How to send and receive a couple of 'special' out-of-band information to a device? tud_vendor_control_xfer_cb

[ccrome]

Hi there, I'm trying to work out what the correct way to send and receive a couple of bytes to the control endpoint with a vendor request. I have the following code, which seems to work, and I was wondering if the tud_control_xfer was in the right place. I assumed the right place would be in CONTROL_STAGE_DATA, but that doesn't actually work. What works is to put the tud_control_xfer in the SETUP, both for IN and OUT transactions.

This code works:

uint8_t to_send[6] = {0, 1, 2, 3, 4, 5};
bool custom_command_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request) {
    bool result = false;

    if (rhport != BOARD_TUD_RHPORT)
        return result;

    if (request->bmRequestType_bit.direction == TUSB_DIR_IN) {
        // TUSB_DIR_IN                                                                                                                                                                                             
        switch (stage) {
        case CONTROL_STAGE_SETUP:
            result = tud_control_xfer(rhport, request, &to_send, sizeof(to_send));
            break;
        case CONTROL_STAGE_DATA:
            result = true;
            break;
        case CONTROL_STAGE_ACK:
            result = true;
            break;
        default:
            break;
        }
    } else {
        // TUSB_DIR_OUT                                                                                                                                                                                            
        switch (stage) {
        case CONTROL_STAGE_SETUP:
            result = tud_control_xfer(rhport, request, &to_send, sizeof(to_send));
            break;
        case CONTROL_STAGE_DATA:
            result = true;
            break;
        case CONTROL_STAGE_ACK:
            // modify the received data, just to see that something is happening when it's transmitted                                                                                                             
            for (uint32_t i = 0; i < sizeof(to_send); i++)  {
                to_send[i] |= 0x30;
            }
            result = true;
            break;
        default:
            break;
        }
    }
    return result;
}

bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_request_t const * request) {
    bool result = false;
    switch (request->bmRequestType_bit.type) {
    case TUSB_REQ_TYPE_VENDOR:
        switch (request->bRequest) {
        case VENDOR_REQUEST_CUSTOM_COMMAND:
            result = custom_command_cb(rhport, stage, request);
            break;
        }
        break;
    case TUSB_REQ_TYPE_STANDARD:
        break;
    case TUSB_REQ_TYPE_CLASS:
        break;
    default:
        break;
    }
    return result;
}

Assuming this is correct, I can add an example with host side too so people have a place to reference an implementation like this.

[hathach]

tud_vendor_control_xfer_cb() is called when a transaction is complete e.g if

• stage = SETUP -> setup stage is complete token SETUP is sent and ACK
• stage = DATA -> data stage is complete, all data is transfered
• stage = ACK -> status stage is complete, the whole control is complete

so if you want to transfer data, you must preare that in setup stage.