AC4868 868 MHz Transceiver
User’s Manual
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13
Laird Technologies
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www.lairdtech.com/ramp
OEM Host Data Rate
The OEM Host Data Rate is the rate with which the OEM Host and transceiver communicate over the serial
interface. Possible values range from 1200 bps to 57,600 bps.
Note: Enabling Parity cuts throughput in half and the Interface Buffer size in half.
supported asynchronous serial data formats.
Table 7: Supported Serial Formats
Data Bits
Parity*
Stop Bits Transceiver Programming Requirements
8
N
1
Parity Disabled
7
N
2
Parity Disabled
7
E,O,M,S
1
Parity Disabled
9
N
1
Parity Enabled
8
N
2
Parity Enabled
8
E,O,M,S
1
Parity Enabled
7
E,O,M,S
2
Parity Enabled
*Mark (M) corresponds to 1 & Space (S) corresponds to 0
Serial Interface Baud Rate
This two-byte value determines the baud rate used for communicating over the serial interface to a
transceiver. The Table below lists values for some common baud rates. Baud rates below 1200 and above
57600 baud are not supported. For a baud rate to be valid, the calculated baud rate must be within ±3% of
the OEM Host baud rate. If the Test pin (Pin 12) is pulled logic Low at reset, the baud rate is forced to 9600.
Baud
BaudL
(0x42)
BaudH
(0x43)
RF Baud (not
adjustable)
Minimum Interface
Timeout (0x58)
Stop Bit Delay
(0x3F)
57600
1
0xFC
0x00
28800
0x02
0x03
38400
0xFA
0x00
19200
0x02
0x08
28800
0xF8
0x00
28800
0x02
0x0E
19200
0xF4
0x00
19200
0x03
0x19
14400
0xF0
0x00
28800
0x04
0x23
9600
0xE8
0x00
19200
0x05
0x39
1. 57600 is the default baud rate.
Interface Timeout / RF Packet Size
Interface Timeout (EEPROM address 0x58), in conjunction with RF Packet Size (EEPROM address 0x5B),
determines when a buffer of data will be sent out over the RF as a complete RF packet, based on whichever
condition occurs first.
Interface Timeout – Interface Timeout specifies a maximum byte gap between consecutive bytes. When that
byte gap is exceeded, the bytes in the transmit buffer are sent out over the RF as a complete packet. Interface
Timeout is adjustable in 0.5ms increments and has a tolerance of ±0.5ms. Therefore, the Interface Timeout
should be set to a minimum of 2. The default value for Interface Timeout is 0x04 (2ms) and should be adjusted
accordingly when changing the transceiver baud rate.