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(Sorry for my limited English ability.)
I have been assigned to develop an USB based I/O board (software portion). The requirement of this I/O board has never been discussed and never been defined, and the hardware has not been made. So I am working on the LPC23xx evaluation boards. What I have been told is that, this USB based I/O board is made to work with a X86 platform running Linux.
I read some Tsuneo's (Tsuneo Chinzei) articles, and eventually decided to choose the LPCUSB for my LPC2378 evaluation board. The major reasons are: 1. Tsuneo said that it is the best open source project for LPC23xx. 2. Its Linux driver is ready. (The standard one in the Linux kernel.)
I built a Cygwin/YAGARTO GNU ARM toolchain environment to perform some simple tests for LPCUSB. And found that, the main_serial.c works. Then, I migrated the LPCUSB to the KEIL environment, and the main_serial.c still works. But during the migrations and the tests, I found that, or I guessed that, the LPCUSB USB stack is good; however, its examples are only for demonstrating purpose, so they are not well tested.
The major problem for me currently is that, the [static void USBFrameHandler(U16 wFrame)] function does not work properly, because the [fBulkInBusy] variable has never been reset to FALSE. Actually, the real circumstance is: If I send one byte from the X86 desktop to the LPC2378 board, the LPC2378 can send one byte back to the X86 desktop. If I do not send one byte from the X86 desktop to the LPC2378 board, then the LPC2378 board can not send anything to the X86 desktop. I am not so sure that, it is a bug that I have to fix, or it is not a bug, I just need to implement some more USB functions to complete the mechanism.
I don't actually know that, how it works originally. Is that the host sends data with a BulkOut, and this BulkOut invokes a BulkIn? Or the LPC2378 board sends data to the host when it is polled every milisecond by the host? What is the correct way to send data from the LPC2378 board to the host?
Is there any USB-CDC tutorial for a novice? Or could someone please kindly provide some advices?
John,
why the function is called after the DATA Packet had been sent? why not called before the DATA Packet had been sent?
as stated above, IN is in terms of the host, thus data flowing from the device to the host. it is AFTER the packet has been sent because it has to be: FIRST, you write something in reply to the host, and then BulkIn gets called to give you the chance to deliver more data. that's how it works. BulkIn will never be called unless you first wrote something to the bus!
and I don't think your technique is an issue at all - quite the contrary. your questions indicate depth and an eager to learn, certainly in comparisons the common "do my homework" poster!