FM6124 Ramtron Corporation, FM6124 Datasheet - Page 17

• Manufacturer Part Number: FM6124
• Description: Event Data Recorder With F-ram
• Manufacturer: Ramtron Corporation

Since the EDR's I
it is unnecessary to send the subsequent address for each
byte read from the buffer. It is also unnecessary to begin
reading at address 0x2C.
automatically place the next event pointed to by SP into
the read buffer, you must read address 0x33. With this
single exception, the user is free to retrieve event data from
the read buffer as best suits their application.
If the multiple event read command issued was a
STREAMING GET, then RP will be incremented or
decremented as indicated by DIR.
If the multiple event read command issued was a
STREAMING GET KEEP, then RP will remain
unchanged.
Event Skipping Command
The SKIP Command (0101) can be used to increment RP
(DIR = 0) or decrement RP (DIR = 1). Note that RP will
always stay at least one Event before WP and that it will
never be decremented “below” FP.
FIRST and LAST Commands
With the FIRST command, the user can move RP to the
oldest Event immediately (RP = FP)
With the LAST command, the user can move RP to the
newest Event immediately (RP = WP -1)
SET EVENT BUFFER SIZE Command
The SET EVENT BUFFER SIZE command will write the
current value of EBUFSIZE[1:0] to the control register.
The EBUFSIZE[1:0] register is only written to the control
register during a SET EVENT BUFFER SIZE command
and ignored at all other times.
When a SET EVENT BUFFER SIZE command is issued
with a new EBUFSIZE[1:0] value, the event data memory
is reinitialized and the event records stored there are lost.
Reinitialization will only occur if the current value of
EBUFSIZE[1:0] is different than the value stored in the
control register.
Reinitialization takes approximately 100µs to complete
and during this period no event records can be generated
and I
issuing a SET EVENT BUFFER SIZE command, it is
recommended to first disable event recording by clearing
the pin event registers A & B, at addresses 0x25 & 0x26
respectively.
Rev. 4.0 (EOL)
July 2010
2
C communication should be suspended.
2
C address register is auto-incrementing,
In order for the EDR to
Before
The following procedure should be used.
In situations where the buffer size is unchanged but its
content and pointers needs to be reinitialized, the host
system should perform the following operations:
Send Reg Address = 0x25
Send Reg Address = 0x20
READDIR, EDRCMD[3:0]
1.
2.
3.
4.
5.
Event Enable A register
Event Enable B register
Sent EBUFSIZE[1:0], 0,
Sent 0x00 to Clear Pin
Sent 0x00 to Clear Pin
EDR Control Register
SET BUFSIZE Command
Send I2C EDR ID
Send I2C EDR ID
+ R/W = 0 (write)
+ R/W = 0 (write)
Clear the Pin Event Enable registers (Step 1 of
previous diagram)
Send the SET EVENT BUFFER SIZE command
with a different EBUFSIZE[1:0] than the current
one (Step 2 of previous diagram)
Wait 100µS for the initialization process to
complete (Step 3 of previous diagram)
Send the SET EVENT BUFFER SIZE command
with the desired EBUFSIZE[1:0] value (Step 2 of
previous diagram, repeat)
Wait 100µS for the initialization process to
complete (Step 3 of previous diagram, repeat)
Wait 100us
I2C Start
I2C Stop
I2C Start
I2C Stop
F
End
IGURE
20. S
ET
B
UFFER
S
IZE COMMAND
Page 17 of 53
Step 1
Step 2
Step 3