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KRX416 数据表(PDF) 3 Page - Radiometrix Ltd |
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KRX416 数据表(HTML) 3 Page - Radiometrix Ltd |
3 / 5 page Radiometrix Ltd KRX416 page 3 Function S0 =1 Message repeated.... 150ms: end of message 240ms: function activated Start of new message S0 Output RXD Notes: 1. Absolute maximum source/sink current from each S0-S3, LED-L, LED-V pins is 25mA. 2. Output pulse length is between 10 and 12ms 3. Can be held high or low. When high, the outputs S0-S3 will be active only for a brief period (see note 2), even if the same message continues to be received over and over again – this is intended as a control pulse for interfacing to additional logic or a microcontroller and is the most basic and secure way to use the decoder. When low, the outputs will be active for 350-500ms (approx.) and this long period allows “refreshing” by repeat messages from the same transmitter. In this way, repeated transmissions with the same code (e.g. a user holding down a function-code button at the transmitter) will cause the respective decoder output also to stay active, until the message ceases to be received within the 350-500ms window. The function-code may change (i.e. be added to) but the outputs will not be cleared until reception of the message has ended. Data from a code-hopped message Transmission format is 1250bps (nominal rate) Manchester encoding. Although the function-code is only 4 bits, total message length is 67 bits. This includes a 28-bit serial number and a 32-bit encrypted hop-code. Note that the serial number and function code data is not encrypted. The correct status of the transmission is used to validate the data. This is achieved through use of the ever changing hop- code (changes for every new message) and by synchronising the KRX416 IC to the transmitter(s) in use. Put another way: the KRX416 “Learns” individual unique transmitters, as required by the user. The hop-code is encrypted using the serial number of the transmitter plus the manufacturer code (64- bit), which is kept secret and is not transmitted. The function-code (S0-S3) appears twice in the message and forms a part of the hop-code encryption process. If the KRX416 loses synchronisation with the transmitter (e.g. repeated transmitter activation whilst out of range of the receiver) then the transmitter must be activated twice with valid and sequential hop- codes before KRX416 will allow the control to be processed. The hop-code is only valid if it is within a forward window of +32768 activations. This mechanism prevents “code-grabbers” from breaking the security of the system by recording and re-broadcasting old codes. Additionally, in the KRX416 a window exists allowing up to 14 transmissions to occur whilst the transmitter is out of range before two valid sequential transmissions are required to use the system. In practice a user may not notice the latter, since human reaction to the unsuccessful attempt is simply to “press the button again”. The level of redundancy and encryption in a message mean that, in simple terms, the KRX416 will only output a function-code that has been received from a properly recognised and synchronised transmitter. Figure 3: Timing diagram – showing action upon receiving a message with S0 = 1 In a typical set-up, the time delay between “button-press” at the transmitter and function activation by the KRX416 IC at the receiver is approx. ¼s. |
类似零件编号 - KRX416 |
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类似说明 - KRX416 |
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