at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 404

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Figure 167. Data IN Transfer for Ping-pong Endpoint
404
TXPKTRDY Flag
(USB_MCSRx)
FIFO (DPR)
Bank 0
FIFO (DPR)
USB Bus
Packets
TXCOMP Flag
(USB_CSRx)
Bank 1
AT91RM3400
Written by
Microcontroller
Microcontroller
Load Data IN Bank 0
Set by Firmware,
Data Payload Written in FIFO Bank 0
Data IN
PID
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 is too long, some Data IN packets may be NACKed,
reducing the bandwidth.
Microcontroller Load Data IN Bank 1
USB Device Send Bank 0
Written by
Microcontroller
Read by USB Device
Data IN
Cleared by USB Device,
Data Payload Fully Transmitted
Set by USB
Device
ACK
PID
Interrupt Cleared by Firmware
Data IN
PID
Interrupt Pending
Microcontroller Load Data IN Bank 0
USB Device Send Bank 1
Written by
Microcontroller
Set by Firmware,
Data Payload Written in FIFO Bank 1
Read by USB Device
Data IN
Set by USB Device
1790A–ATARM–11/03
ACK
PID