Renesas CPU Board M3A-HS19 Uživatelský manuál stáhnout pdf (Strana 8)

SH7285/SH7286 USB Function Module

USB to Serial Conversion Application Note

2.4.1 Setup Stage

The Setup stage is composed of one setup transaction. The USB host sends a setup token or data packet (USB

command), then returns a handshake in response to the data packet (USB command) that the USB device received.

Figure 2.5 shows the Setup Transaction Flowchart.

The USB function module automatically executes the Setup stage, Data stage, and Status stage in response to the USB

requests (with some exceptions). If the received request is not a USB standard request, the USB function module

holds the received request in the EP0S data register (USBEPDR0S), and generates

the setup request receive complete

interrupt

using the SETUPTS bit in the USBIFR0 register.

The sample program reads the USB request held in the data register (USBEPDR0S) during the interrupt, and decodes

the USB request to determine how to process subsequent stages.

If the decoded USB request is a request to execute

the control IN transfer, the sample program writes the first data to transfer to the USB host in the EP0iFIFO and the

interrupt is completed.

Figure 2.6 shows an operation chart of the sample program. The function (DecComCommand)

processes USB communication class requests in the sample program.

Idle

SETUP

DATA0

ACK

Idle

Token

Data (USB command)

Handshake

Packet issued by the host

Packet issued by the device

Figure 2.5 Setup Transaction Flowchart

REJ05B1152-0100/Rev.1.00 May 2008 Page 8 of 35

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Renesas CPU Board M3A-HS19 Uživatelský manuál Strana 8