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PIC18F47J53 CCS C Compiler 5.090 mmcsd.c library issue
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Ttelmah



Joined: 11 Mar 2010
Posts: 16338

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PostPosted: Wed Sep 23, 2020 6:44 am     Reply with quote

The downside is if you use an eMMC card these have built in pull-ups,
so you draw more current.....
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Wed Sep 23, 2020 7:27 am     Reply with quote

SCK2 is an output from the PIC, so you are driving it. If you are not using it,
then simply set it as an output, then it is driven. Same applies to all the
pins on the PIC.
Marco27293



Joined: 09 May 2020
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PostPosted: Fri Sep 25, 2020 1:50 am     Reply with quote

Thank you very much :)

Can I use a 680uF electrolytic capacitor as Microsd reservoir ?
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Fri Sep 25, 2020 2:44 am     Reply with quote

Honestly, the HF response, is much more important than the size.
A 22uF multilayer ceramic capacitor, will have much more effect at high
frequencies, than a 10000uF electrolytic....
Understand that traditional electrolytic capacitors are 'great' at a frequency
like 100Hz, but absolutely 'awful' at a frequency like 1MHz. Their actual
effective capacitance reduces as frequency goes up. So a large electrolytic
is a great 'reservoir' to deliver power for things that happen slowly, but
pretty much useless to do the same for things that are happening in a
few nSec, Some types of electrolytic retain HF performance much better.
Capacitors like the Sanyo OSCON, perform perhaps 10* better than a
standard electrolytic. This is the 'point' of having the small ceramic
capacitor adjacent to the electrolytic. This tries to give back some of the
poor HF performance. If you look at a PC motherboard, it will have loads
of electrolytic capacitors in the PSU, but look more carefully, and you will
see literally dozens of small ceramic capacitors. Typically at least one
adjacent to every other IC across the board, often even more. These
are trying to reduce the HF that is otherwise produced by the instantaneous
changes in load produced by every switching operation on the board.
in consumption. Keeping the ripple produced by these changes 'under
control', is absolutely essential for reliability......
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