M67206F
Table 1.
Reset and Retransmit
Single Device Configuration/Width Expansion Mode
Inputs
Mode
Reset
Retransmit
Read/Write
Note:
RS
0
1
1
Internal Status
XI
0
0
0
Outputs
EF
0
X
X
RT
X
0
1
Read Pointer
Location Zero
Location Zero
Increment
(1)
Write Pointer
Location Zero
Unchanged
Increment
(1)
FF
1
X
X
HF
1
X
X
1. Pointer will increment if flag is high.
Table 2.
Reset and First Load Truth Table
Depth Expansion/Compound Expansion Mode
Inputs
Mode
Reset First Device
Reset All Other
Devices
Read/Write
Note:
RS
0
Internal Status
XI
(1)
Outputs
EF
0
FL
0
Read Pointer
Location Zero
Location Zero
X
Write Pointer
Location Zero
Location Zero
X
FF
1
0
1
(1)
0
1
1
X
(1)
X
X
1. XI is connected to XO of previous device.
See Figure 4.
Depth Expansion (Daisy
Chain) Mode
The M67206F can be easily adapted for applications which require more than 16384
words. Figure 4 demonstrates Depth Expansion using three M67206Fs. Any depth can
be achieved by adding an additional M67206F.
The M67206F operates in the Depth Expansion configuration if the following conditions
are met:
1. The first device must be designated by connecting the First Load (FL) control
input to ground.
2. All other devices must have FL in the high state.
3. The Expansion Out (XO) pin of each device must be connected to the Expansion In
(XI) pin of the next device. See Figure 4
4. External logic is needed to generate a composite Full Flag (FF) and Empty Flag
(EF). This requires that all EF’s and all FFs be ORed (i.e. all must be set to generate the
correct composite FF or EF). See Figure 4.
5. The Retransmit (RT) function and Half-Full Flag (HF) are not available in the Depth
Expansion Mode.
Compound Expansion
Module
It is quite simple to apply the two expansion techniques described above together to cre-
ate large FIFO arrays (see Figure 5).
7
4143F–AERO–06/02
ATMEL [ ATMEL CORPORATION ]
