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Spinpoint M8U-Internal Product Manual REV 3.4
54
INSTALLATION
• Message Pipes have a defined USB format. They are host controlled, which are initiated by a request
sent from the host. Data is then transferred in the desired direction, dictated by the request. Therefore
message pipes allow data to flow in both directions but will only support control transfers.
6.3.5 Transfer/Endpoint Types
The Universal Serial Bus specification defines four transfer/endpoint types,
• Control Transfers
• Interrupt Transfers
• Isochronous Transfers
• Bulk Transfers
■ Control Transfer
- Packet Length: 8bytes (Low), 8, 16, 32 or 64bytes (High), 64bytes (Full)
- Stage
- SetUp Stage: SETUP->DATA 0->ACK Packet
- Optional Data Stage: IN (Data transmit), OUT (Control need) Packet
- Status Stage: IN/OUT packet for reports the status of the overall
- Command/Status Operation.
ex) Device Setup data transfer
■ Interrupt Transfer
- Guaranteed Latency
- Stream Pipe - Unidirectional
- Error detection and next period retry
- Maximum data payload size: 8bytes (Low), 64bytes (Full), 1024bytes (High)
ex) Mouse, JoyStick, Keyboard
■ Isochronous Transfer
- Guaranteed access to USB bandwidth
- Bounded latency
- Stream Pipe - Unidirectional
- Error detection via CRC, but no retry or guarantee of delivery
- Full & high speed modes only
- No data toggling
- Maximum data payload size: 1023bytes (Full), 1024bytes (High)
ex) Audio, Telephone
■ Bulk Transfer
- Used to transfer large bursty data
- Error detection via CRC, with guarantee of delivery
- No guarantee of bandwidth or minimum latency
- Stream Pipe - Unidirectional
- Full & high speed modes only
- Maximum bulk packet size - 8, 16, 32 or 64bytes (Full), up to 512bytes (High)
- Large Data Operation ex)
Print, Scanner, Still Camera
Spinpoint M8U USB Storage Device use Control Transfer to do command and status operation, and Bulk
Transfer to read or write operation.