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LT2510 User’s Manual
T H E O R Y O F O P E R A T I O N
LAIRD TECHNOLOGIES www.lairdtech.com
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 – Interface Timeout specifies a maximum byte gap between consecutive bytes. When that byte gap is
exceeded, the bytes in the transmit buffer are processed as a complete packet. Interface Timeout (EEPROM address 0x58), in
conjunction with the RF Packet Size, 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 is adjustable in 200us increments and should be equal to or greater than two
full bytes times. The minimum Interface Timeout is 0x02.
exceeded, the bytes in the transmit buffer are processed as a complete packet. Interface Timeout (EEPROM address 0x58), in
conjunction with the RF Packet Size, 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 is adjustable in 200us increments and should be equal to or greater than two
full bytes times. The minimum Interface Timeout is 0x02.
RF Packet Size - RF Packet Size is used in conjunction with Interface Timeout to determine when to delineate incoming data as
an entire packet based on whichever condition is met first. When the transceiver receives the number of bytes specified by RF
Packet Size (EEPROM address 0x5A) without experiencing a byte gap equal to Interface Timeout, that block of data is processed
as a complete packet. Every packet the transceiver sends over the RF contains extra header bytes not counted in the RF Packet
Size. Therefore, it is much more efficient to send a few large packets than to send many short packets. The maximum RF Packet
Size is 239 bytes, or 0xEF, at 500kkbps RF Data Rate and 96 bytes, or 0x60, at 280kbps RF Data Rate.
an entire packet based on whichever condition is met first. When the transceiver receives the number of bytes specified by RF
Packet Size (EEPROM address 0x5A) without experiencing a byte gap equal to Interface Timeout, that block of data is processed
as a complete packet. Every packet the transceiver sends over the RF contains extra header bytes not counted in the RF Packet
Size. Therefore, it is much more efficient to send a few large packets than to send many short packets. The maximum RF Packet
Size is 239 bytes, or 0xEF, at 500kkbps RF Data Rate and 96 bytes, or 0x60, at 280kbps RF Data Rate.
F L O W C O N T R O L
Although flow control is not required for transceiver operation, it is recommended to achieve optimum system performance and to
avoid overrunning the LT2510’s serial buffers. The LT2510 uses separate buffers for incoming and outgoing data.
avoid overrunning the LT2510’s serial buffers. The LT2510 uses separate buffers for incoming and outgoing data.
R X D D a t a B u f f e r a n d C T S
As data is sent from the OEM Host to the radio over the serial interface, it is stored in the LT2510’s buffer until the radio is ready
to transmit the data packet. The radio waits to transmit the data until one of the following conditions occur (whichever occurs
first):
to transmit the data packet. The radio waits to transmit the data until one of the following conditions occur (whichever occurs
first):
•
The RF packet size is reached (EEPROM address 0x5A)
•
An Interface Timeout occurs (EEPROM address 0x58)
The data continues to be stored in the buffer until the radio receives an RF Acknowledgement (ACK) from the receiving radio
(addressed mode), or all transmit retries/broadcast attempts have been utilized. Once an ACK has been received or all
retries/attempts have been exhausted, the current data packet is removed from the buffer and the radio will begin processing the
next data packet in the buffer.
(addressed mode), or all transmit retries/broadcast attempts have been utilized. Once an ACK has been received or all
retries/attempts have been exhausted, the current data packet is removed from the buffer and the radio will begin processing the
next data packet in the buffer.
To prevent the radio’s RXD buffer from being overrun, it is strongly recommended that the OEM Host monitor the radio’s CTS
output. When the number of bytes in the RXD buffer reaches the value specified by CTS_ON (EEPROM address 0x5C - 0x5D),
the radio de-asserts (High) CTS to signal to the OEM Host to stop sending data over the serial interface. CTS is re-asserted after
output. When the number of bytes in the RXD buffer reaches the value specified by CTS_ON (EEPROM address 0x5C - 0x5D),
the radio de-asserts (High) CTS to signal to the OEM Host to stop sending data over the serial interface. CTS is re-asserted after
E N G I N E E R ’ S T I P
•The LT2510 supports a majority of standard as well as non-standard baud rates. To select a standard baud rate,
use the value shown for EEPROM address 0x42 in Table 6 above. To enable a non-standard baud rate, program
EEPROM address 0x42 (Custom Baud Enable) to 0xE3 and then use the equation above to solve for BAUD_M
and BAUD_E.
•Adjusting the Serial Interface Baud Rate does not affect the RF data rate.
•The Interface Timeout and RF Packet Size will be set automatically based on the Interface Baud Rate if the
Auto Config option is enabled.
use the value shown for EEPROM address 0x42 in Table 6 above. To enable a non-standard baud rate, program
EEPROM address 0x42 (Custom Baud Enable) to 0xE3 and then use the equation above to solve for BAUD_M
and BAUD_E.
•Adjusting the Serial Interface Baud Rate does not affect the RF data rate.
•The Interface Timeout and RF Packet Size will be set automatically based on the Interface Baud Rate if the
Auto Config option is enabled.