22.4.3.6 Calibration Bit

Calibration bits do not interfere with the embedded Flash memory plane.

The calibration bits cannot be modified.

The status of calibration bits are returned by the EEFC. The sequence is as follows:

  1. Execute the ‘Get CALIB Bit’ command by writing EEFC_FCR.FCMD with the GCALB command. Field EEFC_FCR.FARG is meaningless.
  2. Calibration bits can be read by the software application in EEFC_FRR. The first word read corresponds to the first 32 calibration bits. The following reads provide the next 32 calibration bits as long as it is meaningful. Extra reads to EEFC_FRR return 0.

The 8/12 MHz internal RC oscillator is calibrated in production. This calibration can be read through the GCALB command. Table 22-4 shows the bit implementation.

The RC calibration for the 4 MHz is set to ‘1000000’.

Table 22-4. Calibration Bit Indexes
Description EEFC_FRR Bits
8 MHz RC calibration output [28–22]
12 MHz RC calibration output [38–32]