9397 750 XXXXX
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
214
Philips Semiconductors
UM10139
Volume 1
Chapter 14: USB Device Controller
14.8.11 USB DMA Request Status register (USBDMARSt - 0xE009 0050)
This register is set by the hardware whenever a packet (OUT) or token (IN) is received on
a realized endpoint. It serves as a flag for DMA engine to start the data transfer if the DMA
is enabled for this particular endpoint. Each endpoint has one reserved bit in this register.
Hardware sets this bit when a realized endpoint needs to be serviced through DMA.
Software can read the register content. DMA cannot be enabled for control endpoints
(EP0 and EP1). For easy readability the control endpoint is shown in the register contents.
The USBDMARSt is a read only register.
[1]
DMA can not be enabled for this endpoint and the corresponding bit in the USBDMARSt must be 0.
14.8.12 USB DMA Request Clear register (USBDMARClr - 0xE009 0054)
Writing 1 into the register will clear the corresponding interrupt from the DMA Request
Status register. Writing 0 will not have any effect. Also, after a packet transfer, the
hardware clears the particular bit in DMA Request Status register. The USBDMARClr is a
write only register.
The USBDMARClr bit allocation is identical to the USBDMARSt register (
Table 205: USB Command Data register (USBCmdData - address 0xE009 0014) bit
description
Bit
Symbol
Description
Reset value
7:0
CommandData Command Data.
0x00
31:8
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
Table 206: USB DMA Request Status register (USBDMARSt - address 0xE009 0050) bit allocation
Reset value: 0x0000 0000
Bit
31
30
29
28
27
26
25
24
Symbol
EP31
EP30
EP29
EP28
EP27
EP26
EP25
EP24
Bit
23
22
21
20
19
18
17
16
Symbol
EP23
EP22
EP21
EP20
EP19
EP18
EP17
EP16
Bit
15
14
13
12
11
10
9
8
Symbol
EP15
EP14
EP13
EP12
EP11
EP10
EP9
EP8
Bit
7
6
5
4
3
2
1
0
Symbol
EP7
EP6
EP5
EP4
EP3
EP2
EP1
EP0
Table 207: USB DMA Request Status register (USBDMARSt - address 0xE009 0050) bit description
Bit
Symbol
Value
Description
Reset value
0
EP0
0
Control endpoint OUT (DMA cannot be enabled for this endpoint and EP0
bit must be 0).
0
1
EP1
0
Control endpoint IN (DMA cannot be enabled for this endpoint and EP1 bit
must be 0).
0
31:2
EPxx
Endpoint xx (2
≤
xx
≤
31) DMA request.
0
0
DMA not requested by endpoint xx.
1
DMA requested by endpoint xx.