Yes, I changed it for ttyO0 and now it just shows a black screen. I guess that's kind of better, but still no splash :(
uname_r=3.14.56-ti-r78
##This will work with: Angstrom's 2013.06.20 u-boot.
cmdline = splash
loadaddr=0x82000000
fdtaddr=0x88000000
rdaddr=0x88080000
initrd_high=0xffffffff
fdt_high=0xffffffff
loadximage=load mmc 0:1 ${loadaddr} /boot/vmlinuz-${uname_r}
loadxfdt=load mmc 0:1 ${fdtaddr} /boot/dtbs/${uname_r}/${fdtfile}
loadxrd=load mmc 0:1 ${rdaddr} /boot/initrd.img-${uname_r}; setenv rdsize ${filesize}
loaduEnvtxt=load mmc 0:1 ${loadaddr} /boot/uEnv.txt ; env import -t ${loadaddr} ${filesize};
loadall=run loaduEnvtxt; run loadximage; run loadxfdt;
mmcargs=setenv bootargs console=ttyO0 ${optargs} root=${mmcroot} rootfstype=${mmcrootfstype} ${cmdline}
uenvcmd=run loadall; run mmcargs; bootz ${loadaddr} - ${fdtaddr};
dtb=am335x-boneblack-wl1835mod.dtb
Thanks again