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CHAPTER 11 USB FUNCTION
11.4 Operation Explanation of USB Function
• To automatically execute STALL response with hardware.
The procedures to execute STAL response with hardware are shown in Figure 11.4-11. When STALL
response is set with Set Feature command, the hardware would automatically set the internal condition
bit of the relevant endpoint and gives the STALL response regardless of the STAL bit. Once the internal
condition bit is set, the internal condition bit has been held until Clear Feature command is issued from
the host to clear the internal condition bit regardless of STAL bit. After the relevant bit is cleared with
Clear Feature command, STAL bit is referenced. Therefore, to clear STAL response, be sure to clear the
internal condition bit with Clear Feature command.
Figure 11.4-11 Case where STALL response is executed with hardware automatically
Host or hub
Set Feature
command to EP0
(EPn is specified.)
Transaction
to EPn
Clear Feature
command to EP0
(EPn is specified.)
234
Setup token
Data (at OUT)
ACK handshake
IN/OUT token
Data (at OUT)
STALL handshake
Setup token
Data
ACK handshake
FUJITSU MICROELECTRONICS LIMITED
Function
EPn (End Point n)
of Function Macro
Internal
STAL bit
Condition bit
0
0
When EPn is specified with
Set Feature command, the
internal condition bit is set
to "1".
Internal
STAL bit
Condition bit
1
0
When the internal condition
bit is "1", STALL response to
a transaction continues.
Although STAL bit is "0", it
does not affect the internal
condition bit.
Internal
STAL bit
Condition bit
0
0
When EPn is specified with
Set Feature command, the
internal condition bit is
cleared to "0".
MB90335 Series
Software
CM44-10137-6E
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