ORSPI4 datasheet(58/263 Pages) LATTICE

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Lattice Semiconductor

ORCA ORSPI4 Data Sheet

• TX_CAL_M_MAIN (address 30921 in SPIA and 30A21 in SPIB) is set to the number of times the calendar

sequence needs to be repeated between framing patterns.

• The shadow calendar can be programmed in the same identical fashion as the main calendar using the steps

described above.

To enable hitless switching between main and shadow calendar memories, the TX_CAL_SW_EN bit (address

30916 in SPIA and 30A16 in SPIB) should be set to ‘1’. This will cause the transmit status logic to detect the calen-

dar select word after the framing pattern. A “01” detected on the calendar select word selects the main calendar. A

“10” on the calendar select word selects the shadow calendar. It is important to enable this feature in the receive

device on the other end of the SPI4 link. If the receive device is a Lattice ORSPI4 device, this is done by setting

RX_CAL_SW_EN bit (address 30916 in SPIA and 30A16 in SPIB) to ‘1’. This will cause the far-end receive status

logic to insert the calendar select word after the framing pattern.

Table 11. Transmit Calendar Memory Contents

MIN_BURST_MODE

The number of transmitted data bytes in a given port’s SPI-4 data segment can be programmed by setting the

BURST_VAL for a given port in the Port Descriptor Memory. In general, setting a port’s BURST_VAL will result in

transmitted data segments of length (16 * BURST_VAL) bytes. However, data segments shorter than (16 *

BURST_VAL) bytes will occur about 15% of the time. There are three reasons for shorter data segments:

1. End-of-packet (EOP) causes segment to terminate

2. Insufﬁcient data is written into a port’s transmit FIFO to support a full data burst.

3. ORSPI4 core logic causes occasional short segments.

Reason 1 will always naturally occur with any SPI4 link and so can never be completely eliminated. However, the

following steps which take advantage of the MIN_BURST_MODE will eliminate short data segments caused by

reasons 2 and 3:

1. Set MIN_BURST_MODE (address 30916, bit 3 for SPIA and 30A16, bit 3 for SPIB) to 1.

TX Calendar Memory

Address

TX Calendar Memory

Contents (Port ID)

Port Number

0x00

0x01

0x02

0x03

0x04

0x00

0x05

0x01

0x06

0x02

0x07

0x04

0x08

0x00

0x09

0x01

0x0a

0x02

0x0b

0x05

0x0c

0x00

0x0d

0x01

0x0e

0x02

0x0f

0x06

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