USB Device Controller
1587
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
29.3.1.20 Receive DMA Control Register n (RXDMAn)
This read/write register monitors incoming OUT transactions during DMA transfer on channel n (n=0,1,2).
Figure 29-47. Receive DMA Control Register n (RXDMAn)
[address = FCF78A30h to FCF78A34h]
15
14
8
RXn_STOP
Reserved
R/W-0
R-0
7
0
RXn_TC
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value at reset
Table 29-51. Receive DMA Control Register n (RXDMAn) Field Descriptions
Bit
Field
Value
Description
15
RXn_STOP
0-1
Receive DMA channel n transfer stop. When this bit is set, an RXn_EOT interrupt is asserted to the
USB device controller after n OUT transactions where n is the encoded binary value + 1
programmed into RXDMAn.RXn_TC field. This register is used when no smaller than buffer size
packet is received at an end-of-transfer (EOT), and the USB device controller expects a given
amount of data for the transfer.
Note: At end of transfer, the DMA channel is disabled and all OUT transactions received to the
assigned endpoint are sent NAK by the core. The USB device controller must set
CTRL.SET_FIFO_EN for the endpoint to reenable the channel.
Values after system reset or USB reset are low.
14-8
Reserved
0
Reserved
7-0
RXn_TC
0-FFh
Receive DMA channel n transactions count. The USB device controller can ask for an interrupt
each n OUT transactions where n is the encoded binary value + 1 programmed into
RXDMAn.RXn_TC field. This register must be programmed to the desired transaction watermark
limit prior to enabling the DMA transfer for the receive DMA channel n.
Note: A reached watermark does not disable an active DMA transfer if RXDMAn.RXn_STOP was
not set. If RXDMAn.RXn_STOP was set for the transfer both RXn_CNT and RXn_EOT interrupts
are asserted. A read to that register returns the number of transactions remaining before the
IRQ_SRC.RXn_CNT interrupt flag is asserted. This read mode is only provided for software debug
purposes.
Values after system reset or USB reset are low (all 8 bits).