TDK blu2i 用户手册

6 

 
Just as a telephony modem has control and status lines, the blu

2i

 Module 

also provides for 6 control and status lines as per the table below. The 
direction column is as seen from the modules viewpoint. 
 

IN or OUT 

CI also known as RI  (Ring Indicate) 

IN or OUT 

DCD (Data Carrier Detect) 

IN 

DSR (Data Set ready) 

OUT 

DTR (Data Terminal Ready) 

IN 

CTS (Clear to Send) 

OUT 

RTS (Request to Send) 

 
The first four lines are under program control and as such require GPIO 
pins and they are mapped to I/O as per the table below. The last two are 
under control of the UART driver and their functionality is always 
enabled. 
 

0 

IN/OUT 

GPIO1 

General Purpose I/O 

1 

IN/OUT 

GPIO2 

General Purpose I/O 

2 

IN/OUT 

UART_RI 

Input/Output from module 

3 

IN/OUT 

UART_DCD 

Input/Output from module 

4 

IN 

UART_DSR 

Input to Module 

5 

IN/OUT 

GPIO3/UART_DTR 

General Purpose I/O (or 
DTR functionality) 

6 

IN/OUT 

GPIO4 

General Purpose I/O 
(Right LED)  

7 

IN/OUT 

GPIO5 

General Purpose I/O (Left 
LED) 

 
Notes: 
 
1 

PIO4 (DSR) is used by the blu

2i

 module to sense that the host is 

connected, and is intricately linked with connections. For outgoing calls, 
if this line is not asserted then an error is immediately. Similarly for 
AT+BTP and AT+BTG. 
While in a call, for appropriate modes, a deassertion means fall into 
command state. If the deassertion exists for longer than the period 

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