4.6.1.2 Design Layout Recommendations
When designing the SD Card interface, consider the following recommendations:
- Match signal lengths to within 50 mils. Affected PIOs in the example above are PA0 to PA5.
- Place the clock line (PA0) at least 3 times the trace width away from other signals for noise immunity.
- Apply impedance control of 50 Ohms on the clock and data interfaces.
- Place data signals at least 2 times the trace width away from any other data traces.
- Place data signals at least 1 trace width away from any copper plan.