Proprietary Knowledge Base

    Publish
     
      • MANCHESTER decoding

        zopapp | 04/119/2015 | 10:04 AM

        Question

        What happens if Manchester decoding encounters invalid bit pairs on Si4x6x/5x?

        Answer

        During the reception of a MANCHESTER encoded bit stream it is conceivable (especially around sensitivity level) that some of the bits are corrupted so they no longer form a valid MANCESTER encoded bit pair (01 or 10) with their neighbors. A question can be raised quite rightly: how does the packet handler decode such corrupted bit patterns?

         

        The answer is if the packet handler MANCHESTER decoding algorithm encounters an invalid bit pair (00 or 11) it will decode it as per the result of the last (most recent) valid bit pair. As an example let’s assume the following MANCHESTER coding map and encoded data sequence:

         

        1              ->            10

        0              ->            01

        Data_sequence:     0101 1010 1001 0110

         

        If the data has been received correctly the decoded sequence will look like this: 0011 1001. Now, let’s corrupt the data stream at random locations:

         

        Data_corrupted1:            0101 1011 1001 0110

        Decoded pattern1:          0011 1001 (Note, that the decoded sequence is still correct)

         

        Data_corrupted2:            0101 1010 1000 0110

        Decoded pattern2:          0011 1101 (Note, that the error propagates through the decoded stream)

         

        What if there is no previous valid pattern to take the decoded symbol from at invalid bit pair cases. This can happen if the 1st bit pair to be decoded is not valid to start with. In such a scenario the invalid bit patterns will always decode as a 0 symbol regardless of the code map. Let’s have a look at such a scenario!

         

        Data_corrupted3:            1101 1010 1001 0110

        Decoded pattern2:          0011 1101

         

        And finally one important note regarding the topic: the packet handler will never issue a signal saying that there has been a MANCHESTER bit pattern violation in the received data stream, nor will it abort the reception of such a packet. It will simply keep on decoding the data stream with above rules as long as the desired number of bytes have been fully received.

         

        Note also that the CRC error calculation is always done on the decoded bit sequence. So it may as well happen that there are errors in the MANCHESTER coded received bit pattern, but after decoding the errors will not show any longer (see pattern1 above) and there will not be a CRC error.

      • 针对多种无线M-Bus标准的一站式解决方案

        EllenTang | 04/117/2015 | 02:46 AM

        开放的无线 M-Bus 协议为智能计量和智能电网应用提供了已经验证并易于部署的无线连接解决方案。
        基于 EN13757-4/3 欧洲标准,无线 M-Bus 规定了智能通用仪表、数据集中器、移动抄表设备和热分配表之间无缝的 sub-GHz RF 通信协议。

        Wireless M-Bus_1.png

         

        水、气和热表这些无线智能仪表应用需要长时间电池使用寿命,为满足这种需求,无线 M-Bus 协议规定了只需要耗费很小的表间通讯数据量,从而使得电池寿命可以长达 15-20 年。
        通过过去几年中在许多国家大量的现场测试和部署,无线 M-Bus 在欧洲已经成为被广泛接受的智能计量通信标准。
        Wireless M-Bus_2.png

        软件堆栈架构


        Silicon Labs (芯科科技) 无线M-Bus解决方案包括软件堆栈和硬件设备。堆栈机构包括
         

        • 到应用或数据链层的API访问
        • 针对MCU配置的开放HAL
        • 运行时PHYAPI配置
        • 针对M0+M3 M4 ARM内核的APL, DLL+, DLL层(核心协议栈功能)的预编译库
        • 在演示应用中配置仪表或集中器的 PC 工具
        • 用于调试的WM-Bus嗅探器(需要单独的嗅探器硬件)

         

        无线M-Bus硬件
        001.jpg

         

        Silicon Labs EZR32是一款单芯片无线MCU解决方案,具有868 MHz频段下+13 dBM输出功率和169 MHz频段下+20 dBM输出功率。也包括了169 MHz频段下+27 dBM输出功率配置的设计文件。
        更多信息,敬请访问Silicon Labs 官网Wireless M-Bus页面详细了解.

      • Silicon Labs推出业内首款完整的无线M-Bus解决方案

        EllenTang | 04/111/2015 | 05:09 AM

        wireless-mbus-press-image.jpg

        Silicon Labs针对欧洲市场推出业内首款完整的无线M-Bus解决方案

         

        整合无线M-Bus协议栈、入门开发套件、以及丰富的无线MCU、收发器和32MCU选项的智能计量平台解决方案

         

        中国,北京-20154-物联网(IoT)领域中无线连接解决方案的领先供应商Silicon Labs(芯科科技有限公司,NASDAQ:SLAB)今日宣布针对欧洲市场推出业内首款完整的无线M-Bus平台解决方案,设计旨在简化面向电、气、水和热资源的无线可连接智能仪表的开发。Silicon Labs完整的智能计量解决方案包括无线M-Bus软件协议栈和无线入门开发套件,有效加快产品上市速度。此无线M-Bus解决方案结合了Silicon Labs广泛的产品线,包括节能型基于ARM®内核的单片机(MCU)和sub-GHz无线IC,并且支持欧洲智能计量标准的所有模式,其中也包括普遍的169MHz N模式。

         

        开放的无线M-Bus协议为智能计量和智能电网应用提供了已经验证并易于部署的无线连接解决方案。基于EN13757-4/3欧洲标准,无线M-Bus规定了智能通用仪表、数据集中器、移动抄表设备和热分配表之间无缝的sub-GHz RF通信协议。水、气和热表这些无线智能仪表应用需要长时间电池使用寿命,为满足这种需求,无线M-Bus协议规定了只需要耗费很小的表间通讯数据量,从而使得电池寿命可以长达15-20年。通过过去几年中在许多国家大量的现场测试和部署,无线M-Bus在欧洲已经成为被广泛接受的智能计量通信标准。

         

        作为目前市场上最完整的无线M-Bus解决方案,Silicon Labs的无线M-Bus平台解决方案覆盖了欧洲所有区域的特殊需求。其软件协议栈兼容无线M-Bus规范(EN13757-4)、无线M-Bus应用层(EN13757-3)和开放式计量系统(OMS)工作组的应用层。此外,该协议栈支持868MHz和169MHz从物理层到应用层的各类模式。所支持的模式包括T1、T2、S1、S1-M、S2、C1、C2、N1和N2(a-g),同时带有针对N模式的超快前导符检测能力,并且不减损RF性能。

         

        Silicon Labs公司副总裁兼微控制器和无线产品总经理Daniel Cooley表示:“作为物联网领域中sub-GHz连接解决方案的领导厂商,Silicon Labs已经针对欧洲计量市场研发出经过现场验证的无线M-Bus专业技术。我们把在智能计量应用领域的专业知识融入到业内最完整、基于标准的无线M-Bus平台解决方案之中,这可使开发人员能够简化并加速他们的智能仪表设计,在整个欧洲范围内进行快速部署。”

         

        无线M-Bus平台解决方案针对模块化和扩展性、高RF性能、超低功耗和小存储空间进行了优化,根据采用的模式和设备类型不同,有的程序Flash空间可小至32KB。软件协议栈为应用和扩展数据链层提供了便捷的基于应用程序编程接口(API)的访问方法。该协议栈也包括可选的串行通信接口,这使得可以通过外部主机处理器进行无线M-Bus软件控制。不同于竞争对手的解决方案,Silicon Labs的无线M-Bus平台使用硬件AES加密引擎为计量系统提供安全保障。

         

        无线M-Bus解决方案的模块化架构具有完全开放的硬件抽象层(HAL),这使开发人员能够灵活选择最佳的Silicon Labs MCU和sub-GHz RF器件,满足客户计量应用对于性能、成本和尺寸的各类需求。对于Silicon Labs的32位EZR32 sub-GHz无线MCU,以及EZRadioPRO sub-GHz RF收发器和全部32位EFM32 Gecko MCU产品系列,都有相应的无线M-Bus软件,以bin或obj格式给出。

         

        无线M-Bus软件包包括快速入门指南、完整的API文档、预编译库(针对ARMCortex-M0+、M3和M4内核)和在演示应用中配置仪表或集中器的PC工具。Silicon Labs提供EZR32入门开发套件,特别针对开发人员所希望的868MHz(SLWSTK6220A)和169MHz(SLWSTK6224A)频段进行了优化。无线M-Bus快速启动指南为开发人员提供了启动计量应用设计所需的所有基本信息。Silicon Labs也提供了额外的无线M-Bus设计文件,包括原理图、物料清单(BOM)以及布局布线图,其中也包括针对意大利市场+27dBm输出功率设计。

         

        价格及供货

        计量系统开发人员能够从Silicon Labs的官方网站上免费下载无线M-Bus软件协议栈。SLWSTK6220A和SLWSTK6224A EZR32入门开发套件现已可供使用,价格均为299美元。有关Silicon Labs无线M-Bus平台解决方案的更多信息、下载软件协议栈和快速启动指南或者订购入门开发套件,请访问网站:www.silabs.com/wirelessmbus

         

        关于Silicon Labs

        Silicon Labs公司(NASDAQ:SLAB)是在物联网、互联网基础设施、工业控制、消费电子和汽车等市场领域中领先的芯片、软件和系统解决方案提供商。我们解决电子行业各项难题,在性能、节能、互联和简约设计方面为客户带来显著优势。Silicon Labs拥有世界一流的具有卓越软件和混合信号设计经验的工程团队,提供设计人员把最初想法快速、简便的转化为最终产品所需的工具和技术。有关Silicon Labs公司的更多信息,请浏览网站:www.silabs.com

      • Si446x state transition time

        zopapp | 04/99/2015 | 05:53 AM

        Question

        Can I have fixed state transition times on Si446x?

        Answer

        The short answer is, yes you can *for entering into Tx State* from any other (valid) states. This sort of fixed transition times come handy in time synchronized systems where the desired packet has to be transmitted in a fixed time with regards to a reference time instant.

         

        By default the SI446x RFIC family enters into Tx state as fast as it can. However, the time required to process the START_TX command may not be fixed due to some overhead activates (e.g., running of interrupt service routines) in the command handler.

         

        There is a mode of operation where the transition times to Tx states are fixed, albeit longer than in the default (as fast as possible) configuration. To make this operation active clear field “SEQUENCER_MODE” in API property “GLOBAL_CONFIG” (for more information on the API property please refer to the API documentation). This mode of operation will have guaranteed and consistent transition times to Tx from the following device states:

         

        SLEEP/SPI_ACTIVE                              500 cycles

        TX_TUNE                                               75 cycles

        READY                                                   150 cycles

        RX                                                          150 cycles

         

        One cycle in the above chart means 30 times the reference clock time period. With a 30 MHz reference clock one cycle is 1us. The time periods in above table measure from the nSEL signal going up at the end of the START_TX command.

         

        *Note: At the Rx side during reception a consistent reference point in time is (only) sync word detection. Time synchronized applications may make use of this.