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©
2019 Radiocrafts AS
RC232 User Manual (ver 2.01)
RC232 USER MANUAL
The module has an internal buffer of 128 or 1024 bytes that determines the maximum length of the RF packet
(over-the-air). The maximum UART packet length is determined by this limit, but also by addressing mode and
CRC enabled/disabled.
Table 3
– Maximum UART packet length (default setting highlighted)
No
addressing
2byte
addressing
4byte
addressing
CRC
enabled
RC12xx
RC17xx(HP)
RC11xx(HP)
RC25xx(HP)
✔
✘
✘
✘
127
1023
✔
✘
✘
✔
125
1021
✘
✔
✘
✘
125
1021
✘
✔
✘
✔
123
1019
✘
✘
✔
✘
N.A.
1015
✘
✘
✔
✔
N.A.
1013
The PACKET_LENGTH configuration parameter is default set to 128 (0x80).
2.4 UART Flow control
Normally no flow control (handshake) is used. Any microcontroller with hardware or software UART or UART
converter communicating with the module in its configurable UART speed can be used to communicate with the
module.
Optionally the CTS and/or RTS/RXTX can be used for hardware flow control:
CTS pin
– Clear to send: The low-asserted CTS pin provides flow control for the module. When CTS is asserted
(low), serial data can be sent to the module for RF transmission. If the module is busy, like during RF data
transmission or reception, the CTS pin will be de-asserted (high) to stop any data transfer to the module.
RTS pin
– Ready to send: When RTS is asserted (low) the host allow data to be sent from the module to the host.
The host can stop the module from sending data by de-asserting (high) the RTS signal. Note that if the module has
data waiting in the receive buffer, it will not be able to receive or transmit further data until the RTS has been
asserted and the data in the buffer is transferred to the host.
RXTX pin
– RS485 driver control: RXTX is low when the module can receive data on RXD. RXTX is high when the
module is transmitting data on TXD and additionally 5 ms for the module to turn from TXD to IDLE mode (see
Timing Information in the module data sheet). The RXTX pin is normally connected to the /RE and DE pins on the
RS485 driver circuit.
The configuration of the flow control for the UART interface is done by changing UART_FLOW_CTRL in the non-
volatile configuration memory.
Note!
The module CTS is set up during the first stop bit sent from to module when the buffer is full, and the host
should then halt further character transmissions to prevent character loss. If the host cannot detect the CTS quickly
enough during hardware handshake, it should be configured for two stop bits.
