Radiocrafts
Embedded Wireless Solutions
RC1xx0 / 2x00DK
2008 Radiocrafts AS RC1xx0 / 2x00DK Demonstration Kit version 3.0 User Manual (rev. 3.1)
Page 6 of 14
RS-232 interface
The Demonstration Board provides an RS232 driver circuit. The serial port is configured as a
data modem and a 1:1 cable should be used to connect the board to the PC.
The RTS/CTS handshaking pair is also provided, so that hardware handshaking may be used
on this port, but this is not enabled in the default configuration from the factory. Handshaking
can be enabled by changing the configuration in permanent memory, see RC232 User
Manual, and doing the following changes:
•
Remove jumper at P14
•
Insert jumpers at P13 to connect CTS and RTS to the RS232 driver
Figure 3: Enabling CTS and/or RTS handshake
P13 is used to set jumpers to connect the module UART interface to the RS232 PHY driver.
Normally the jumpers connecting RXD and TXD are installed, and provide UART
communication with a PC without handshaking. With the jumpers removed the modules RXD
and TXD can easily be connected to a host, for instance a microcontroller or external
development board. The table below shows the pinout and signals at P13.
Pin no.
Signal
Note
1
2
GND
3
4
CTS
Install jumper when using hardware handshake
5
6
RTS
Install jumper when using hardware handshake
7
8
CONFIG
9
10
TXD
Jumper installed from factory
11
12
RXD
Jumper installed from factory
13
14
GND
Note
: The module CTS is set up during the first stop bit sent to the module when the buffer is
full, and the host should then halt further character transmissions to prevent character loss. If
the host can not detect the CTS quickly enough during hardware handshake, it should be
configured for two stop bits.
Controlling CONFIG-mode via the RS232 port
The module can enter CONFIG-mode by toggling the RTS-signal from the host
(microcontroller or PC). By doing so, the Demonstration Board can act as a modem without
the need for manually or with other circuitry asserting the CONFIG-pin.
Modification procedure: On the bottom side of the PCB (layer 2), solder a connection between
Pin 7 and Pin 8 on P13 as seen in Figure 4, right picture, if required (the pins might already
be connected on newest PCB revisions). Then place the jumpers as shown in Figure 4, left
picture. Config-mode is now enabled when RTS signal is asserted low. RTS can normally be
controlled via various terminal-programs.
Remove jumper at P14 for
enabling CTS
Move jumpers at P13 to the
right for enabling CTS and RTS
