// Assumption: The user has previously called usbComRxAvailable and its return value
// was greater than or equal to size.
void usbComRxReceive(uint8 XDATA* buffer, uint8 size)
{
usbReadFifo(CDC_DATA_ENDPOINT, size, buffer);
if (USBCNTL == 0)
{
USBCSOL &= ~USBCSOL_OUTPKT_RDY; // Tell the USB module we are done reading this packet, so it can receive more.
}
}
void usbPoll()
{
uint8 usbcif;
uint8 usbiif;
//uint8 usboif = USBOIF;
if (!usbPowerPresent())
{
// The VBUS line is low. This usually means that the USB cable has been
// disconnected or the computer has been turned off.
SLEEP &= ~(1<<7); // Disable the USB module (SLEEP.USB_EN = 0).
disableUsbPullup();
usbDeviceState = USB_STATE_DETACHED;
usbSuspendMode = 0;
return;
}
if (usbDeviceState == USB_STATE_DETACHED)
{
enableUsbPullup();
SLEEP |= (1<<7); // Enable the USB module (SLEEP.USB_EN = 1).
__asm nop __endasm; // Datasheet doesn't say so, but David suspects we need some NOPs here before writing to USB registers.
__asm nop __endasm;
__asm nop __endasm;
__asm nop __endasm;
usbDeviceState = USB_STATE_POWERED;
basicUsbInit();
}
usbcif = USBCIF;
usbiif = USBIIF;
if (usbcif & (1<<0)) // Check SUSPENDIF
{
// The bus has been idle for 3 ms, so we are now in Suspend mode.
// It is the user's responsibility to check usbSuspended() and go to sleep (PM1)
// if necessary.
usbSuspendMode = 1;
}
if (usbcif & (1<<2)) // check RSTIF, the reset flag
{
// A USB reset signal has been received.
usbDeviceState = USB_STATE_DEFAULT;
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
basicUsbInit();
}
if (usbcif & (1<<1)) // Check RESUMEIF
{
usbSuspendMode = 0;
}
if (usbiif & (1<<0)) // Check EP0IF
{
// Something happened on Endpoint 0, the endpoint for control transfers.
uint8 usbcs0;
USBINDEX = 0;
usbcs0 = USBCS0;
usbActivityFlag = 1;
if (usbcs0 & (1<<4)) // Check SETUP_END
{
// A new setup packet has arrived, prematurely ending the previous control transfer.
USBCS0 = 0x80; // Clear the SETUP_END bit
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
}
if (usbcs0 & (1<<2)) // Check SENT_STALL
{
// A STALL packet was sent
USBCS0 = 0x00; // Reset endpoint 0.
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
}
if (usbcs0 & (1<<0)) // Check OUTPKT_RDY
{
// Requirement: Every codepath from here must result in writing a 1 to
// bit 6 of USBCS0 to clear the OUTPKT_RDY flag: USBCS0 = (1<<6).
if (controlTransferState == CONTROL_TRANSFER_STATE_WRITE)
{
// A data packet has been received as part of a control write transfer.
uint8 bytesReceived = USBCNT0;
if (bytesReceived > controlTransferBytesLeft)
{
bytesReceived = controlTransferBytesLeft;
}
usbReadFifo(0, bytesReceived, controlTransferPointer);
controlTransferPointer += bytesReceived;
controlTransferBytesLeft -= bytesReceived;
if (controlTransferBytesLeft)
{
// Arm the endpoint to receive more bytes
USBCS0 = (1<<6); // De-asserts the OUTPKT_RDY bit (bit 0).
}
else
{
// The host has sent all the data we were expecting.
if (usbSetupPacket.requestType != USB_REQUEST_TYPE_STANDARD) // OPT: remove this check
{
usbCallbackControlWriteHandler();
}
USBINDEX = 0; // Just in case USBINDEX was changed above.
if (controlTransferState == CONTROL_TRANSFER_STATE_NONE)
{
// The data received was invalid.
USBCS0 = (1<<6) | (1<<3) | (1<<5); // clear OUTPKT_RDY, set DATA_END, SEND_STALL
}
else
{
// The data received was valid.
USBCS0 = (1<<6) | (1<<3); // clear OUTPKT_RDY, set DATA_END
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
}
}
}
else if (USBCNT0 == 8)
{
// A SETUP packet has been received from the computer, starting a new
// control transfer.
usbReadFifo(0, 8, (uint8 XDATA *)&usbSetupPacket); // Store the data in usbSetupPacket.
// Wipe out the information about the last control transfer.
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
if (usbSetupPacket.requestType == USB_REQUEST_TYPE_STANDARD)
{
// The request_type field indicates that this is a Standard Device Request
// as described in USB2.0 Chapter 9.4 Standard Device Requests.
// These requests are handled by the library in the function below.
usbStandardDeviceRequestHandler();
}
else
{
// Otherwise, we use this callback so the user can decide how to handle the
// setup packet. In this callback, the user can call various helper
// functions that set controlTransferState.
usbCallbackSetupHandler();
}
USBINDEX = 0; // Select EP0 again because the functions above might have changed USBINDEX.
// Modify the count so that we don't send more data than the host requested.
if(controlTransferBytesLeft > usbSetupPacket.wLength)
{
controlTransferBytesLeft = usbSetupPacket.wLength;
}
// Prepare for the first transaction after the SETUP packet.
if (controlTransferState == CONTROL_TRANSFER_STATE_NONE)
{
// This is invalid/unrecognized control transfer, so send a STALL packet.
USBCS0 = (1<<6) | (1<<5); // Clears the OUTPKT_RDY flag because we've handled it, and sends a STALL.
}
else if (controlTransferState == CONTROL_TRANSFER_STATE_WRITE)
{
if (controlTransferBytesLeft)
{
// Arm the endpoint to receive the first data packet of a control write transfer.
USBCS0 = (1<<6); // De-asserts the OUTPKT_RDY bit.
}
else
{
// Acknowledge a control write transfer with no data phase.
USBCS0 = (1<<6) | (1<<3) | (1<<1); // De-asserts OUTPKY_RDY, asserts DATA_END, asserts INPKT_RDY.
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
}
}
}
else
{
// An OUT packet was received on Endpoint 0, but we are not in the middle of a
// control write transfer and it was not the right length to be a setup packet.
// This situation is not expected.
USBCS0 = (1<<6); // De-asserts the OUTPKT_RDY.
}
}
if (!(usbcs0 & (1<<1)) && (controlTransferState == CONTROL_TRANSFER_STATE_READ))
{
// We are doing a control read transfer, and Endpoint 0 is ready to accept another
// IN packet to send to the computer.
uint8 bytesToSend;
if (controlTransferBytesLeft < USB_EP0_PACKET_SIZE)
{
// Send the last packet (might be an empty packet).
usbcs0 = (1<<1)|(1<<3); // INPKT_RDY and DATA_END
bytesToSend = controlTransferBytesLeft;
controlTransferState = CONTROL_TRANSFER_STATE_NONE;
}
else
{
// Send a packet.
usbcs0 = (1<<1); // INPKT_RDY
bytesToSend = USB_EP0_PACKET_SIZE;
}
// Arm endpoint 0 to send the next packet.
usbWriteFifo(0, bytesToSend, controlTransferPointer);
USBCS0 = usbcs0;
// Update the control transfer state.
controlTransferPointer += bytesToSend;
controlTransferBytesLeft -= bytesToSend;
}
}
}