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PaxInstruments / labwiz-board

A development board based on the STM32 series processors specifically targeting the STM32F103RxT series.
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Use correct caps on crystals #53

Closed charlespax closed 7 years ago

charlespax commented 7 years ago

Both the 8 MHz and 32.768 kHz crystals use 8 pF caps. Use the right value.

screen shot 2016-09-09 at 12 10 29 screen shot 2016-09-09 at 12 10 19

charlespax commented 7 years ago

8 MHz crystal

C_stray=5
C_load=8
c = 2 × C_load - 2 × C_stray
c = 6 pF

32.768 KHz crystal

C_stray=5
C_load=9
c = 2 × C_load - 2 × C_stray
c = 8 pF

C_stray could be off a bit, so we can just stick with 8 pF on both parts.