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Re: create file in mmc
There are 32 bytes per directory entry.
The root dir for fat 16 is a range of sectors, starting from the end of the last FAT and has room for BPB_RootEntCnt dir entries.
The start of first FAT sector is the sector where the partion begins + BPB_RsvdSecCnt and one FAT has...
Re: create file in mmc
To create a file > 0 bytes you must
find an un-used cluster
find an un-used directory entry
create a new directory entry
write to the cluster, if more than one cluster in size, find another un-used cluster, and update fat.
close the file with right file size & update fat...
It's not on a PIC and it's not in EEprom, but here is my project for an AVR record & playing from an MMC/SD or CF or harddisk https://mcselec.com/forum/viewtopic.php?t=683
Did you know 33min * 60sec per min = 1980sec at a sample rate of 8k per sec mono = 1980 * 8000 is greater than 15M. If you...
Re: MMC help?
Try sending &HFF just before you lower ss.
If it helps, here is my AVR ASM code.[read_sec]
'***************************************************************
'issue Read Sector command to card
'***************************************************************
'Sub Read_sec(lbasector...
one E1 frame contains 32 timeslots @ 64k each total 2048M
timeslot 0 is used for frame alignment.
timeslot 16 may be used for signalling.
the other timeslots contiain the payload which can voice, or data.
there are many more details.
the bit stream may be RZ or NRZ with a clock, which may be +...
Re: measure current ?
OR
if you don't want to add any extra silicon bits.
Use the Mega 8 A/D converter Differential Input Channel with adjustable Gain of 10x or 200x to measure the AC current straight from the current transformer. (may have to add a bias voltage)
For RMS, just square the...
Because you are addressing data.
You could ask for, or write to sector X.5 to X+1.5. The addressed data does not have to be at a LBA boundary.
If you ask for a an LBA, but the card expects a memory address, you will be out by a factor of 512.
Phil
In order to run open loop, the freq must be ramped up slowly, and hope that the rotor keeps up.
If the rotor does not keep up with the freq of the rotating magnetic field, then the motor will start to buzzzzzz.
Phil
For reading a single block at a time
1 Send the command
Send the read command, then the raw address (LBA *512).
2 Wait for a R1 response
Continue to send 255 till you get something back with bit 7 clear
If <> 0 then error.
3 Wait for token
Continue to send 255 till you get a start token
4 Read...
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