Cypress Semiconductor FX2LP Manuel d'utilisateur télécharger pdf (Page 47)

CY7C68013A/CY7C68014A

CY7C68015A/CY7C68016A

Document #: 38-08032 Rev. *K Page 47 of 60

auto mode and it is desired to send two packets back to back:

a full packet (full defined as the number of bytes in the FIFO

meeting the level set in AUTOINLEN register) committed

automatically followed by a short one byte/word packet

committed manually using the PKTEND pin. In this particular

scenario, user must make sure to assert PKTEND at least one

clock cycle after the rising edge that caused the last byte/word

to be clocked into the previous auto committed packet.

Figure 10-12 below shows this scenario. X is the value the

AUTOINLEN register is set to when the IN endpoint is

configured to be in auto mode.

Figure 10-12 shows a scenario where two packets are being

committed. The first packet gets committed automatically

when the number of bytes in the FIFO reaches X (value set in

AUTOINLEN register) and the second one byte/word short

packet being committed manually using PKTEND. Note that

there is at least one IFCLK cycle timing between the assertion

of PKTEND and clocking of the last byte of the previous packet

(causing the packet to be committed automatically). Failing to

adhere to this timing, will result in the FX2 failing to send the

one byte/word short packet.

10.12 Slave FIFO Asynchronous Packet End Strobe

Table 10-14. Slave FIFO Asynchronous Packet End Strobe Parameters

[23]

Parameter Description Min. Max. Unit

PEpwl

PKTEND Pulse Width LOW 50 ns

PWpwh

PKTEND Pulse Width HIGH 50 ns

XFLG

PKTEND to FLAGS Output Propagation Delay 115 ns

IFCLK

SLWR

DATA

Figure 10-12. Slave FIFO Synchronous Write Sequence and Timing Diagram

[20]

IFCLK

>= t

SWR

>= t

WRH

X-2

PKTEND

X-3

FAH

SPE

PEH

FIFOADR

SFD

X-4

FDH

SFA

SFD

X-1

FDH

At least one IFCLK cycle

FLAGS

XFLG

PKTEND

PEpwl

PEpwh

Figure 10-13. Slave FIFO Asynchronous Packet End Strobe Timing Diagram

[20]

1 2 ... 42 43 44 45 46 47 48 49 50 51 52 ... 59 60

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Cypress Semiconductor FX2LP Manuel d'utilisateur Page 47

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