AeroComm Corporation AC4490 Benutzerhandbuch
S E R I A L I N T E R F A C E
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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. 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.
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 0x50 (80 bytes) and must be set to a minimum of 0x06 in
order to send the Enter AT Command mode command. To change the RF packet size from the default value, Auto
Config must be disabled and the appropriate Auto Config parameters must be changed.
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.
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 0x50 (80 bytes) and must be set to a minimum of 0x06 in
order to send the Enter AT Command mode command. To change the RF packet size from the default value, Auto
Config must be disabled and the appropriate Auto Config parameters must be changed.
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
Baud Rate
BaudL
(0x42)
(0x42)
BaudH
(0x43)
Minium Interface
Timeout (0x58)
Stop Bit Delay (0x3F)
115,200
0xFE
0x00
0x02
0xFF
57,600
1
1. 57,600 is the default baud rate
0xFC
0x00
0x02
0x03
38,400
0xFA
0x00
0x02
0x08
28,800
0xF8
0x00
0x02
0x0E
19,200
0xF4
0x00
0x03
0x19
14,400
0xF0
0x00
0x04
0x23
9,600
0xE8
0x00
0x05
0x39
4800
0xD0
0x00
0x09
0x7A
2400
0xA0
0x00
0x11
0xFC
1200
0x40
0x00
0x21
0x00
2
2. 0x00 will yield a stop bit of 421 uS. The stop bit at 1200 baud should actually be 833 uS.
BAUD
14.7456
6
×10
64
DesiredBaud
×
-----------------------------------------------
=
BaudH
Always 0
=
BaudL
Low 8 bits of BAUD (base 16)
=