The goal of this article is to run a C program bare metal on an ARM Cortex M3. We will go through the assembler code generated from a small program written in C and come up with the prerequisites that must be in place in order for it to run.

s I plan to move from a proprietary calendaring to a more „ressource-aware” open source solution, I decided to give Radicale a try. It is open source, appears to be rather pragmatic in its approach to „standards” and has a small footprint in regards to system requirements.

With me running Debian 8 on my server, I decided to stick with the available package and not install „from source”. So a quick „apt-get install radicale” took care of installing the necessary software (do not forget to enable the Radicale daemon in /etc/default/radicale).

The configuration of Radicale is rather straightforward and simple. In regards to transport security, You can reuse an existing TLS certificate (or get a new one from Let’s encrypt). For authentication, you can choose between several options. As I don’t have an LDAP server (yet) and I didn’t want to create a .httpasswd entry for each user, I chose „IMAP”. So Radicale will validate all credentials against the local IMAP server (Dovecot in my case).