FIFO DATA PACKETS
Symmetricom, Inc.
bc620/627AT Time and Frequency Processor
4-11
4.1.13 PACKET “O” - REQUEST DATA FROM THE bc620/627AT
This packet is used to request data from the TFP which is not available via the register interfaces.
It was added primarily to allow the user to verify the integrity of the programmed setup data.
This packet has been created with a very extensible format, and additional data will be made
available as customer needs and suggestions are addressed.
The TFP signals a packet ready condition by setting bit2 in the ACK register. It is the
responsibility of the host to clear this bit by writing to the ACK register with bit2 set.
Note
: The user is advised against repetitively issuing Packet “O” to the TFP. Processing
overhead is introduced to the TFP on-board CPU which could momentarily disrupt time
keeping.
The packet format follows:
REQUEST FORMAT
byte
1
SOH.
byte
2
“O”
(Upper case letter).
byte
3
“0” or “1” or “2.”
byte
4
ETB.
RESPONSE FORMAT “0” REQUEST RTC TIME (see Packet “L”')
byte
1
SOH.
byte
2
“o”
(Lower case letter).
byte
3
“0”
(ASCII zero).
byte
4
Years Tens.
byte
5
Years Units.
byte
6
Months Tens.
byte
7 Months
Units.
byte
8
Day of Month Tens.
byte
9
Day of Month Units.
byte
10
Hours Tens.
byte
11
Hours Units.
byte
12
Minutes Tens.
byte
13
Minutes Units.
byte
14
Seconds Tens.
byte
15
Seconds Units.
byte
16
ETB.
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