18f452 to 18f4520 migration problem (SPI/SD Card)

Guest · Posted: Sat Apr 05, 2008 5:14 pm

Hi all!

I have a program using SPI to read data from an SD card which works perfectly on a pic18f452. I changed for a 4520 and am now using the internal oscillator with PLL (32Mhz) instead of an external 20Mhz crystal.

I changed the code to initialize the PIC, and the PIC indeed works at the right frequency, but the SD card part is no longer working.

I did not found any informations on the migration documents from microchip relative to SPI.

Does anyone have an idea what could cause this?
Are there things I missed in the migration docs?

Thanks

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Does the SD card work when you select a lower clock frequency? For example the 16MHz with internal oscillator should be easy to check as it requires only a software change.

Guest · Posted: Sun Apr 06, 2008 4:48 am

I tried soldering a 20Mhz crystal and setting config back to what it was originally, but it didn't change anything...

Guest · Posted: Sun Apr 06, 2008 5:56 am

Well finally it works...
It was no software problem, but hardware: There was a junction between one SPI wire and ground because of a small desolder bread wire stuck in....

Thanks for trying to help though!

csuszo · Joined: 01 May 2008 Posts: 1

I'm having troubles to set my intosc on 32MHz can you help me how did you do that?

nicorosen · Joined: 25 Oct 2010 Posts: 2

csuszo, I'm using a PIC18F4520 with internal oscillator @ 32MHz.
All you need is to set the fuses and configure the clock.
This is the code I used and worked well: