The SDMMC_CLKCR register controls the SDMMC_CK output clock, the SDMMC_RX_CLK receive clock, and the bus width.
| CLKDIV | Clock divide factor This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0). This field defines the divide factor between the input clock (SDMMCCLK) and the output clock (SDMMC_CK): SDMMC_CK frequency = SDMMCCLK / [2 * CLKDIV]. 0xx: etc… xxx: etc… |
| PWRSAV | Power saving configuration bit This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) For power saving, the SDMMC_CK clock output can be disabled when the bus is idle by setting PWRSAV: |
| WIDBUS | Wide bus mode enable bit This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) |
| NEGEDGE | SDMMC_CK dephasing selection bit for data and Command. This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0). When clock division = 1 (CLKDIV = 0), this bit has no effect. Data and Command change on SDMMC_CK falling edge. When clock division >1 (CLKDIV > 0) & DDR = 0: - SDMMC_CK edge occurs on SDMMCCLK rising edge. When clock division >1 (CLKDIV > 0) & DDR = 1: - Data changed on the SDMMCCLK falling edge succeeding a SDMMC_CK edge. - SDMMC_CK edge occurs on SDMMCCLK rising edge. - Data changed on the SDMMC_CK falling edge succeeding a SDMMC_CK edge. - SDMMC_CK edge occurs on SDMMCCLK rising edge. |
| HWFC_EN | Hardware flow control enable This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) When Hardware flow control is enabled, the meaning of the TXFIFOE and RXFIFOF flags change, please see SDMMC status register definition in Section56.8.11. |
| DDR | Data rate signaling selection This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) DDR rate shall only be selected with 4-bit or 8-bit wide bus mode. (WIDBUS > 00). DDR = 1 has no effect when WIDBUS = 00 (1-bit wide bus). DDR rate shall only be selected with clock division >1. (CLKDIV > 0) |
| BUSSPEED | Bus speed mode selection between DS, HS, SDR12, SDR25 and SDR50, DDR50, SDR104. This bit can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) |
| SELCLKRX | Receive clock selection. These bits can only be written when the CPSM and DPSM are not active (CPSMACT = 0 and DPSMACT = 0) |