AC4790-200A-485 Laird Technologies, AC4790-200A-485 Datasheet - Page 20

• Manufacturer Part Number: AC4790-200A-485
• Description: TXRX 900MHZ 3.3-5.5V FHSS 200MW
• Manufacturer: Laird Technologies
• Series: AeroCommr

Specifications of AC4790-200A-485

• Frequency: 902MHz ~ 928MHz
• Data Rate - Maximum: 115.2kbps
• Modulation Or Protocol: FHSS, FSK
• Applications: AMR, Fire & Security Alarms, Telemetry
• Power - Output: 5mW ~ 200mW
• Sensitivity: -110dBm
• Voltage - Supply: 3.3V, 5V
• Current - Transmitting: 68mA
• Data Interface: Connector, 2 x 10 Header
• Antenna Connector: On-Board, Chip
• Operating Temperature: -40°C ~ 85°C
• Package / Case: Module
• Wireless Frequency: 900 MHz
• Interface Type: 20-pin mini connector
• Board Size: 49 mm x 42 mm x 5 mm
• Modulation: FHSS, FSK
• Security: 1 byte System ID, DES
• Operating Voltage: 3.3 V to 5.5 V
• Output Power: 200 mW
• Antenna: Integral and External Dipole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Memory Size: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

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S E R I A L I N T E R F A C E
I N T E R F A C E T I M E O U T / R F P A C K E T S I Z E
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.
minimum of 2. The default value for Interface Timeout is 0x04 (2ms) and should be adjusted accordingly when
changing the transceiver baud rate.
RF Packet Size – When the number of bytes in the transceiver transmit buffer equals RF Packet Size, those bytes are
sent out as a complete RF packet. It is much more efficient to send a few large packets rather than several short
packets as every packet the transceiver sends over the RF contains extra header bytes which are not included in the
RF Packet Size. RF packet size can be set to a maximum of 0x80 and must be set to a minimum of 0x06 in order to
send the Enter AT Command mode command.
Baud Rate
1. 57,600 is the default baud rate
2. 0x00 will yield a stop bit of 421 uS. The stop bit at 1200 baud should actually be 833 uS.
115,200
57,600
38,400
28,800
19,200
14,400
9,600
4800
2400
1200
1
BaudL
(0x42)
0xFE
0xFC
0xFA
0xE8
0xD0
0xA0
T a b l e 7 : B a u d R a t e / I n t e r f a c e T i m e o u t
0xF8
0xF4
0xF0
0x40
BaudH
BaudL
(0x43)
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00
BAUD
=
BaudH
Low 8 bits of BAUD (base 16)
=
Minimum Interface
Timeout (0x58)
---------------------------------------------- -
64
=
×
14.7456
DesiredBaud
Always 0
0x02
0x02
0x02
0x02
0x03
0x04
0x05
0x09
0x11
0x21
×10
Therefore, the Interface Timeout should be set to a
6
Stop Bit Delay (0x3F)
0x00
0xFC
0xFF
0x03
0x08
0x0E
0x19
0x23
0x39
0x7A
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