13-5
Lattice Semiconductor
LatticeXP sysCONFIG Usage Guide
Table 13-4. Maximum Configuration Bits
Table 13-5. SDM Pin Usage
Table 13-6. Pins Used for Memory Access
Programming Sequence
There are three types of programming, SRAM, Flash Direct, and Flash Background. This section goes through the
process for each showing how the dedicated pins are used.
SRAM: When not using SDM (Self Download Mode, on-chip Flash) to program SRAM the sequence begins when
the internal power-on reset (POR) is released or the PROGRAMN pin is driven low (see
Figure 13-2). The Lattic-
eXP then drives INITN low, tri-states the I/Os, and initializes the internal SRAM and control logic. When this is com-
Density
Bitstream Size (Mb)
LFXP3
1
LFXP6
1.6
LFXP10
2.8
LFXP15
4
LFXP20
4.9
Configuration Mode
SDM (Self Download Mode)
CFG[1:0]
[1, 1]
Flash Programming Mode
Direct
Background
Direct
Background
Port
sysCONFIG
ispJTAG
1
Pins
CCLK, CSN, CS1N, WRITEN, D[0:7]
TAP
User I/O States
Tristate
User
BSCAN
User
PROGRAMN
Keep at High
Keep At High
2
BUSY
Status
Not Used
INITN
Pass/Fail
Not Used
3
DONE
Done
Not Used
Keep at High
4
PERSISTENT Bit
Don’t Care
ON
Don’t Care
1. ispJTAG can be used to program the Flash regardless of the state of the CFG pins, however only if the device is in SDM can Flash be used
to configure SRAM
2. The state of the PROGRAMN pin is ignored by the device during JTAG Flash programming but the pin should be held high as a low will
inhibit Flash to SRAM data transfer.
3. The state of the INITN pin is ignored by the device during JTAG Flash programming but the pin should be allowed to float high using the
internal pull-up.
4. The state of the DONE pin is ignored by the device during JTAG Flash programming but the pin should be allowed to float high using the
internal pull-up as a low can keep the device from waking up.
CFG Pins
CFG Mode
On-Chip Flash
SRAM
1
0
Write or Read
2
Write From
Readback
2, 3
X
1
X
1
JTAG
TAP
1
SDM
sysCONFIG
On-Chip Flash
sysCONFIG
1
0
Slave Parallel
N/A
4
sysCONFIG
0
1
Master Serial
N/A
4
sysCONFIG
N/A
5
0
Slave Serial
N/A
4
sysCONFIG
N/A
5
1. The ispJTAG port is always available independent of the CFG setting.
2. Readback can only be disabled by programming the security bit.
3. Set the PERSISTENT bit to ON to retain the sysCONFIG port for background readback.
4. Flash access is not allowed in this mode.
5. SRAM readback is not allowed in this mode.