Packet Size
Name:
PCKSIZE
Offset:
0x04 & 0x14
Reset:
0xxxxxxxxx
Access:
NA
Bit3130292827262524
AUTO_ZLPSIZE[2:0]MULTI_PACKET_SIZE[13:10]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000
Bit2322212019181716
MULTI_PACKET_SIZE[9:2]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000
Bit15141312111098
MULTI_PACKET_SIZE[1:0]BYTE_COUNT[13:8]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000
Bit76543210
BYTE_COUNT[7:0]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Reset00000000

Bit 31 – AUTO_ZLP: Automatic Zero Length Packet

Automatic Zero Length Packet

This bit defines the automatic Zero Length Packet mode of the endpoint.

When enabled, the USB module will manage the ZLP handshake by hardware. This bit is for IN endpoints only. When disabled the handshake should be managed by firmware.

ValueDescription
0 Automatic Zero Length Packet is disabled.
1 Automatic Zero Length Packet is enabled.

Bits 30:28 – SIZE[2:0]: Endpoint size

Endpoint size

These bits contains the maximum packet size of the endpoint.

Value Description
0x0 8 Byte
0x1 16 Byte
0x2 32 Byte
0x3 64 Byte
0x4 128 Byte(1)
0x5 256 Byte(1)
0x6 512 Byte(1)
0x7 1023 Byte(1)
(1) for Isochronous endpoints only.

Bits 27:14 – MULTI_PACKET_SIZE[13:0]: Multiple Packet Size

Multiple Packet Size

These bits define the 14-bit value that is used for multi-packet transfers.

For IN endpoints, MULTI_PACKET_SIZE holds the total number of bytes sent. MULTI_PACKET_SIZE should be written to zero when setting up a new transfer.

For OUT endpoints, MULTI_PACKET_SIZE holds the total data size for the complete transfer. This value must be a multiple of the maximum packet size.

Bits 13:0 – BYTE_COUNT[13:0]: Byte Count

Byte Count

These bits define the 14-bit value that is used for the byte count.

For IN endpoints, BYTE_COUNT holds the number of bytes to be sent in the next IN transaction.

For OUT endpoint or SETUP endpoints, BYTE_COUNT holds the number of bytes received upon the last OUT or SETUP transaction.