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leetrieu

[Help] RTC BQ32000

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Hello everybody !!


I tried to calibrtion 1Hz on RTC BQ32000 of TI. 


The calibration process is described below. This calibration process does not works and I would like to know the way in which it should be done correctly. 


 


The steps taken during the calibration procedure were the following:


 


1. Write 0xE0 in the CAL_CFG1 Register during the initialization of the microcontroller . This was done in order to enable the test signal on the IRQ pin of the bq32000.


bit 7 = OUT = 1


bit 6 = FT = 1


bit 5 = S = 1


bit 4, bit 3, bit 2, bit 1, bit 0 = CAL = 00000


 


2. Write 0xFF in the CAL_CFG1 Register. This was done in order to speed the RTC. 


bit 7 = OUT = 1


bit 6 = FT = 1


bit 5 = S = 1


bit 4, bit 3, bit 2, bit 1, bit 0 = CAL = 11111 


This is : CAL(DEC) 31 = -126 ppm.


 


3. Write the key 0x5E in the SF KEY 1 register.


4. Write the key 0xC7 in the SF KEY 2 register.


5. Set the bit FTF (D0) in the SFR Register.  Setting FTF forces the calibration signal to 1Hz, and the calibration tracks the internal ppm adjustment.


6. Read the calibration register CAL_CFG1 Register in order to verify that the bits  4, 3, 2, 1 and 0 = 11111 .


7. Finally, the initial value 10000000b is written to the CAL_CFG1 Register. 


 


The control system continues to be delayed one minute per week, if someone has an idea of something else that could be done please let me know. 


Thanks all. 


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