Author Topic: Keysight 1000X scope RTC design error?  (Read 1483 times)

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Offline TKTopic starter

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Keysight 1000X scope RTC design error?
« on: March 28, 2018, 10:53:09 pm »
I was playing with the RTC of my EDUX1002G.  After removing the 32kHz crystal and resoldering it, the scope started to give me Clock HW failure errors, the crystal did not oscillate.  After changing the RTC chip, it continued to give the same error.  After checking the datasheet of the TI BQ32002 RTC chip (The one soldered by Keysight on the PCB), it says that if the crystal matches the load capacitance of 12pF (Which is the most common capacitance of SMD 32kHz crystal), no capacitors are required.  So I desoldered the 2 capacitors and now the scope works without any errors.  Can change the date and it boots back and keeps the correct date and time.

The scope also includes the Sony CR2025 which is a 3V lithium coin cell battery, thinner than the CR2032.  If you remove the battery and reinsert it, most of the time the positive pin holder will not make good contact, giving an error during boot that the scope was reset to factory default settings.  The coin cell battery holder seems to be for the CR2032.

Another oddity I found is that the firmware is writing to RTC registers 0x0C and 0x0F that are not published as valid register addresses on the BQ32002 datasheet. 

« Last Edit: March 28, 2018, 11:04:01 pm by TK »
 
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Offline TKTopic starter

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Re: Keysight 1000X scope RTC design error?
« Reply #1 on: April 07, 2018, 11:58:57 pm »
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