USB数据的读写

[rooky123]

function USBdevRead(var usb: TLIBUSB; cmd, para1, para2, len: integer): boolean;
begin
if usb.handle = nil then
begin
Result := False;
Exit;
end;
if usb_control_msg(usb.handle, USB_TYPE_VENDOR or USB_RECIP_DEVICE or
USB_ENDPOINT_IN, cmd, para1, para2, usb.dat, len, USB_TIMEOUT) < 0 then
Result := False
else
Result := True;
end;

function USBdevWrite(var usb: TLIBUSB; cmd, para1, para2, len: integer): boolean;
begin
if usb.handle = nil then
begin
Result := False;
Exit;
end;
if usb_control_msg(usb.handle, USB_TYPE_VENDOR or USB_RECIP_DEVICE or
USB_ENDPOINT_OUT, cmd, para1, para2, usb.dat, len, USB_TIMEOUT) < 0 then
Result := False
else
Result := True;
end;



这个是两个读和写的函数,现在写可以了,但是读我读不到数据,就是对里面的参数不大懂,到底应该怎么传才是对的
比如我写是用USBdevWrite(USBasp, 1, 0, 0, 8);可以到数据发送出去
但是我用USBdevRead(USBasp, 0, 0, 0, 4)读取4个字节的数据就不成功,但是把4改成0就可以读成功了,但是没有数据,是不是读成功后我的数据就发在usb.dat,参数应该怎么传才对呢?

[xxgamexx]

关注！

[bdc995]

usb的固件是不是有问题呢？

[rooky123]

USB 芯片是使用的D12,硬件是没有问题的,使用周立功的那个USBDEBUG都没有问题,发过去了,能看到收到的数据

我的意思不是发送和接收有问题了,而是usb_control_msg这个函数的各个参数的使用方法

[heeten]

up

[sharp99827]

/**
* usb_control_msg - Builds a control urb, sends it off and waits for completion
* @dev: pointer to the usb device to send the message to
* @pipe: endpoint "pipe" to send the message to
* @request: USB message request value
* @requesttype: USB message request type value
* @value: USB message value
* @index: USB message index value
* @data: pointer to the data to send
* @size: length in bytes of the data to send
* @timeout: time in msecs to wait for the message to complete before
* timing out (if 0 the wait is forever)
* Context: !in_interrupt ()
*
* This function sends a simple control message to a specified endpoint
* and waits for the message to complete, or timeout.
*
* If successful, it returns the number of bytes transferred, otherwise a negative error number.
*
* Don't use this function from within an interrupt context, like a
* bottom half handler. If you need an asynchronous message, or need to send
* a message from within interrupt context, use usb_submit_urb()
* If a thread in your driver uses this call, make sure your disconnect()
* method can wait for it to complete. Since you don't have a handle on
* the URB used, you can't cancel the request.
*/
int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
__u16 value, __u16 index, void *data, __u16 size, int timeout)

[ko_navy]

mark

[winli3278]

我也遇到了相同的问题，read 时 usb_control_msg函数总是返回 －32错误。楼主解决这个问题了吗？？

[rilon1988]

关注

[big_chen]

你们遇到的问题都还不是很严重，我用usb_control_msg时,usb_device指针本身代表的地址值前后都不一样了,结果应该可想而知,到现在问题还没有解决,严重郁闷中...