usbdrv.h

USB Boot Loader for ATMega 8 通过软件方法实现USB功能

/* Name: usbdrv.h
 * Project: AVR USB driver
 * Author: Christian Starkjohann
 * Creation Date: 2004-12-29
 * Tabsize: 4
 * Copyright: (c) 2005 by OBJECTIVE DEVELOPMENT Software GmbH
 * License: Proprietary, free under certain conditions. See Documentation.
 * This Revision: $Id: usbdrv.h 158 2006-03-14 15:34:17Z cs $
 */

#ifndef __usbdrv_h_included__
#define __usbdrv_h_included__
#include "usbconfig.h"
#include "iarcompat.h"

/*
Hardware Prerequisites:
=======================
USB lines D+ and D- MUST be wired to the same I/O port. Line D- MUST be wired
to bit number 0. D+ must also be connected to INT0. D- requires a pullup of
1.5k to +3.5V (and the device must be powered at 3.5V) to identify as
low-speed USB device. A pullup of 1M SHOULD be connected from D+ to +3.5V to
prevent interference when no USB master is connected. We use D+ as interrupt
source and not D- because it does not trigger on keep-alive and RESET states.

As a compile time option, the 1.5k pullup resistor on D- can be made
switchable to allow the device to disconnect at will. See the definition of
usbDeviceConnect() and usbDeviceDisconnect() further down in this file.

Please adapt the values in usbconfig.h according to your hardware!

The device MUST be clocked at 12 MHz. This is more than the 10 MHz allowed by
an AT90S2313 powered at 4.5V. However, if the supply voltage to maximum clock
relation is interpolated linearly, an ATtiny2313 meets the requirement by
specification. In practice, the AT90S2313 can be overclocked and works well.


Limitations:
============
Compiling:
You should link the usbdrv.o module first because it has special alignment
requirements for the receive buffer (the buffer must not cross a 256 byte
page boundary, it must not even touch it at the end). If you can't link it
first, you must use other measures to ensure alignment.
Note: gcc does not always assign variable addresses in the order as the modules
are linked or the variables are declared. You can choose a memory section for
the receive buffer with the configuration option "USB_BUFFER_SECTION". This
option defaults to ".bss". If you use your own section, you can place it at
an arbitrary location with a linker option similar to
"-Wl,--section-start=.mybuffer=0x800060". Use "avr-nm -ng" on the binary and
search for "usbRxBuf" to find tbe base address of the 22 bytes rx buffer.

Robustness with respect to communication errors:
The driver assumes error-free communication. It DOES check for errors in
the PID, but does NOT check bit stuffing errors, SE0 in middle of a byte,
token CRC (5 bit) and data CRC (16 bit). CRC checks can not be performed due
to timing constraints: We must start sending a reply within 7 bit times.
Bit stuffing and misplaced SE0 would have to be checked in real-time, but CPU
performance does not permit that. The driver does not check Data0/Data1
toggling, but application software can implement the check.

Sampling jitter:
The driver guarantees a sampling window of 1/2 bit. The USB spec requires
that the receiver has at most 1/4 bit sampling window. The 1/2 bit window
should still work reliably enough because we work at low speed. If you want
to meet the spec, define the macro "USB_CFG_SAMPLE_EXACT" to 1 in usbconfig.h.
This will unroll a loop which results in bigger code size.

Input characteristics:
Since no differential receiver circuit is used, electrical interference
robustness may suffer. The driver samples only one of the data lines with
an ordinary I/O pin's input characteristics. However, since this is only a
low speed USB implementation and the specification allows for 8 times the
bit rate over the same hardware, we should be on the safe side. Even the spec
requires detection of asymmetric states at high bit rate for SE0 detection.

Number of endpoints:
The driver supports up to two endpoints: One control endpoint (endpoint 0) and
one interrupt-in endpoint (endpoint 1) where the device can send interrupt
data to the host. Endpoint 1 is only compiled in if
USB_CFG_HAVE_INTRIN_ENDPOINT is defined to 1 in usbconfig.h.

Maximum data payload:
Data payload of control in and out transfers may be up to 254 bytes. In order
to accept payload data of out transfers, you need to implement
'usbFunctionWrite()'.

USB Suspend Mode supply current:
The USB standard limits power consumption to 500uA when the bus is in suspend
mode. This is not a problem for self-powered devices since they don't need
bus power anyway. Bus-powered devices can achieve this only by putting the
CPU in sleep mode. The driver does not implement suspend handling by itself.
However, the application may implement activity monitoring and wakeup from
sleep. The host sends regular SE0 states on the bus to keep it active. These
SE0 states can be detected by wiring the INT1 pin to D+. It is not necessary
to enable the interrupt, checking the interrupt pending flag should suffice.
Before entering sleep mode, the application should enable INT1 for a wakeup
on the next bus activity.

Operation without an USB master:
The driver behaves neutral without connection to an USB master if D- reads
as 1. To avoid spurious interrupts, we recommend a high impedance (e.g. 1M)
pullup resistor on D+. If D- becomes statically 0, the driver may block in
the interrupt routine.

Interrupt latency:
The application must ensure that the USB interrupt is not disabled for more
than 20 cycles. This implies that all interrupt routines must either be
declared as "INTERRUPT" instead of "SIGNAL" (see "avr/signal.h") or that they
are written in assembler with "sei" as the first instruction.

Maximum interrupt duration / CPU cycle consumption:
The driver handles all USB communication during the interrupt service
routine. The routine will not return before an entire USB message is received
and the reply is sent. This may be up to ca. 1200 cycles = 100us if the host
conforms to the standard. The driver will consume CPU cycles for all USB
messages, even if they address another (low-speed) device on the same bus.

*/

/* ------------------------------------------------------------------------- */
/* --------------------------- Module Interface ---------------------------- */
/* ------------------------------------------------------------------------- */

#define USBDRV_VERSION  20060314
/* This define uniquely identifies a driver version. It is a decimal number
 * constructed from the driver's release date in the form YYYYMMDD. If the
 * driver's behavior or interface changes, you can use this constant to
 * distinguish versions. If it is not defined, the driver's release date is
 * older than 2006-01-25.
 */

#ifndef __ASSEMBLER__

#ifndef uchar
#define uchar   unsigned char
#endif
#ifndef schar
#define schar   signed char
#endif
/* shortcuts for well defined 8 bit integer types */

extern void     usbInit(void);
/* This function must be called before interrupts are enabled and the main
 * loop is entered.
 */
extern void     usbPoll(void);
/* This function must be called at regular intervals from the main loop.
 * Maximum delay between calls is somewhat less than 50ms (USB timeout for
 * accepting a Setup message). Otherwise the device will not be recognized.
 * Please note that debug outputs through the UART take ~ 0.5ms per byte
 * at 19200 bps.
 */
extern uchar    *usbMsgPtr;
/* This variable may be used to pass transmit data to the driver from the
 * implementation of usbFunctionWrite(). It is also used internally by the
 * driver for standard control requests.
 */
extern uchar    usbFunctionSetup(uchar data[8]);
/* This function is called when the driver receives a SETUP transaction from
 * the host which is not answered by the driver itself (in practice: class and
 * vendor requests). All control transfers start with a SETUP transaction where
 * the host communicates the parameters of the following (optional) data
 * transfer. The SETUP data is available in the 'data' parameter which can
 * (and should) be casted to 'usbRequest_t *' for a more user-friendly access
 * to parameters.
 *
 * If the SETUP indicates a control-in transfer, you should provide the
 * requested data to the driver. There are two ways to transfer this data:
 * (1) Set the global pointer 'usbMsgPtr' to the base of the static RAM data
 * block and return the length of the data in 'usbFunctionSetup()'. The driver
 * will handle the rest. Or (2) return 0xff in 'usbFunctionSetup()'. The driver
 * will then call 'usbFunctionRead()' when data is needed. See the
 * documentation for usbFunctionRead() for details.
 *
 * If the SETUP indicates a control-out transfer, the only way to receive the
 * data from the host is through the 'usbFunctionWrite()' call. If you
 * implement this function, you must return 0xff in 'usbFunctionSetup()' to
 * indicate that 'usbFunctionWrite()' should be used. See the documentation of
 * this function for more information. If you just want to ignore the data sent
 * by the host, return 0 in 'usbFunctionSetup()'.
 *
 * Note that calls to the functions usbFunctionRead() and usbFunctionWrite()
 * are only done if enabled by the configuration in usbconfig.h.
 */
#if USB_CFG_HAVE_INTRIN_ENDPOINT
void    usbSetInterrupt(uchar *data, uchar len);
/* This function sets the message which will be sent during the next interrupt
 * IN transfer. The message is copied to an internal buffer and must not exceed
 * a length of 8 bytes. The message may be 0 bytes long just to indicate the
 * interrupt status to the host.
 * If you need to transfer more bytes, use a control read after the interrupt.
 */
extern volatile schar usbTxLen1;
#define usbInterruptIsReady()   (usbTxLen1 == -1)
/* This macro indicates whether the last interrupt message has already been
 * sent. If you set a new interrupt message before the old was sent, the
 * message already buffered will be lost.
 */
#endif /* USB_CFG_HAVE_INTRIN_ENDPOINT */
#if USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH
extern PROGMEM const char usbHidReportDescriptor[];
/* If you implement an HID device, you need to provide a report descriptor.
 * The HID report descriptor syntax is a bit complex. If you understand how
 * report descriptors are constructed, we recommend that you use the HID
 * Descriptor Tool from usb.org, see http://www.usb.org/developers/hidpage/.
 * Otherwise you should probably start with a working example.
 */
#endif  /* USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH */
#if USB_CFG_IMPLEMENT_FN_WRITE
extern uchar    usbFunctionWrite(uchar *data, uchar len);
/* This function is called by the driver to provide a control transfer's
 * payload data (control-out). It is called in chunks of up to 8 bytes. The
 * total count provided in the current control transfer can be obtained from
 * the 'length' property in the setup data. If an error occurred during
 * processing, return 0xff (== -1). The driver will answer the entire transfer
 * with a STALL token in this case. If you have received the entire payload
 * successfully, return 1. If you expect more data, return 0. If you don't
 * know whether the host will send more data (you should know, the total is
 * provided in the usbFunctionSetup() call!), return 1.
 * NOTE: If you return 0xff for STALL, 'usbFunctionWrite()' may still be called
 * for the remaining data. You must continue to return 0xff for STALL in these
 * calls.
 * In order to get usbFunctionWrite() called, define USB_CFG_IMPLEMENT_FN_WRITE
 * to 1 in usbconfig.h and return 0xff in usbFunctionSetup()..
 */
#endif /* USB_CFG_IMPLEMENT_FN_WRITE */
#if USB_CFG_IMPLEMENT_FN_READ
extern uchar usbFunctionRead(uchar *data, uchar len);
/* This function is called by the driver to ask the application for a control