S42 Hardware User Guide
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When using the TIO firmware and applications, call control can be supported by GPIO[4].
Driving GPIO[4] to logic High level during a data transfer phase will “hang up” the
connection and disconnect the Bluetooth link. This signal may be mapped to DSR, if an
RS232-style (DTE-type) interface is used. Please refer to S42\Central AT
Command Reference for a functional specification. GPIO[4] can be left unconnected if this
feature is not used.
3.3.1
4-Wire Serial Interface
If the host in question is sufficiently fast, a four-wire scheme may be successful. Connect the
serial lines UART-RXD, UART-TXD as well as UART-RTS# and GND; leave UART-CTS#
open. The host is required to stop sending data within a short time after de-assertion of
UART-RTS# (there is room for up to 4 more characters at the time RTS# drops).
Attention
: UICP has to be deactivated permanently in this configuration, because signal
UART-CTS# and IUR-IN# become inputs with no PU or PD if UICP is active. This would
cause floating CMOS inputs.
NOTE:
It is strongly recommended to use hardware flow control in both directions. Not using flow
control can cause a loss of data.