TDK blu2i User Manual

specified in S Register 519 then the connection is dropped as if an ATH 
command was received. 
 
2 

PIO2 (RI), is normally deasserted. When an incoming connection 

is detected it will be asserted, until the connection is either answered or 
rejected using ATA and ATH respectively. See S Registers 552 & 553 
for more details 
 
3 

PIO3 (DCD) will be deasserted when the device is in the 

unconnected state. Asserted when a connection is active. See S 
Registers 552 and 553 for more details. 
 
4 

PIO5 is either used as GPIO or driven as UART_DTR. When the 

unit is configured in pure host mode, this pin is forced into UART_DTR 
and is asserted when there is a Bluetooth connection. 
 
GPIO Pins 1,2,3,4 and 5 are available for general purpose use. 
 

 
The RFCOMM protocol used in Bluetooth for implementing the serial 
port profile allows for the exchange of four modem signals. This 
information is contained in a special transparent message which 
contains bits identified as RTR, RTC, DV and IC which depending on the 
type of serial device being emulated maps to DTR or DSR, RTS, DCD 
and RI respectively. In addition, this message also includes the ability to 
convey a BREAK input from one end to the other. 
 
So to allow for the greatest flexibility and variability in how the modem 
control signals are used out in the real world, S Registers 551, 552 and 
553 have been provided which allow for any of RTR,RTC,DV and IC to 
be mapped to any modem control/status line. 

 
If the host sends a break signal of duration greater than 100ms, then the 
blu

2i

 module is configured to treat that as a signal to perform a hardware 

reset. 
 
This being the case it is not possible to convey a BREAK over Bluetooth 
to the peer device. 

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