Dear all, I would like to make a board to connect to the BBB in such a way to have an SD card connected to the BBB by the mmc2 bus. In this way could have 2 SD card accessible by the ARM. I am not pretty sure if it is possible (in principle it could be).
I need your help in setting the software part. In particular, this is how I would set the .dts file /* * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ /dts-v1/; /plugin/; / { compatible = "ti,beaglebone-black"; ti,on-baseboard; /* identification */ part-number = "BB-MMC2-01"; /* mmc2*/ version = "00A0"; /* revision 0*/ fragment@0 { target = <&am33xx_pinmux>; __overlay__ { emmc3_pins: pinmux_emmc3_pins { pinctrl-single,pins = < 0x8c 0x33 /* mmc2_clk, INPUT_PULLUP | MODE3 */ 0x88 0x33 /* mmc2_cmd, INPUT_PULLUP | MODE3 */ 0x44 0x33 /* mmc2_dat0, INPUT_PULLUP | MODE3 */ 0x48 0x33 /* mmc2_dat1, INPUT_PULLUP | MODE3 */ 0x4c 0x33 /* mmc2_dat2, INPUT_PULLUP | MODE3 */ 0x78 0x33 /* mmc2_dat3, INPUT_PULLUP | MODE3 */ 0x74 0x34 /* mmc2_cd, INPUT_PULLUP | MODE4 */ 0x184 0x31 /* mmc2_wp, INPUT_PULLUP | MODE1 */ >; }; }; }; fragment@1 { target = <&mmc3>; /* actual mmc2 */ __overlay__ { pinctrl-names = "default"; pinctrl-0 = <&emmc3_pins>; vmmc-supply = <&ldo3_reg>; bus-width = <4>; ti,non-removable; status = "okay"; }; }; }; I am already using pins P8.11 -> P8.17 and P8.19 : that's why I am not using those pins. It is not fully clear what "bus-width = <4>" is : is it the data-bus (dat0 dat1 dat2 dat3)? or the full signals bus (data + cmd + clk)? Reading around this forum, it looks like the "native" SD card of the BBB has to be plugged before to switch on the BBB. I guess it is the same for the new SD card I want to add. It means that I have to modify the uEnv.txt file because it has to be asserted immediately that I'll use the mmc2 bus. What I would add in the uEnv.txt file is something like: capemgr.enable_partno=BB-MMC2-01 but it is not fully clear to me where I have to add it. This is my uEnv.txt file (I am using debian, not an Angstrom Distribution): kernel_file=zImage initrd_file=uInitrd initrd_high=0xffffffff fdt_high=0xffffffff #Video: Uncomment to override: #kms_force_mode=video=HDMI-A-1:1024x768@60 ##BeagleBone Cape Overrides ##Note: On the BeagleBone Black, there is also an uEnv.txt in the eMMC, so if these changes do not seem to be makeing a difference... ##BeagleBone Black: ##Disable HDMI/eMMC optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G console=ttyO0,115200n8 mmcroot=/dev/mmcblk0p2 ro mmcrootfstype=ext4 rootwait fixrtc loadkernel=load mmc ${mmcdev}:${mmcpart} 0x80200000 ${kernel_file} loadinitrd=load mmc ${mmcdev}:${mmcpart} 0x81000000 ${initrd_file}; setenv initrd_size ${filesize} loadfdt=load mmc ${mmcdev}:${mmcpart} 0x815f0000 /dtbs/${fdtfile} boot_classic=run loadkernel; run loadinitrd boot_ftd=run loadkernel; run loadinitrd; run loadfdt device_args=run expansion_args; run mmcargs mmcargs=setenv bootargs console=${console} ${optargs0} ${optargs} ${kms_force_mode} root=${mmcroot} rootfstype=${mmcrootfstype} ${expansion} expansion_args=setenv expansion ip=${ip_method} #Classic Board File Boot: #uenvcmd=run boot_classic; run device_args; bootz 0x80200000 0x81000000:${initrd_size} #New Device Tree Boot: uenvcmd=run boot_ftd; run device_args; bootz 0x80200000 0x81000000:${initrd_size} 0x815f0000 Finally, from the "hardware" point of view, I'm planning to copy the schematics of the BBB to set the pull-up resistors. At the end, I guess that the SD card will be automatically recognized when the BBB is powered up (all drivers should be already written)....right? Could you help me in setting the software part? Is there something important that I am missing (in the software/hardware part)? Regards. Alberto -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
