OS? Language? SD card access library? Version numbers? :-) It's been too long since I Arduio-anything'ed to have any specific hints up my sleeve regarding environment etc. I'll take a stab or two from a hardware point of view. I have no clue as to what SD card read/erase/write cycle times might be, so some of the following may not apply.
Is it at all possible you (or another thread) is polling the RTC or servicing RTC interrupts while the read/modify/write is occurring? Assuming the RTC is also an SPI device it might disrupt the SD card update operation, likely made up of discrete read + modify/erase + write operations. This will typically take on the order of milliseconds, at least with "classic" SPI/I2C EEPROM/NVRAM chips. Even if it worked as-is I'd strongly suggest keeping the string in RAM, and only write a copy of it to the SD card after each update. Take proper care to re-init the RAM copy from SD card at start-up, etc. NealS _______________________________________________ PLUG mailing list PLUG@lists.pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug
