RL78/F13, F14 CHAPTER 17 LIN/UART MODULE (RLIN3)
R01UH0368EJ0210 Rev.2.10 1215
Dec 10, 2015
(2) Wake-up Reception
The detection of a wake-up signal involves the use of an input signal low width count function.
The input signal low width count function measures the low width of the input signal to the LRXDn pin, using the same
sampling point as data reception. The function can measure the input signal low width of 2.5 Tbits of fLIN or greater.
In LIN master mode, appropriately setting the LWBR0 bit in the LWBRn register allows switching between LIN operation
mode and LIN wake-up mode without changing any baud rate generator setting.
Set the LWBR0 bit in the LWBRn register to 0 when LIN Specification Package Revision 1.3 is used, and set it to 1 when
LIN Specification Package Revision 2.x is used. When the LWBR0 bit is set to 1, fa is always selected as the LIN system
clock (f
LIN) regardless of the setting of LCKS bits in the LMDn register (setting of LCKS bits not affected).
Setting the baud rate to 19200 bps with fa selected allows 130 s or longer low level width of the input signal to be detected
regardless of the setting of LCKS bits in the LMDn register.
When using this function, in LIN wake-up mode, set the RFT bit in the LDFCn register to 0 (LIN master mode: reception), or
RCDS bit to 0 (LIN slave mode: reception), and the FTS bit in the LTRCn register to 1 (LIN master mode: frame transmission
or wake-up transmission/reception started; LIN slave mode: header reception or wake-up transmission/reception started).
When the low width to be measured is reached, the FRC flag in the LSTn register turns 1 (successful response/wake-up
reception). If the FRCIE bit in the LIEn register is 1 (successful response or wake-up reception interrupt enabled), an interrupt
request is generated.
Figure 17-19. Input Signal Low Count Function
Wake-up detection
width (2.5 Tbits)
LRXDn
(n = 0, 1)
FRC bit in
LSTn register
Timing for setting the FRC
bit in the LSTn register
(3.0 Tbits)
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