HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 920

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 25
25.8.3
When a stall setting is made with the Set Feature command, or in the event of a USB specification
violation, the USB function controller automatically sets the internal status bit for the relevant
endpoint without regard to the corresponding bit in EPSTL, and returns a stall handshake (1-1 in
figure 25.19).
Once an internal status bit is set, it remains set until cleared by a Clear Feature command from the
host, without regard to the corresponding bit in EPSTL. After a bit is cleared by the Clear Feature
command, the corresponding bit in EPSTL is referenced (3-1 in figure 25.19). The USB function
controller continues to return a stall handshake while the internal status bit is set, since the internal
status bit is set even if a transaction is executed for the corresponding endpoint (2-1 and 2-2 in
figure 25.19). To clear a stall, therefore, the internal status bit must be cleared with a Clear Feature
command (3-1 in figure 25.19). In this time, if set by the application, the corresponding bit in
EPSTL should also be cleared (2-1 in figure 25.19).
Rev. 3.00 Jan. 18, 2008 Page 858 of 1458
REJ09B0033-0300
(1) Transition from normal operation to stall
(2) When transaction is performed when internal status bit is set, and Clear Feature is sent
(3) When Clear Feature is sent before transaction is performed
Automatic Stall by USB Function Controller
(1-1)
(2-1)
(2-2)
(3-1)
STALL handshake
Transaction request
STALL handshake
Clear Feature command
USB Function Controller (USBF)
Figure 25.19
Internal status bit
Internal status bit
Internal status bit
Internal status bit
Automatic Stall by USB Function Controller
0 → 1
1 → 0
1
1
Normal status restored
Stall status maintained
To (2-1) or (3-1)
EPnSTL
EPnSTL
EPnSTL
EPnSTL
0
0
0
0
1. In case of USB
1. EPnSTL cleared to
2. IN/OUT token
3. Internal status bit
4. EPnSTL not
5. Internal status bit
1. Transmission of
1. Internal status bit
2. EPnSTL not changed
specification
violation, etc., USB
function module
stalls endpoint
automatically
0 by application
received from host
already set to 1
referenced
not changed
STALL handshake
cleared to 0