HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 570

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

19.3.16 HcFmNumber Register (HFNR)
HFNR is a 16-bit counter. It indicates the reference of timing between events occurring in the host
controller and host controller driver. The host controller driver uses a 16-bit value specified in this
register and generates a 32-bit frame number without necessity for a frequent access to the
register.
Rev. 1.00, 02/04, page 532 of 804
Bit
31 to 16 —
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Bit Name
FN15
FN14
FN13
FN12
FN11
FN10
FN9
FN8
FN7
FN6
FN5
FN4
FN3
FN2
FN1
FN0
Initial
Value
All 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R/W
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Description
Reserved
These bits are always read as 0. The write value should
always be 0. The operation is not guaranteed if 1 is
written to these bits.
Frame Number
These bits are incremented when the HcFmRemaining
register is reloaded. The count will return to H'0 after
reaching H'FFFF.
When the host controller transits to the USB Operational
state, these bits are automatically incremented. After the
host controller increments the FN15 to FN0 bits and
sends SOF in each frame boundary, the content is written
to HCCA before the host controller reads the first ED in
the frame. After writing to HCCA, the host controller sets
the SF bit in the HcInterruptStatus register.