Hi Joerg, >-----Original Message----- >From: Joerg Wunsch [mailto:j...@uriah.heep.sax.de] >Sent: Tuesday, March 23, 2010 2:24 AM >To: avr-libc-dev@nongnu.org >Cc: Boyapati, Anitha >Subject: Re: [avr-libc-dev] Bug #28901 - GPIO_t and CPU_t definitions > >Hi Anitha, > >> 1. What purpose do GPIO and CPU definitions serve? > >As far as I understand (disclaimer: I didn't do much with Xmegas so >far), they are just IO register blocks as any other IO register block >in the Xmega. If you look into the Xmega A datasheet, chapter 3 (AVR >CPU), there is a section "Register Summary" at the end of that >chapter, describing the IO registers that belong to the CPU block >(SREG, stack pointer etc.). >
>Likewise, the GPIO register block is described in section 4.18. Yes. This is a lot useful. > GPIO >registers are not tied to any hardware pin, their sole purpose is that >they are available to the CPU with faster instructions (IN, OUT, CBI, >SBI) than generic memory access (LD, ST) so they could be (ab)used as >fast "bit memory". (I'm not sure whether you could possibly include >them into the Xmega event system.) I'll look into this further Thanks Anitha _______________________________________________ AVR-libc-dev mailing list AVR-libc-dev@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-libc-dev
