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Author Topic: SD card Interfacing with 8051(P89v51rd2)  (Read 4219 times)
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SANEMB
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« on: September 04, 2012, 08:09:47 08:09 »

i want to interface sd card with p89v51rd2,wat is the hardware interface bz for sd card requires 3.3 v supply but p89v51rd2 has minimum 4.5 v supply is required please suggest.

suggest a circuit diagram

Thanks in advance
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pablo2048
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« Reply #1 on: September 04, 2012, 08:53:10 08:53 »

Use the same schematic as for older AVR CPUs which have same 5V power supply. (If you are too lazy to search internet, use this http://project.irone.org/interface-avr-with-sd-card.html for example...)
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rentau
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« Reply #2 on: September 05, 2012, 05:18:08 17:18 »

you can have level shiftier, to convert 5 to 3 and v.v...

and for SW, this is a good module to use

http://elm-chan.org/fsw/ff/00index_e.html
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wellnerson1
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« Reply #3 on: September 05, 2012, 05:26:17 17:26 »

Dear friend,
See this link may be useful for you.
http://www.dharmanitech.com/
http://www.dharmanitech.com/2011/05/microsd-atmega32-datalogger.html
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Brosske
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« Reply #4 on: September 05, 2012, 05:50:42 17:50 »

Hi all,

Look in the datasheet if the logic '1' level for the p89v51rd2 is detected on 3.3V. Sometimes the chip is compatible...
For the signals that go to the SD-card, I use 10k resistor.

But I agree that level-shifter is more proper way to do it.

greetz.
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solutions
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« Reply #5 on: September 06, 2012, 06:20:33 06:20 »

You should Google before you waste everyone's time asking here. No problem answering questions to help you understand a particular problem, but you should at least make an effort on your own.

See the 1st hit.

http://www.google.com/search?q=8051+sd+card
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flo0319
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« Reply #6 on: October 24, 2012, 11:59:36 23:59 »

Hi, if you want to interface a SD/MMC card with a MCU using SPI bus you need to know that the SPI lines are unidirectional and signal is digital and if your MCU work at 5V you can use 2 simple method for level voltage shift: 1) zenner diode 3v3(or 3v6) between MOSI,SCK,CS line and Ground; 2) resistors (1K - 10K ohms, depends of mcu output current on pin) in series with MOSI,SCK and CS line. Other method like a voltage divider are not so good because after Init a memory card need to work at a high speed and signal wave is change from square in sine (partial, but at a very high speed is a problem with the sample moment).


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