XP2 Datasheet, PDF (30/92 Pages) Lattice Semiconductor – LatticeXP2 Family Data Sheet

Lattice Semiconductor
Architecture
LatticeXP2 Family Data Sheet
Table 2-11. PIO Signal List
Name
Type
Description
CE
Control from the core
Clock enables for input and output block flip-flops
CLK
Control from the core
System clocks for input and output blocks
ECLK1, ECLK2 Control from the core
Fast edge clocks
LSR
Control from the core
Local Set/Reset
GSRN
Control from routing
Global Set/Reset (active low)
INCK²
Input to the core
Input to Primary Clock Network or PLL reference inputs
DQS
Input to PIO
DQS signal from logic (routing) to PIO
INDD
Input to the core
Unregistered data input to core
INFF
Input to the core
Registered input on positive edge of the clock (CLK0)
IPOS0, IPOS1
Input to the core
Double data rate registered inputs to the core
QPOS0¹, QPOS1¹ Input to the core
Gearbox pipelined inputs to the core
QNEG0¹, QNEG1¹ Input to the core
Gearbox pipelined inputs to the core
OPOS0, ONEG0,
OPOS2, ONEG2
Output data from the core
Output signals from the core for SDR and DDR operation
OPOS1 ONEG1 Tristate control from the core Signals to Tristate Register block for DDR operation
DEL[3:0]
Control from the core
Dynamic input delay control bits
TD
Tristate control from the core Tristate signal from the core used in SDR operation
DDRCLKPOL
Control from clock polarity bus Controls the polarity of the clock (CLK0) that feed the DDR input block
DQSXFER
Control from core
Controls signal to the Output block
1. Signals available on left/right/bottom only.
2. Selected I/O.
PIO
The PIO contains four blocks: an input register block, output register block, tristate register block and a control logic
block. These blocks contain registers for operating in a variety of modes along with necessary clock and selection
logic.
Input Register Block
The input register blocks for PIOs contain delay elements and registers that can be used to condition high-speed
interface signals, such as DDR memory interfaces and source synchronous interfaces, before they are passed to
the device core. Figure 2-26 shows the diagram of the input register block.
Input signals are fed from the sysIO buffer to the input register block (as signal DI). If desired, the input signal can
bypass the register and delay elements and be used directly as a combinatorial signal (INDD), a clock (INCK) and,
in selected blocks, the input to the DQS delay block. If an input delay is desired, designers can select either a fixed
delay or a dynamic delay DEL[3:0]. The delay, if selected, reduces input register hold time requirements when
using a global clock.
The input block allows three modes of operation. In the Single Data Rate (SDR) mode, the data is registered, by
one of the registers in the SDR Sync register block, with the system clock. In DDR mode two registers are used to
sample the data on the positive and negative edges of the DQS signal which creates two data streams, D0 and D2.
D0 and D2 are synchronized with the system clock before entering the core. Further information on this topic can
be found in the DDR Memory Support section of this data sheet.
By combining input blocks of the complementary PIOs and sharing registers from output blocks, a gearbox function
can be implemented, that takes a double data rate signal applied to PIOA and converts it as four data streams,
IPOS0A, IPOS1A, IPOS0B and IPOS1B. Figure 2-26 shows the diagram using this gearbox function. For more
information on this topic, please see TN1138, LatticeXP2 High Speed I/O Interface.
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