Hardware Reference
In-Depth Information
Creating the cape DTS file
Besides the EEPROM, you will also need to create a DTS file. This file defines attributes
of your hardware to the Linux kernel. The DTS file for the CryptoCape Revision 00A0 is
located on GitHub at:
https://github.com/beagleboard/linux/blob/3.8/firmware/capes/BB-
BONE-CRYPTO-00A0.dts
.
When creating a new DTS for your hardware, it's best to re-
view the existing BeagleBone DTS files. With the growing number of capes, there is a
good chance that there exists an approved DTS file with the hardware configuration you
seek.
The BBB device tree overlay system is one of the areas undergoing active development,
and important technical nuances change rapidly. If you need to build your own DTS file,
it's best to check in with the BeagleBoard.org mailing list available at
ht-
Note
A detailed introduction to the device tree system in the Linux kernel was presented by Tho-
mas Petazzoni at the Embedded Linux Conference Europe in November 2013. The present-
ation is available on YouTube at
https://www.youtube.com/watch?v=m_NyYEBxfn8
.
Let's briefly look at a portion of the CryptoCape's DTS file. The
capemgr
will load the
compiled version of this file to configure the hardware. The drivers for some of the chips
on the CryptoCape are also loaded automatically since they are specified in the DTS file, as
shown in the following code:
fragment@2 {
target = <&i2c2>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
/* Real Time Clock */
ds1307@68 {
compatible = "ds1307";
reg = <0x68>;
};
