HD6417727BP160CV Datasheet, PDF (778/1098 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/ SH7700 Series

Section 23 USB Function Controller
23.8.3 Automatic Stall by USB Function Module
When a stall setting is made with the Set Feature command, or in the event of a USB specification
violation, the USB function module automatically sets the internal status bit for the relevant
endpoint without regard to the USBEPSTL register, and returns a stall handshake (1-1 in figure
23.14).
Once an internal status bit is set, it remains set until cleared by a Clear Feature command from the
host, without regard to the USBEPSTL register. After a bit is cleared by the Clear Feature
command, USBEPSTL is referenced (3-1 in figure 23.14). The USB function module 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 23.14). To clear a
stall, therefore, the internal status bit must be cleared with a Clear Feature command (3-1 in figure
23.14). If set by the application, USBEPSTL should also be cleared (2-1 in figure 23.14).
Rev.6.00 Mar. 27, 2009 Page 720 of 1036
REJ09B0254-0600