Hardware description: SD interface (self made)

If you don't want to spend money (and support RadioClone project

), you can try to build SD card interface. Unfortunately I can not guarantee that it will always work. Sometimes you need to use other resistors values, or adding additional pull-up resistors to achieve the desired effect.

Parts List

micro SD card adapter
strip header - angular (90 deg)
LD33V - voltage regulator 3.3V (low drop)
3 x 3V3 zener diode
2 x 10K ohm resistor
3 x 1K ohm resistor
2 x 100n F capacitor
universal PCB at least 10 x 10 pads (or better 10 rows)
30 cm network cable (4 pair)
30 cm telephone cable

Schema

At the beginning I must point out, that this scheme strictly experimental. I built three of them, but only 2 works .. I suppose it did not meet the specifications of the voltage and some resistors need to be replaced for larger / smaller.

Board

I used an universal PCB. Black lines indicate GND (ground), orange Vcc 3.3V (power supply)

SD Slot

I used the SD adapter for micro SD. I made the conversion by soldering angular strip header (90 degrees).

Elements Soldering

Next I placed flowing elements

3 x 3V3 zener diode
2 x 10K resistors
1 x 100n F capacitors

like on picture, then solder it (see second picture how). All connection are lined up.

soldering

Soldering SD slot

Place SD slot and rest of the components (like on the picture)

soldering

Wires

Please use that same colours for the cables (further description will then be compatible with your board). Wires of such colors is available from cable and telephone cable.