„MSP430 MCU” változatai közötti eltérés
| 22. sor: | 22. sor: | ||
Edit: This statement is actually incorrect. Another big thank you goes out to Jens-Michael for pointing it out to me. Thanks for reading! | Edit: This statement is actually incorrect. Another big thank you goes out to Jens-Michael for pointing it out to me. Thanks for reading! | ||
'''"12pF is the typical load for most crystals I've ever seen. But due to the electric connection, a 12pF load means [there will be 2] 24pF capacitance on each of the crystals sides. Reason is that (seen from the crystal), the two capacitors are in series to each other and parallel to the crystal. […] Subtract the ~2pF pin capacitance of the MSPs pins and you get [two separate] 22pF [for] external capacitors, resulting in 12pF load. The XCAP settings already include pin capacitance and the /2 factor."''' | '''"12pF is the typical load for most crystals I've ever seen. But due to the electric connection, a 12pF load means [there will be 2] 24pF capacitance on each of the crystals sides. Reason is that (seen from the crystal), the two capacitors are in series to each other and parallel to the crystal. […] Subtract the ~2pF pin capacitance of the MSPs pins and you get [two separate] 22pF [for] external capacitors, resulting in 12pF load. The XCAP settings already include pin capacitance and the /2 factor."''' | ||
https://www.allaboutcircuits.com/textbook/direct-current/chpt-13/series-and-parallel-capacitors/ | |||
A lap 2017. május 21., 19:41-kori változata
MSP430 MCU family from TI
http://www.ti.com/lit/sg/slab034ad/slab034ad.pdf
MSP430G2553 launchpad
32khz-crystal
Load capacitance !!!
http://www.msp430launchpad.com/2012/03/using-aclk-and-32khz-crystal.html
For example, the LaunchPad uses 12pF capacitors to load the crystal we just installed, yet many crystals require 22pF.
Edit: This statement is actually incorrect. Another big thank you goes out to Jens-Michael for pointing it out to me. Thanks for reading! "12pF is the typical load for most crystals I've ever seen. But due to the electric connection, a 12pF load means [there will be 2] 24pF capacitance on each of the crystals sides. Reason is that (seen from the crystal), the two capacitors are in series to each other and parallel to the crystal. […] Subtract the ~2pF pin capacitance of the MSPs pins and you get [two separate] 22pF [for] external capacitors, resulting in 12pF load. The XCAP settings already include pin capacitance and the /2 factor."
https://www.allaboutcircuits.com/textbook/direct-current/chpt-13/series-and-parallel-capacitors/