m41t81_read
tm.tm_hour = (tm.tm_hour & 0x3f) | (m41t81_read(M41T81REG_HR) & 0xc0);
sec = m41t81_read(M41T81REG_SC);
min = m41t81_read(M41T81REG_MN);
if (sec == m41t81_read(M41T81REG_SC)) break;
hour = m41t81_read(M41T81REG_HR) & 0x3f;
day = m41t81_read(M41T81REG_DT);
mon = m41t81_read(M41T81REG_MO);
year = m41t81_read(M41T81REG_YR);
tmp = m41t81_read(M41T81REG_SC);
return m41t81_read(M41T81REG_SC) != -1;