SD kart programming using elm chan PetitFat library

[gaugeguy]

The pic18f4431 is not specified to work below 4.2V
If you are powering it from a 3.3V regulator any number of things may intermittently not work.

[Ttelmah]

SD draws a _lot_. Momentarily. The average consumption is not that high, but pulses can be up to 200mA. Most cards less (SanDisk for example specify their cards won't draw more than 100mA). The big problem is the rate of change of consumption. Regulators take time to catch up, and if the consumption changes in a few nSec from almost nothing to perhaps 70mA, this can lead to nasty spikes on the rail. Hence the need to have really good high speed decoupling close to the card.

We are 'harking on this', because the 'no file' error will happen if there is anything less than perfect in the I/O. Given the CCS drivers do work, and are know to work, with the problems you are seeing, it starts to 'smell' that you may well have a hardware issue.

[salih260]

Ttelmah i am used a lot of library for sd card. I read and wrote sd kart sectors. But FAT did not work.
Now I will design a circuit with pic18f. I'll do it by checking step by step. Sleep is forbidden to me without programming the SD card.

* CCS C library, mmcsd.c has run all the functions. But fat.c, fat_init () worked but fatopen () did not work.
* Petit Chan library, diskio.c has worked on all functions. But pff.c, pf_mount () worked but pf_open did not work.

This shows that I have a hardware problem.

What are you thinking?

good work.

[salih260]

[Ttelmah]

The point I'm repeatedly asking, is the say you have read and written sectors, but have you actually _verified_ the read is returning exactly the right data?. Every single bit/byte?. At several locations, and the right data for the location?. This needs to be the step of debugging _before_ you make any attempt to use a FAT library.
Use a hex editor. Dump sector 0, 2, and then a couple higher up the disk. Then read these with your code, and verify the data matches what this shows. Easiest way is to simply output the sectors in hex to serial and you can read this to the PC for comparison.

Debugging needs always to be 'take one step at a time'.

[salih260]

Yeah. I did what you said. For example, in the 5th sector 0x21, 0x54, etc. I've written. Then I read them correctly. If I had not read the sectors and had not written it, pf_mount () would give an error.

What is the name of the hex program for sd card?

[Ttelmah]

Almost any standard hex editor. HxD or WinHex for example.

What are the first three bytes of sector 0?.

These distinguish whether the card has been formatted using a BFB or an MBR.

What does check_fs return?.

I'm thinking of problems, first with handling an MBR, but second with something silly like the raw driver not correctly handling addresses as they get larger. That's why I'd want to check a sector with a much higher address.

[salih260]

Thanks for helping Ttelmah.

check_fs() --> return 0

there is all the data here. Sorry I could not assign a picture here. I gave you a link.

image link: https://drive.google.com/open?id=1W7U7IWFN-VY24m9Pmz2klGNI4P4r_El_

good works.

[asmallri]

[Ttelmah]

I'd add two more things.
With the code as posted in the PetitFat example, he must have:

[salih260]

Thanks asmallri.
I will make your gestures step by step.

[salih260]

Thanks Ttelmah.

I will add these. Let's see what happens this time.

good works.