Following set: Two identical PCBs (my hardware design using the LPC932), one with the "real" MCU, other with connector adaptor to EPM900 board. My software runs smooth on the emulator. I always send 24 bytes via COM5 (virtual COM port of FTDI232 USB-to-RS232 chip). The MCU processes the 24 bytes, executes a command, some routines and sends 24 bytes back to PC. The 24 bytes are a certain telegram with a two byte header and a checksum at the end. So far, so good. As I said, it runs smooth on the emu. But when I flash the compiled hex file into the LPC932 on the other board and connect this board with USB (COM5), I can send the 24 bytes to COM5, but I receive an error code generated by my firmware telling me the header is wrong. I found out that the last, the 24th byte, is somehow coming to the first position of the serial input buffer. Example: PC sends: AA 55 00 FF .... FF 60 hardware should have: AA 55 00 FF ... FF 60 in the 24 byte input buffer, but it has: 60 AA 55 00 FF ... FF No idea. Code is fine, I worked it out a thousand time. The whole buffer seems to be shifted. I repeat, this runs correct on the emu, which holds the same MCU. The worst fact is, that sometimes the code in the "real" MCU runs correctly after being connected to supply voltage (USB), sometimes it doesn't. So the code must be ok. Any clue? Thanks for any help.
As you can see in the code example above unreadable because you did not use pre and /pre also, there is no indication what is int and what is char. Int used in both an ISR and main is one of the most "popular" causes of "this proven well working program fails, it can not be my code" As I told before, I have a function which clears the I/O buffer with zeros at startup What does that achieve if the pointer is wrong when the first char is written. Erik
Sorry, Erik, I don't use this forum very much so I didn't remember that 'pre' thingy. But the code should be readable even on green. ;O) About the pointer: I'm not as stupid as I may sound, but when I set a pointer to a certain address BEFORE I write a byte into this address, the pointer can't be wrong. We don't speak about a mysterious device with commonly unexpected and unlogical behaviour, we speak about a microcontroller. It has to work, else it's not worth the money.