Renesas M16C FAMILY, Руководство пользователя

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Rev.2.00 Oct 16, 2006 page 174 of 354
REJ09B0340-0200
M30245 Group 2. USB function
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USB endpoint 0 MAXP register
This register indicates the IN/OUT maximum packet size of endpoint 0.
When a GET_DESCRIPTION request is received from the host CPU, write to this register to change
the IN/OUT maximum packet size value of endpoint 0.
Set the packet size value (8, 16 or 32 bytes) specified by control transfer. The default value is 8 bytes.
The configuration of USB endpoint 0 MAXP register is shown in Figure 2.8.33.
●
USB endpoint 0 OUT write count register
This register contains the number of bytes of the current data set in the OUT FIFO. When the USB
function control unit completes the data packet receive from the host CPU, set the value of this regis-
ter. When one buffer data receive completes, read this register and determine the number of bytes to
be read from OUT FIFO. This register value is not decremented even if the data is read from OUT
FIFO.
When CLR_OUT_BUF_RDY bit of the EP0CSR is set to “1”, this register value is cleared to “0”.
The configuration of USB endpoint 0 OUT write count register is shown in Figure 2.8.34.
Figure 2.8.33. USB endpoint 0 MAXP register
Bit Symbol
Bit Name
Function
R W
Must always be “0”
Symbol
EP0MP Address
029A
16
When reset
0008
16
USB Endpoint 0 MAXP register
b7
(b15)
(b8)
b0
EP0MP6-0
b7 b0
Maximum packet size
O O
Reserved
O O
0 0 0 0 0 0 0 0 0
Set maximum packet size
of EP0 IN/OUT
Bit Symbol Bit Name Function R W
O O
Symbol
EP0WC Address
029C
16
When reset
0000
16
USB Endpoint 0 Write Count register
b7
(b15)
(b8)
b0
EP0WC7-0
b7 b0
Receive byte count
O X
Reserved
0 0 0 0 0 0 0 0
Must always be “0”
The number of bytes of the current
data set in EP0 OUT FIFO
Figure 2.8.34. USB endpoint 0 OUT write count register