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30.5.4
Data Packet
This chapter describes the Data Packet processing procedure.
■ Data Packet
If a data packet is transmitted after a packet token has been sent, a toggle data will be transmitted
based on the HTOKEN:TGGL bit, as well as the buffer data, the CRC16 data, and EOP is sent. In
case a data packet transmission, the transmitted HTOKEN:TGGL bit and the received toggle data
are compared, and, if they match, the received data is written to the endpoint corresonding to
EP1C:DIR bit value, and the CRC16 is checked for an error later on.
After sending a token packet, the data packet is executed in the following procedure:
●
At Transmission
• Sync is sent automatically.
•
D ATA0 is transmitted when the HTOKEN:TGGL bit is "0" and DATA1 is transmitted when the
HTOKEN:TGGL bit is "1".
• When the EP1C:DIR is set to "1", the buffer for endpoint 1 is selected, otherwise endpoint 2
buffer is selected.
• The CRC16-bit is sent.
• The EOP 2-bit is sent.
• The J State 1-bit is sent.
●
At Reception
• Sync is received
• The toggle data is received and compared with the HTOKEN:TGGL bit.
• If they match, depending of EP1C:DIR bit the endpoint buffer is selected and the received data
is written into it.
• When the EOF is received, the CRC16 bit is checked.
• The inversion data must be set, respectively, in the EP1C:DIR bits (resp EP2C) when the
HCNT0:HOST bit is "1". For example, when the EP1C:DIR bit is "0", the EP2C:DIR bit is set to
"1".
CHAPTER 30 USB Mini-host
801
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