On-Demand Calibration

On-demand calibration is also a sub-feature that can be enabled together with PLL auto calibration and periodic recalibration. This feature allows you to perform calibration whenever you need it, prd_cal_req changes to become a status pin. When prd_cal_req==1, it indicates the timer has expired and goes into calibration soon as shown in Figure 2. To initiate recalibration manually at any time, you need to assert prd_cal_ack and hold prd_cal_ack high until hbc_cal_pass becomes low as shown in Figure 1. Do not deassert prd_cal_ack once you have asserted it.

Figure 1. User Trigger Recalibration on Demand
Figure 2. Timer Trigger Recalibration

The timer reset selection is provided when the on-demand calibration is enabled. When the timer reset is enabled, the timer is reset when you trigger the calibration through prd_cal_ack. Disabling the timer reset prevents the timer from resetting, causing it to continue counting even after you have manually trigger the calibration.