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MC33593 数据表(PDF) 5 Page - Motorola, Inc |
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MC33593 数据表(HTML) 5 Page - Motorola, Inc |
5 / 28 page MC33593 MOTOROLA SEMICONDUCTORS PRODUCTS 5 revision 7.0, 5 February 2002 © Motorola, Inc., 2002. COMMUNICATION PROTOCOL MANCHESTER CODING DESCRIPTION Manchester coding is defined as follows: data is sent during the first half-bit, complementary data is sent during the second half-bit. Figure 3: Manchester coding example The signal average value is constant. This allows clock recovery from the data stream itself. In order to achieve a correct clock recovery, Manchester coded data must have a duty cycle between: - 48% and 52% in OOK, - 45% and 55% in FSK. PREAMBLE, ID, HEADER WORDS AND MESSAGE DESCRIPTION The following description applies if the Data Manager is enabled (DME=1). The ID word is a Manchester coded byte whose content has been previously loaded in the Configuration Register 2. The complement of the ID word is recognized as an ID word. ID word is sent at the same data rate as data. A preamble is required: - before ID, - before Header if HE=1, - before data if HE=0. It enables: - in case of OOK modulation, AGC to settle, - in case of FSK modulation, data slicer reference voltage to settle, - in any case, clock recovery. Figure 4 defines the Preamble word in OOK and FSK modulation. Preamble content must be carefully defined in order not to be decoded as an ID or Header word. Figure 4: Preamble definition The Header word is a 4 bit Manchester coded message ‘0110’ or its complement sent at the selected data rate. This bit sequence and its complement must not be found in the sequence preamble and ID word. Data must follow the Header without any delay. Data are completed by a End-of-Message (EOM) word, consisting of 2 NRZ consecutive ones or zeroes. Even in case of FSK modulation, the data must be completed by a EOM and not by simply stopping the RF telegram. If the complement of the Header word is received, output data are complemented too. 0 0 0 11 1 0 Original data Manchester coded OOK Modulation: ‘0’ Manchester at data rate ‘1’ NRZ > 200µs i.e.: 2 ‘1’ NRZ at 9.6kBd, 1 ‘1’ NRZ at 4.8kBd AGC settling time Clock recovery ID FSK Modulation: Data slicer reference settling time ID 3 ‘1’ or ‘0’ Manchester at data rate ‘1’ or ‘0’ Manchester at data rate Clock recovery Freescale Semiconductor, Inc. For More Information On This Product, Go to: www.freescale.com |
类似零件编号 - MC33593 |
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类似说明 - MC33593 |
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