6RS232 Modem Signals
Just as a telephony modem has control and status lines, the blu2i Module also provides for 6 control and status lines as per the table below. The direction column is as seen from the modules viewpoint.
Direction | Function |
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.
| PIO | Direction | Connector Pin Label | Function |
| Pin |
|
|
|
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:
1PIO4 (DSR) is used by the blu2i 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
24 of 36