17
17
Pinout and I/O Description
17
4.3
COM Ports
The module provides four serial COM ports. Three of them (COM1 to COM3) support
RTS/CTS hardware flow control:
Pin Name
Type
Level
Description
Comment
TXD1
O
3V3_LVTTL
Serial COM1 transmit line (inactive state is high)
RXD1
I, PU
3V3_LVTTL
Serial COM1 receive line (inactive state is high)
RTS1
O
3V3_LVTTL
Serial COM1 RTS line.
The module drives this pin low when
ready to receive data
CTS1
I, PU
3V3_LVTTL
Serial COM 1 CTS line.
Must be driven low when ready to
receive data from the module.
TXD2
O
3V3_LVTTL
Serial COM2 transmit line (inactive state is high)
RXD2
I, PU
3V3_LVTTL
Serial COM2 receive line (inactive state is high)
RTS2
O
3V3_LVTTL
Serial COM2 RTS line.
The module drives this pin low when
ready to receive data
CTS2
I, PU
3V3_LVTTL
Serial COM3 CTS line.
Must be driven low when ready to
receive data from the module.
TXD3
O
3V3_LVTTL
Serial COM3 transmit line (inactive state is high)
RXD3
I, PU
3V3_LVTTL
Serial COM3 receive line (inactive state is high)
RTS3
O
3V3_LVTTL
Serial COM3 RTS line.
The module drives this pin low when
ready to receive data
CTS3
I, PU
3V3_LVTTL
Serial COM3 CTS line.
Must be driven low when ready to
receive data from the module.
TXD4
O
3V3_LVTTL
Serial COM4 transmit line (inactive state is high)
RXD4
I, PU
3V3_LVTTL
Serial COM4 receive line (inactive state is high)
Unused COM-port signals can be left floating. Flow control is disabled by default.
The COM port settings (baud rate, flow control, etc) are set with the
setCOMSettings
user
command. The maximum baud rate is 4Mbits/s.
The LVTTL RXD and CTS inputs of the module shall not be driven while its VDD_3V3 input
supply is not present.
4.3.1
Typical Application
An example of a circuit to convert the COM1 signals to RS232 level is shown below. In
green, the signals to be connected to the mosaic pins. The RTS1 and CTS1 signals can be
left unconnected if hardware flow control is not required.
It is recommended to use the same 3V3 source to supply the RS232 transceiver and the
VDD_3V3 pins of the module, to ensure that the transceiver outputs are not driven when
the module is not powered.
