S42
Hardware User Guide
1VV0301303 Rev. 11
Page 19 of 85
2021-05-06
Not Subject to NDA
If I/O line availability at the host side is extremely tight, 2 I/O lines could be saved by using
the following scheme. This would come at the cost of
•
The host is not allowed to enter sleep mode.
•
The host must accept in coming data at all times and is not able to stop the
Sx sending data. This may be difficult to control for all scenarios and
adds the risk that data gets lost.
•
The
host doesn’t implement UICP, but wa
ke-up BT via GPIO
UART-TXD
GND
UART-RXD
IUC_IN# / CTS#
UART-RXD
UART-TXD
B
lu
eM
o
d
+
Sx
H
o
st
RTS#
CTS#
IUC_OUT# / RTS#
IUR_OUT#
IUR_IN#
BM+Sx-WKUP
Figure 7: 5-Wire (incl. GND) Interface supporting UICP (min. signals needed)
3.3.1.3.
Serial Interface without UICP Power Management
If power management with maintaining the operational environment is not necessary,
the serial interface could be designed with less I/O lines.
This saves 2 I/O lines at the cost that dynamic power management with maintaining the
operation environment cannot be used. UICP has to be disabled.
