Data Sheet
AC4790
Datasheet
https://www.lairdconnect.com/
14
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5.4 OEM Host Data Rate
The OEM Host Data Rate is the rate with which the OEM host and transceiver communicate over the serial interface. This rate
is independent of the RF rate, which is fixed at 76.8 kbps. Possible values range from 1200 bps to 115200 bps.
Note: Enabling Parity cuts throughput in half and the Interface Buffer size in half.
Table 5 lists supported asynchronous serial data formats.
Table 5: 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
5.5 Serial Interface Baud Rate
This two-byte value determines the baud rate used for communicating over the serial interface to a transceiver. Table 6 lists
values for some common baud rates. Baud rates below 1200 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 will be forced to 9600. The RF rate is fixed at 76.8kbps and is independent of the interface baud rate. For baud rate
values other than those shown in Table 6, the following equations can be used:
Table 6: Baud Rate / Interface Timeout
Baud Rate
BaudL (0x42)
BaudH (0x43)
Minimum Interface Timeout (0x58)
Stop Bit Delay (0x3F)
115200
0xFE
0x00
0x02
0xFF
57600
1
0xFC
0x00
0x02
0x03
38400
0xFA
0x00
0x02
0x08
28800
0xF8
0x00
0x02
0x0E
19200
0xF4
0x00
0x03
0x19
14400
0xF0
0x00
0x04
0x23
9600
0xE8
0x00
0x05
0x39
4800
0xD0
0x00
0x09
0x7A
2400
0xA0
0x21
0x11
0xFC
1200
0x40
0x21
0x21
0x00
2
1. 57600 is the default baud rate
2. 0x00 will yield a stop bit of 421µS. The stop bit at 1200 baud should actually be 833µS.