Usb Frame Number Registers; Usb Iso Control Register - Renesas M16C Series User Manual

M30240 Group

3.2.2.7 USB Frame Number Registers

These two registers hold the frame number (11 bits) received from the host CPU. They are read only.
Figure 3.13 shows the structures of the USB frame number registers.
USB Frame Number Low Register
b7
USB Frame Number High Register
b7
O O O O O
Figure 3.13: USB Frame Number Registers (USBSOFL, USBSOFLH)

3.2.2.8 USB ISO Control Register

The USB ISO Control Register contains two bits: ISO_UPD and AUTO_FL. These bits are used to
control endpoints 1-4 during isochronous transfers.
• AUTO_FLUSH Bit
When the ISO bit (INxCSR3) ="1", the ISO_UPDATE bit ="1"and the AUTO_FLUSH ="1", the USB
function control unit automatically flushes the oldest data packet within the FIFO if the IN_PKT_RDY
(INxCSR0) ="1" at time of an SOF packet detection.
• ISO_UPDATE Bit
In the case that the ISO_UPDATE bit ="1", the IN FIFO data is transmitted when the USB function
control unit receives the next IN token from the host CPU.
When the ISO_UPDATE bit ="1" and the ISO bit (INxCSR3) ="1", the USB function control unit does
not conduct transmission even if an IN token is received from the host CPU; it delays the transmission
until the next SOF is detected.
Figure 3.14 shows the structure of the ISO Control Register.
USB ISO Control Register
b7 b6 b5 b4
O O O O O O
Figure 3.14: USB ISO Control Register (USBISOC)
Rev.1.00 Sep 24, 2003 Page 300 of 360
b6 b5 b4 b3 b2 b1 b0
Symbol
USBSOFL
Bit Symbol
FN0 to FN7
b6 b5 b4 b3 b2 b1 b0
Symbol
USBSOFH
Bit Symbol
FN8
FN9
FN10
Reserved
b3 b2 b1 b0
Symbol
USBISOC
Bit Symbol
Reserved
AUTO_FL AUTO FLUSH Bit
ISO_UPD
Address When reset
0306
16
Bit Name Function
Lower 8 bits of the 11-bit
USB Frame number bit frame number issued with
and SOF token
Address When reset
0307
16
Bit Name Function
Upper 3 bits of the 11-bit
frame number issued with
USB Frame number bit
an SOF token
Must always be set to "0"
Address
0308
16
Bit Name
Must always be set to "0"
0 : Hardware auto FIFO flush disabled
1 : Hardware auto FIFO flush enabled
0 : ISO_UPDATE disabled
ISO-UPDATE Bit
1 : ISO_UPDATE enabled
Universal Serial Bus
00
16
R W
O X
00
16
R W
O X
O O
When reset
00
16
Function R W
O O
O O
O O