Roadrunner technical documentation Buy on-line
There are the wirings between the Roadrunner module and a microSD/miniSD or SD card
CPU line | SD Signal | SD Pin # |
---|---|---|
PA0 | CLK | 5 |
PA1 | CMD | 2 |
PA2 | DATA 0 | 7 |
PA3 | DATA 1 | 8 |
PA4 | DATA 2 | 9 |
PA5 | DATA 3 | 1 |
VCC | 4 | |
GND | 3,6 | |
PA13 | CD |
A 68 kOhm pull-up resistor must be wired on each of these lines:
The PA13 line must be wired on CD (Carrier detect) line if your microSD socket has this pin or fixed on GND if not.
This is the device tree definition to use:
ahb {
...
sdmmc0: sdio-host@a0000000 {
bus-width = <4>;
pinctrl-names = "default";
no-1-8-v;
non-removable;
pinctrl-0 = <&pinctrl_sdmmc0_default>;
status = "okay";
};
sdmmc1: sdio-host@b0000000 {
bus-width = <4>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sdmmc1_default>;
};
...
apb {
...
pinctrl_sdmmc0_default: sdmmc0_default {
cmd_data {
pinmux = <PIN_PA1__SDMMC0_CMD>,
<PIN_PA2__SDMMC0_DAT0>,
<PIN_PA3__SDMMC0_DAT1>,
<PIN_PA4__SDMMC0_DAT2>,
<PIN_PA5__SDMMC0_DAT3>;
bias-disable;
};
ck_cd_rstn_vddsel {
pinmux = <PIN_PA0__SDMMC0_CK>,
<PIN_PA13__SDMMC0_CD>;
bias-disable;
};
};
...
};
...
};
To be compatible with boot from MMC0, at91bootstrap must be compiled with these flags configured inside the make menuconfig command (read Compiling AT91bootstrap)
Memory selection --->
Flash Memory Technology (SD card) --->
( ) Dataflash
(X) SD card
and
Memory selection --->
SD Card Configuration --->
SD Host Controller Select (On SDHC0) --->
(X) On SDHC0
( ) On SDHC1