MPC8280 datasheet(851/1386 Pages) FREESCALE

851 / 1386 page

Universal Serial Bus Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

27-35

24. Write 0x80 to USCOM to start filling the Tx FIFO with endpoint 1 data ready for transmission

when an IN token is received.

25. Write 0x81 to USCOM to start filling the Tx FIFO with endpoint 2 data ready for transmission

when an IN token is received.

26. Generate an IN token to address 5, endpoint number 0, control.

27. Generate an IN token to address 5, endpoint number 7, bulk.

27.10 Programming the USB Host Controller (Packet-Level)

The MPC8280 implementation of a USB host uses the endpoint represented by USEP1 to control the host

transmission and reception. The other endpoints are typically not used, except for testing purposes

(loop-back).

Programming the USB controller to act as host is similar to configuring an endpoint for function operation.

A general outline of how to program the host controller follows. (A more detailed example can be found

in Section 27.10.1, “USB Host Controller Initialization Example.”)

•

Set the host bit in the mode register (USBMOD[HOST] = 1) to configure the controller as a host.

•

Set the multi-frame bit in the endpoint configuration register (USEP1[MF] = 1) to allow

SETUP/OUT tokens and DATA0/DATA1 packets to be sent back-to-back.

•

Prepare tokens in separate BDs.

•

Using software, append the CRC5 as part of the transmitted data because the CPM does not support

automatic CRC5 generation.

•

Clock the USB host controller as a high speed function (48-MHz reference clock).

•

For low-speed transactions with an external hub, set TxBD[LSP] in the token’s BD. This causes

the USB host controller to generate a preamble (PRE token) at full speed before changing the

transmit rate to low speed and sending the data packet. After completion of the transaction, the host

returns to full-speed operation. Note that LSP should be set only for token BDs.

27.10.1 USB Host Controller Initialization Example

The following is a local loopback example initialization sequence for the USB controller operating as a

host. It can be used to set up the host endpoint and one function endpoint to demonstrate an IN token

transaction.

1. Program CMXSCR to provide a 48 MHz clock to the USB controller.

2. Program the Port Registers to select USBRXD, USBRXP, USBRXN, USBTXP, USBTXN, and

USBOE.

3. Write (DPRAM+0x500) to EP1PTR, (DPRAM+0x520) to EP2PTR to set up the endpoint pointers.

4. Write 0x0000_0020 to DPRAM+0x500 to set up the RBASE and TBASE fields of the host

endpoint parameter RAM.

5. Write 0x1818_0100 to DPRAM+0x504 to set up the RFCR, TFCR, and MRBLR fields of the host

endpoint parameter RAM.

MPC8280 Datasheet(PDF) 851 Page - Freescale Semiconductor, Inc

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