SHREG_WTCSR_R
wdog_wr_csr(SHREG_WTCSR_R | WTCSR_WT);
wdog_wr_csr(SHREG_WTCSR_R & ~WTCSR_WT);
wdog_wr_csr(SHREG_WTCSR_R | WTCSR_TME); /* start!!! */
wdog_wr_csr(SHREG_WTCSR_R & ~WTCSR_TME); /* stop */
wdog_wr_csr(SHREG_WTCSR_R & ~WTCSR_IOVF); /* clear overflow bit */