JAJSMQ2 September 2021 TMAG5170
PRODUCTION DATA
This diagnostic mechanism allows the controller to check any hardware fault with the internal oscillator. With this check, any drift of internal oscillators can be checked. The high-frequency oscillator is critical for precision measurement of the magnetic field and low-power oscillator is critical to control wake-up and sleep mode and other state machine control.
To run this check, external software code on the controller is required. The controller has to instate the check by setting the OSC_CNT_CTL bits to select a particular oscillator and start the internal count on the device. At the same time, the controller should also start a counter using its own timebase. After a pre-determined time, the controller should issue a stop to the oscillator count by setting OSC_CNT_CTL=0x3 and read the OSC_COUNT. The read value of the OSC_COUNT should not exceed the value based off maximum fHFOSC, fLFPOSC in the specification section. Variation of controller clock speed and SPI communication timing need to be considers while calculating the error margin for the OSC_COUNT.
Run Mode | On-demand as run by the external controller |
Data Sheet Parameter(s) | fHFOSC, fLFPOSC |
Configuration Register(s) | OSC_CNT_CTL |
Fault Register Bit | OSC_COUNT |
Impact if disabled | If the controller decides not to run this test, then any drift of HF oscillator can impact the accuracy of the reported sensor data |