Datasheet

SAM9261 [DATASHEET]
Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16
594
Figure 36-8. Data IN Transfer for Ping-pong Endpoint
Warning: There is software critical path due to the fact that once the second bank is filled, the driver has to wait for
TX_COMP to set TX_PKTRDY. If the delay between receiving TX_COMP is set and TX_PKTRDY is set too long,
some Data IN packets may be NACKed, reducing the bandwidth.
Warning: TX_COMP must be cleared after TX_PKTRDY has been set.
Data INData IN
Read by USB Device
Read by USB Device
Bank 1
Bank 0
FIFO (DPR)
TXCOMP Flag
(UDP_CSRx)
Interrupt Cleared by Firmware
Set by USB
Device
TXPKTRDY Flag
(UDP_MCSRx)
ACK
PID
Data IN
PID
ACK
PID
Set by Firmware,
Data Payload Written in FIFO Bank 1
Cleared by USB Device,
Data Payload Fully Transmitted
Data IN
PID
USB Bus
Packets
Set by USB Device
Set by Firmware,
Data Payload Written in FIFO Bank 0
Written by
FIFO (DPR)
Microcontroller
Written by
Microcontroller
Written by
Microcontroller
Microcontroller
Load Data IN Bank 0
Microcontroller Load Data IN Bank 1
USB Device Send Bank 0
Microcontroller Load Data IN Bank 0
USB Device Send Bank 1
Interrupt Pending