Renesas CPU Board M3A-HS19 Manuel d'utilisateur télécharger pdf (Page 14)

SH7285/SH7286 USB Function Module

USB to Serial Conversion Application Note

2.4.3 Status Stage

The direction of the data transaction in the Status stage differs from that of the Data stage; the data OUT transaction is

executed during the Status stage of the control IN transfer, and the data OUT transaction is executed during the Status

stage of the control OUT transfer.

(1) Status Stage of the Control IN Transfer

The USB host sends an OUT token and a 0-byte data packet. The USB device first receives the OUT token and then

receives the 0-byte data packet. Then, it returns an ACK handshake to the USB host.

The USB function module receives the OUT token and the 0-byte data packet, and automatically sends an ACK

handshake to the USB host. Then, the USB function module generates the data receive complete interrupt using the

EP0oTS bit in the USBIFR0 register.

The sample program sets the

EP0oFIFO read complete bit (USBTRG/EP0oRFDN) during an interrupt to wait for the

next interrupt.

Figure 2.11 shows an operation flowchart of the control IN transfer by the sample program.

Figure 2.11 Status Stage (Control IN Transfer)

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Renesas CPU Board M3A-HS19 Manuel d'utilisateur Page 14