12.5.9 Internal High-Frequency Oscillator Frequency Tune

Name: OSCHFTUNE
Offset: 0x09
Reset: 0x00
Property: -

Bit 76543210 
 TUNE[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 

Bits 7:0 – TUNE[7:0] User Frequency Tuning

This bit field controls the manual tuning of the output frequency of the Internal High-Frequency Oscillator (OSCHF). The frequency can be tuned 32 steps down or 31 steps up from the oscillator's target frequency. Thus, the register’s acceptable input value range is -32 to +31.

Writing to bits 6 and 7 has no effect, as bit 5 will be mirrored to bits 6 and 7 due to the 6-bit value in this bit field being represented in a signed (two’s complement) form.

Note: If the Auto-Tune Enable (AUTOTUNE) bit in the Internal High-Frequency Oscillator Control A (CLKCTRL.OSCHFCTRLA) register is enabled, the TUNE value is locked. When AUTOTUNE is disabled, it takes up to 0.75 µs and three Main Clock cycles before this bit field is updated with the latest tune value from the auto-tune operation.