I know quite a few of you (myself included) have been waiting for EPEL to support some of the additional architectures like AArch64. We've been working with the EPEL team to try to help this along, but it looks like the earliest this will be available is around late August. Until then, we're producing an unofficial build based on the SRPMs pulled from the fedora/EPEL mirrors. This is meant as a temporary "use at your own risk" set of packages. They are unsigned, and the repository isn't checked for dependency closure. Once the official EPEL repository is available, we will stop maintaining this branch.
If I haven't scared you off yet, you can use this temporary repository by creating an unofficial.repo file in /etc/yum.repos.d with the following contents:
[unofficial-builds] name=CentOS unofficial extra package rebuild baseurl=http://buildlogs.centos.org/c7-epel.a64/ metadata_expire=6h gpgcheck=0 skip_if_unavailable=True
If you find a missing package, or are interested in helping to improve the packages, there's an associated bugzilla at https://bugzilla.redhat.com//show_bug.cgi?id=1285484
Please start there, or discuss/contribute here on the arm-dev@centos.org mailing list.