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Hi, Following are my questions: 1. I use 128K version of 80C51 and define common area (0-3fff) and 2 other banks. from (4000 - ffff) When I define a font table (array) in one bank. After compilation, I found the common area grows, seems like it relocate the font array into the common area instead of the bank area. 2. I am working on video application, I have a display v-sync interrupt every 1/60 sec. If I stay in this interrupt too long (> 1.5 ~ 2 ms) system hang up. if short delay (1 ms) then everything works fine. Any idea? I know interrupt should be as short as possible but is there any restriction on how long can we stay in interrupt service routine? Really appreciate if someone can help me on these issues. Thanks
seems like it relocate the font Don't guess --- check. Look into the map files to see where that array actually ended up. I know interrupt should be as short as possible but is there any restriction on how long can we stay in interrupt service routine? It's really quite simple: make it as short as possible, and if you get a hang-up, make it even shorter. There's not fixed upper limit, per se, other than you obviously can't allow the interrupt handler to take longer than the time between two interrupts... And what on earth are you doing in an IRQ handler that takes an entire millisecond? [And please: don't post several unrelated questions in the same article --- one subject per posting/thread is the idea]