Datasheet

PCKSIZE.MULTI_PACKET_SIZE. This value must be a multiple of PCKSIZE.SIZE, otherwise excess
data may be written to SRAM locations used by other parts of the application.
EPSTATUS.DTGLOUT management for non-isochronous packets and EPINTFLAG.BK1RDY/BK0RDY
management are as for normal operation.
If a maximum payload size packet is received, PCKSIZE.BYTE_COUNT will be incremented by
PCKSIZE.SIZE after the transaction has completed, and EPSTATUS.DTGLOUT will be toggled if the
endpoint is not isochronous. If the updated PCKSIZE.BYTE_COUNT is equal to
PCKSIZE.MULTI_PACKET_SIZE (i.e. the last transaction), EPSTATUS.BK1RDY/BK0RDY, and
EPINTFLAG.TRCPT0/TRCPT1 will be set.
32.6.2.9 Management of IN Transactions
Figure 32-5. IN Transfer: Data Packet USB Device to Host After Request from Host
Internal RAM
USB Module
USB Endpoints
Descriptor Table
USB Buffers
ENDPOINT 1 DATA
ENDPOINT 2 DATA
ENDPOINT 3 DATA
D
A
T
A
0
D
A
T
A
0
D
A
T
A
0
D
A
T
A
1
D
A
T
A
0
D
A
T
A
1
D
A
T
A
0
D
A
T
A
1
D
A
T
A
0
D
A
T
A
1
D
A
T
A
0
EPT 2 EPT 3 EPT 1
DP
DM
HOST
CPU
I
N
T
O
K
E
N
I
N
T
O
K
E
N
I
N
T
O
K
E
N
EPT 2 EPT 3 EPT 1
time
USB I/O Registers
Memory Map
I/O Register
DESCADD
When an IN token is detected, and if the device address of the token packet does not match
DADD.DADD, the packet is discarded and the USB module returns to idle and waits for the next token
packet.
When the address matches, the USB module checks if the endpoint received is enabled in the EPCFG of
the addressed endpoint and if not, the packet is discarded and the USB module returns to idle and waits
for the next token packet.
When the endpoint is enabled, the USB module then checks on the EPCFG of the addressed input
endpoint. If the EPCFG.EPTYPE1 is not set to IN, the USB module returns to idle and waits for the next
token packet.
SAM D21 Family
USB – Universal Serial Bus
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 800