emberJoinNetwork(nodeType, &networkParams);
               emberAfCorePrintln("%ping on ch %d, panId 0x%2X.  status = 0x%X",
                                                    networkParams.panId, status);



        最后,将Bootloader以及编译生成的应用程序烧录另一个4151radio板,按下WSTK地板上任何一个按键,可以看到该设备成功加入刚才建立的网络。输入info CLI命令可以查看该设备的网络信息,如下图所示。



        总结:以上主要介绍一种out-of-band的实现方式。当设备获取网络参数之后,可以通过NWK rejoin加入网络,即通过调用emberJoinNetwork()以及在此之前调用emberSetInitialSecurityState()来实现。其中需要将安全状态的bitmask 设置为EMBER_HAVE_NETWORK_KEY,并设置正确的网络Key。