Universal Serial Bus Controller User's Guide

4.53 Frame Number Register (FRAME)
4.54 Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
www.ti.com Registers
The Frame Number Register (FRAME) is shown in Figure 68 and described in Table 69 .
Figure 68. Frame Number Register (FRAME)
15 11 10 0
Reserved FRAMENUMBER
R-0 R-0
LEGEND: R = Read only; - n = value after reset
Table 69. Frame Number Register (FRAME) Field Descriptions
Bit Field Value Description
15-11 Reserved 0 Reserved
10-0 FRAMENUMBER 0-7FFh Last received frame number
The Index Register for Selecting the Endpoint Status and Control Registers (INDEX) is shown in Figure 69
and described in Table 70 .
Figure 69. Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
7 4 3 0
Reserved EPSEL
R-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; - n = value after reset
Table 70. Index Register for Selecting the Endpoint Status and Control Registers (INDEX)
Field Descriptions
Bit Field Value Description
7-4 Reserved 0 Reserved
3-0 EPSEL 0-Fh Each transmit endpoint and each receive endpoint have their own set of control/status registers. EPSEL
determines which endpoint control/status registers are accessed.
Before accessing an endpoint's control/status registers, the endpoint number should be written to the
Index register to ensure that the correct control/status registers appear in the memory map.
SPRUGH3 – November 2008 Universal Serial Bus (USB) Controller 117
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