User's Manual

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ELS31-VA/ELS51-VA Hardware Interface Description
2.1 Application Interface
56
ELS31-VA_ELS51-VA_HID_v01.000 2017-01-04
Confidential / Preliminary
Page 44 of 106
Figure 20 shows the described RING0 wake up mechanism:
RING0 shall be high
After a given programmable timeout with no activity on ASC0, RTS0 will be driven high and
the host will fall asleep if RING0 remains high (note: Host shall wait at least for one UART
character after RTS0 is driven high before entering sleep mode, to catch the last potential
character transmission over UART)
The module will wake-up the host driving RING0 from high to low
The Host will inform the module it is ready to receive over UART by driving RTS0 to low
Figure 20: Wake-up via RING0
RING0
Host wake-up event by
module
Host is ready to receive
over UART
RTS0
Host enters sleep mode