USB Peripheral Mass Storage Class (r_usb_pmsc)

This module provides a USB Peripheral Mass Storage Class (PMSC) driver. It implements the USB PMSC Interface.

Functions

Refer to USB (r_usb_basic) for the common API (r_usb_basic) to be called from the application.

Detailed Description

Overview

The r_usb_pmsc module combines with the r_usb_basic module to provide USB Peripheral It operates as a Mass Storage class driver (hereinafter referred to as PMSC).
The USB peripheral mass storage class driver (PMSC) comprises a USB mass storage class bulk-only transport (BOT) protocol.
When combined with a USB peripheral control driver and media driver, it enables communication with a USB host as a BOT-compatible storage device.

Features

The r_usb_pmsc module has the following key features:

• Storage command control using the BOT protocol
• Supports SFF-8070i (ATAPI)
• Response to mass storage device class requests from a USB host

Configuration

Build Time Configurations for r_usb_pmsc

The following build time configurations are defined in fsp_cfg/r_usb_pmsc_cfg.h:

Configuration	Options	Default	Description
Bulk Input Transfer Pipe	USB PIPE1 USB PIPE2 USB PIPE3 USB PIPE4 USB PIPE5	USB PIPE1	Select the USB pipe to use for bulk input transfers.
Bulk Output Transfer Pipe	USB PIPE1 USB PIPE2 USB PIPE3 USB PIPE4 USB PIPE5	USB PIPE2	Select the USB pipe to use for bulk output transfers.
Vendor Information	Vendor Information must be 8 bytes long; pad with spaces if shorter.	Vendor	Specify the vendor information field (part of the Inquiry command response).
Product Information	Product Information must be 16 bytes long; pad with spaces if shorter.	Mass Storage	Specify the product information field (part of the Inquiry command response).
Product Revision Level.	Product Revision Level must be 4 bytes long; pad with spaces if shorter.	1.00	Specify the product revision level field (part of the Inquiry command response).
Number of Transfer Sectors	Please enter a number between 1 and 255.	8	Specify the maximum sector size to request with one data transfer.

Configurations for Connectivity > USB PMSC (r_usb_pmsc)

This module can be added to the Stacks tab via New Stack > Connectivity > USB PMSC (r_usb_pmsc).

Configuration	Options	Default	Description
Name	Name must be a valid C symbol	g_pmsc0	Module name.

Refer to the USB (r_usb_basic) module for hardware configuration options.

Clock Configuration

Refer to the USB (r_usb_basic) module.

Pin Configuration

Refer to the USB (r_usb_basic) module.

Usage Notes

Class Requests

The class requests supported by this driver are shown below.

Request	Code	Description
Bulk-Only Mass Storage Reset	0xFF	Resets the connection interface to the mass storage device.
Get Max Logical Unit Number	0xFE	Reports the logical numbers supported by the device.

Storage Commands

This driver supports the following storage commands.

Command	Code	Description
TEST_UNIT_READY	0x00	Checks the state of the peripheral device.
REQUEST_SENSE	0x03	Gets the error information of the previous storage command execution result.
INQUIRY	0x12	Gets the parameter information of the logical unit.
READ_FORMAT_CAPACITY	0x23	Gets the formattable capacity.
READ_CAPACITY	0x25	Gets the capacity information of the logical unit.
READ10	0x28	Reads data.
WRITE10	0x1A	Writes data.
MODE_SENSE10	0x5A	Gets the parameters of the logical unit.

Note

A STALL or FAIL error is sent to the host upon receipt of any command not listed in the above table.

BOT Protocol Overview

BOT (USB MSC Bulk-Only Transport) is a transfer protocol that encapsulates command, data, and status (results of commands) using only two endpoints (one bulk in and one bulk out). The ATAPI storage commands and the response status are embedded in a Command Block Wrapper (CBW) and a Command Status Wrapper (CSW). The below image shows an overview of how the BOT protocol progresses with command and status data flowing between USB host and peripheral.

BOT protocol Overview

Block Media Interface

PMSC implements a block media interface to enable access to higher-level modules. If the block media interface supports multiple media, users can select any media to access.

Note

When the user develops the storage media driver, be sure to define the instance named "g_rm_block_media0".

Limitations

1. The driver always returns 0 in response to the GetMaxLun command.
2. The driver supports a sector size of 512 bytes only.
3. The only media currently supported by the block media interface is an SD card. The card must be inserted before initializing the driver.
4. When using DMA for Hi-Speed transfers continuous transfer mode must not be used in the USB Basic driver.
5. The storage area must be formatted before use.
6. When using the SD/MMC Block Media Implementation (rm_block_media_sdmmc), "Card Detection" must be set to "Not Used" in the SD/MMC Host Interface (r_sdhi) settings.
7. The driver does not support Low-speed.

Examples

USB PMSC Example

In this example, when the evaluation board is connected to the host PC it is recognized as a removable disk and reading/writing files is possible. The FAT type is either FAT12, FAT16, or FAT32 depending on the size of the media used.

Example Operating Environment

void usb_pmsc_example (void)
{
    usb_event_info_t usb_event;
#if (BSP_CFG_RTOS == 2)
    usb_event_info_t * p_mess;
#else
    usb_status_t event;
#endif

    g_usb_on_usb.open(&g_basic0_ctrl, &g_basic0_cfg);


    /* Loop back between PC(TerminalSoft) and USB MCU */
    while (1)
    {
#if (BSP_CFG_RTOS == 2)
        USB_APL_RCV_MSG(USB_APL_MBX, (usb_msg_t **) &p_mess);
        usb_event = *p_mess;

        /* Analyzing the received message */
        switch (usb_event.event)
#else                                  /* (BSP_CFG_RTOS == 2) */

        g_usb_on_usb.eventGet(&usb_event, &event);

        switch (event)
#endif                                 /* (BSP_CFG_RTOS == 2) */
        {
            case USB_STATUS_CONFIGURED:
            {
                break;
            }

            case USB_STATUS_SUSPEND:
            case USB_STATUS_DETACH:
            {
#if USB_SUPPORT_LPW == USB_APL_ENABLE

// @@                low_power_mcu();
#endif                                 /* USB_SUPPORT_LPW == USB_APL_ENABLE */
                break;
            }

            default:
            {
                break;
            }
        }
    }
}                                      /* End of function usb_main() */

Descriptor

A template for PMSC descriptors can be found in ra/fsp/src/r_usb_pmsc/r_usb_pmsc_descriptor.c.template. Also, please be sure to use your vendor ID.