13.3 SDMMC I/O calibration does not work

The impedance calibration mechanism for the SDMMC I/Os does not work. A fixed calibration code is internally hard-wired and, as a result, the calibration procedure described in the device data sheet, section “ I/O Calibration”, has no effect.

The I/O impedance values are given in the section "Electrical Characteristics" of the data sheet.

With these values and careful PCB design (impedance controlled and matched traces), the SDMMC can be operated in HS200 and in SDR104 modes up to 120 MHz .

Work around

None