Dear Mark,

LPC9xx family micros provide a bit diffrent kind of code security than standar 80C51 micros. If you set lock bit 1 MOVC instructions are barred. For each sector [ with LPC922 there are 8 sectors each 1kb ] there is a set of three lock bits.

You can keep your LUT [ Constants ] in a separate sector say sector 7 and rest of the code in other sectors. Then set lock bit for code sectors and leave constant section unlocked.

Dont leave a device compeltely unlocked though these devices dont allow reading the internal data/code using ISP or programmers even if all lock bits open. But it is possible by other techniques to steal the code. For example a theif may overwrite your sector 0 with his own code that reads your sector 1 to 7 using MOVC and sends it using serial port.

regards,
Prahlad Purohit