User`s guide

CY7C63722C
CY7C63723C
CY7C63743C
FOR
FOR
Document #: 38-08022 Rev. *C Page 33 of 49
Mode Column:
The 'Mode' column contains the mnemonic names given to the
modes of the endpoint. The mode of the endpoint is deter-
mined by the four-bit binaries in the 'Encoding' column as
discussed below. The Status IN and Status OUT modes
represent the status IN or OUT stage of the control transfer.
Encoding Column:
The contents of the 'Encoding' column represent the Mode Bits
[3:0] of the Endpoint Mode Registers (Figure 14-2 and
Figure 14-3). The endpoint modes determine how the SIE
responds to different tokens that the host sends to the
endpoints. For example, if the Mode Bits [3:0] of the Endpoint
0 Mode Register (Figure 14-2) are set to '0001', which is NAK
IN/OUT mode as shown in Table 22-1 above, the SIE of the
part will send an ACK handshake in response to SETUP
tokens and NAK any IN or OUT tokens. For more information
on the functionality of the Serial Interface Engine (SIE), see
Section 13.0.
SETUP, IN, and OUT Columns:
Depending on the mode specified in the 'Encoding' column,
the 'SETUP', 'IN', and 'OUT' columns contain the device SIE's
responses when the endpoint receives SETUP, IN, and OUT
tokens respectively.
A 'Check' in the Out column means that upon receiving an
OUT token the SIE checks to see whether the OUT is of zero
length and has a Data Toggle (Data1/0) of 1. If these condi-
tions are true, the SIE responds with an ACK. If any of the
above conditions is not met, the SIE will respond with either a
STALL or Ignore. Table 22-3 gives a detailed analysis of all
possible cases.
A 'TX Count' entry in the IN column means that the SIE will
transmit the number of bytes specified in the Byte Count Bit
[3:0] of the Endpoint Count Register (Figure 14-4) in response
to any IN token.
A 'TX 0 Byte' entry in the IN column means that the SIE will
transmit a zero byte packet in response to any IN sent to the
endpoint. Sending a 0 byte packet is to complete the status
stage of a control transfer.
An 'Ignore' means that the device sends no handshake tokens.
An 'Accept' means that the SIE will respond with an ACK to a
valid SETUP transaction.
Comments Column:
Some Mode Bits are automatically changed by the SIE in
response to many 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 ACKing a
valid status stage OUT token. The firmware needs to update
the mode for the SIE to respond appropriately. See Table 22-1
for more details on what modes will be changed by the SIE.
Any SETUP packet to an enabled endpoint with mode set to
accept SETUPs will be changed by the SIE to 0001 (NAKing).
Any mode set to accept a SETUP will send an ACK handshake
to a valid SETUP token.
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 SetCon-
figuration request.
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.
Table 22-2. Decode table for Table 22-3: “Details of Modes for Differing Traffic Conditions”
Endpoint Mode
Encoding
Properties of incoming
packet
Changes to the internal register made by the SIE as a result of
the incoming token
Interrupt?
End Point
Mode
3 2 1 0 Token count buffer dval DTOG DVAL COUNT
Setup In Out ACK 3 2 1 0 Response Int
Bit[3:0], Figure 14-4 SIE’s Response
Data Valid (Bit 6, Figure 14-4) Endpoint Mode changed
by the SIE.
Data 0/1 (Bit 7, Figure 14-4)
Received Token
(SETUP, IN,OUT)
The validity of the received data Acknowledge transaction completed
(Bit4,Figure 14-2/3)
The quality status of the DMA buffer PID Status Bits
(Bit[7:5], Figure 14-2)
The number of received bytes
Legend:
UC: unchanged TX: transmit TX0: transmit 0-length packet
x: don’t care RX: receive
available for Control endpoint only