CY7C64013C CY7C64113CDocument #: 38-08001 Rev. *B Page 40 of 51
An “Accept” in any of the columns means that the device will respond with an ACK to a valid SETUP transaction tot he host.
Comments
Some Mode Bits are automatically changed by the SIE in response to certain USB transactions. For example, if the Mode Bits
[3:0] are set to '1111' which is ACK IN-Status OUT mode as shown in table 22-1, the SIE will change the endpoint Mode Bits [3:0]
to NAK IN-Status OUT mode (1110) after ACK’ing a valid status stage OUT token. The firmware needs to update the mode for
the SIE to respond appropriately. See Table 18-1 for more details on what modes will be changed by the SIE. A disabled endpoint
will remain disabled until changed by firmware, and all endpoints reset to the disabled mode (0000). Firmware normally enables
the endpoint mode after a SetConfiguration request.
Any SETUP packet to an enabled endpoint with mode set to accept SETUPs will be changed by the SIE to 0001 (NAKing INs
and OUTs). Any mode set to accept a SETUP will send an ACK handshake to a valid SETUP token.
The control endpoint has three status bits for identifying the token type received (SETUP, IN, or OUT), but the endpoint must be
placed in the correct mode to function as such. Non-Control endpoints should not be placed into modes that accept SETUPs.
Note that most modes that control transactions involving an ending ACK, are changed by the SIE to a corresponding mode which
NAKs subsequent packets following the ACK. Exceptions are modes 1010 and 1110.
Note: The SIE offers an “Ack out–Status in” mode and not an “Ack out–Nak in” mode. Therefore, if following the status stage of
a Control Write transfer a USB host were to immediately start the next transfer, the new Setup packet could override the data
payload of the data stage of the previous Control Write.
The response of the SIE can be summarized as follows:
1.The SIE will only respond to valid transactio ns, and will ignore non-valid ones.
2.The SIE will genera te an interrupt when a valid transaction is completed or when the FIFO is corrupted. FIFO corruption occurs
during an OUT or SETUP transaction to a valid internal address, that ends with a non-valid CRC.
3.An incoming Data packet is valid if the count is < Endpoint Size + 2 (includes CRC) and passes all error checking;
4.An IN will be ignored by an OUT configured endpoint and visa versa.
5.The IN and OUT PID status is updated at the end of a transaction.
6.The SETUP PID status is updated at the beginning of the Data packet phase.
7.The entire Endpoint 0 mode register and the Coun t register are locked to CPU writes at the end of any transaction to that
endpoint in which an ACK is transferred. These registers are only unlocked by a CPU read of the register, which should be
done by the firmware only after the transaction is complete. This represents about a 1- µs window in which the CPU is locked
from register writes to these USB registers. Normally the firmware should perform a register read at the beginning of the
Endpoint ISRs to unlock and get the mode register information. The interlock on the Mode and Count registers ensures that
Properties of
Incoming Packets
Changes to the Internal Register made by the SIE on receiving an incoming packet
from the host Interrupt
3 2 1 0 Token count buffer dval DTOG DVAL COUNT Setup In Out ACK 3 2 1 0 Response Int
Byte Count (bits 0..5, Figure 17-4)
SIE’s Response
to the Host
Endpoint Mode
encoding
Data Valid (bit 6, Figure 17-4)
Received Token
(SETUP/IN/OUT)
Data0/1 (bit7 Figure 17-4)
PID Status Bits
(Bit[7..5], Figure 17-2)
Endpoint Mode bits
Changed by the SIE
The validity of the received data
The quality status of the DMA buffer
The number of received bytes Acknowledge phase completed
Legend: TX : transmit UC : unchanged
RX : receive TX0 :Transmit 0 length packet
available for Control endpoint only
x: don’t care
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