One Stop Systems Multi Port E1, Быстрое руководство

Страница: 12 / 15

One Stop Systems, Inc. OSS-wanPCI-CxT1E1 User Manual
Rev. A 12
In-System Programmable Logic Device (iSPLD)
The In-System Programmable Logic Device (iSPLD) contains all of the necessary logic required by the CN8474A to communicate
with its peripheral components. The iSPLD serves two purposes
:
1. As a general logic device, supplying correct signal timing and address decoding for chip selects to the COMETs and
EEPROM.
2. To provide registers to control the crystal routing and BRCLK routes to and from the COMETs and MUSYCC.
The iSPLD is an Altera EPM3256AE and serves the following logic functions:
• T1/E1/J1 clock routing to all COMETs
• COMET interrupts
• Serial EEPROM control
• COMET control
• LED control
• Master clock connections
• Reset functions
iSPLD registers, base address (EAD) = 0xD0000
iSPLD Control Functions
Write/read operations executed by the CN8474A via its EBus are translated to the appropriate timing for the PMC4351. The iSPLD
decodes the address and generates the chip-select levels for each of the COMETs
Master Clock Select Register
Any or all of the COMETs can provide the clock for data synchronization. The host, via the MCSR, decides which COMET provides
the clock. At reset, each COMET provides the clock for its port and must be configured as the master. In modes other than default
or reset, one port is assigned the master with the iSPLD routing this clock to the remaining COMETs and MUSYCC.
The MCSR in the iSPLD can be written to and read by the PCI host. Immediately after powerup or host reset this register is
initialized to all zeros. By default, COMET 1 serves to provide the master clock. The host may then select the clocking needs via the
MCSR. See Master Clock Registers Table on next page for information about the MCSR and clocking information.
The MCSR in the CPLD is a read/write register combined with the Board ID Register (BIDR), a read-only register. The power-up
default value of this register is 10 Hex
.
BIDR Register – Address = 0xD0000 MCSR Register – Address = 0xD0000
Read Only Read/Write
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 1 MCSR3 MCSR2 MCSR1 MCSR0
Address offset Register type Function
0x0 Write/read MCSR
0x4 Write/read MCLK register
0x8 Write/read LED register
0xC Read only Interrupt register