ST STM32L4 5 Series - Figure 475. S1 Signal Coding; Figure 476. S2 Signal Coding

DocID024597 Rev 5 1491/1830
RM0351 Single Wire Protocol Master Interface (SWPMI)
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44 Single Wire Protocol Master Interface (SWPMI)
44.1 Introduction
The Single Wire Protocol Master Interface (SWPMI) is the master interface corresponding to
the Contactless front-end (CLF) defined in the ETSI TS 102 613 technical specification.
The principle of the Single wire protocol (SWP) is based on the transmission of digital
information in full duplex mode:
• S1 signal (from Master to Slave) is transmitted by a digital modulation (L or H) in the
voltage domain (refer to Figure 475: S1 signal coding),
• S2 signal (from Slave to Master) is transmitted by a digital modulation (L or H) in the
current domain (refer to Figure 476: S2 signal coding).
Figure 475. S1 signal coding
Figure 476. S2 signal coding
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