Usage

Each RSL15 device contains trim settings in NVR7, which are calibrated with the nominal settings for the items that the library calibrates. These values are trimmed and flashed for each device during production. The values in NVR7 are accurate enough for most applications that use the nominal settings. The default trim settings can be loaded via the Hardware Abstraction Library macro SYS_TRIM_LOAD_DEFAULT.

These trim settings can be supplemented by additional calibration values. These supplemental values are calibrated using calibration procedures that execute without any external connections, as they utilize the internal analog test bus (AOUT), the crystal oscillators, and the Asynchronous Clock Counter.

IMPORTANT: Before you begin any supplemental calibration, we recommend that you load the default trim settings such that the trim values from NVR7 using SYS_TRIM_LOAD_DEFAULT are loaded, as this puts the system in its nominal state and ensures that critical values, such as the bandgap voltage, are as accurate as reasonably possible. The accuracy of the bandgap is critical for the trimming of regulators and for accurate LSAD measurements.

To use the calibration library functions, include calibrate.h in the application source and in the application link against the libcalibratelib.a library object. For an RTE project, the calibration library can be linked against by selecting Calibrate under Device > Libraries. The calibration library must then be initialized by a call to either Calibrate_Clock_Initialize or Calibrate_Power_Initialize before calling functions from calibrate_clock.c or calibrate_power.c, respectively.

Clock Calibration Notes

The theoretical accuracy of the 32 kHz RC oscillator calibration is correlated with the system clock frequency. As a result, we recommend calibrating while using the RFCLK as the SYSCLK source when calibrating this clock.

The 3 MHz RC oscillator is calibrated relative to the 32768 Hz crystal. If this crystal is not present, this calibration hangs until the watchdog resets the device.

For the complete calibration library API, refer to Supplemental Calibration Library Reference.