X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/8e074056acc2ee8edd5222f9937e8c40bfeff013..refs/pull/193/head:/armsrc/util.c?ds=inline diff --git a/armsrc/util.c b/armsrc/util.c index 8576ddce..1dd8dc75 100644 --- a/armsrc/util.c +++ b/armsrc/util.c @@ -304,11 +304,12 @@ void FormatVersionInformation(char *dst, int len, const char *prefix, void *vers void StartTickCount() { -// must be 0x40, but on my cpu - included divider is optimal -// 0x20 - 1 ms / bit -// 0x40 - 2 ms / bit - - AT91C_BASE_RTTC->RTTC_RTMR = AT91C_RTTC_RTTRST + 0x001D; // was 0x003B + // This timer is based on the slow clock. The slow clock frequency is between 22kHz and 40kHz. + // We can determine the actual slow clock frequency by looking at the Main Clock Frequency Register. + uint16_t mainf = AT91C_BASE_PMC->PMC_MCFR & 0xffff; // = 16 * main clock frequency (16MHz) / slow clock frequency + // set RealTimeCounter divider to count at 1kHz: + AT91C_BASE_RTTC->RTTC_RTMR = AT91C_RTTC_RTTRST | ((256000 + (mainf/2)) / mainf); + // note: worst case precision is approx 2.5% } /*