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Beaglebone mikroBUS Cape


The mikroBUS Cape is an expansion board for the BeagleBone that allows users to connect up to 4 mikroElektronika Click boards to the BeagleBone without any wiring.

Software Support & Compatibility

No software support is required by this board. All revisions are compatible with BeagleBone and BeagleBone Black.

Examples are compatible with BeagleBone and BeagleBone Black.

NOTE: At this point in time the Debian kernel is experiencing issues with applying device tree overlays, the examples may not work.

Getting Started

BeagleBone (White)

To allow BB to identify appropriate pin headers configuration, Click Cape have an onboard EEPROM programmed to make the use of the Cape “plug and play”, just insert the Cape and reboot the BB.

BeagleBone Black

From adoption of Linux kernel 3.x a new method to configure pin headers was introduced, at the boot time an in-kernel utility named “capemgr” dynamically load Device Tree definitions to configure an appropriate pin headers and bus initialization.

As in the case of the White, reading the information stored in the onboard EEPROM, the use of Click Cape is “plug and play” but needs that the user (just one time) put the *.dtbo file (downloadable form git or from our server) in /lib/firmware and reboot the system.

Before this setup it is strongly suggested to start with a fresh install of the OS, latest images are found here: Latest images It is also recommended to try a fresh install to make sure that the system has no user caused errors, or leftovers from previous projects.

Angström setup
$ git clone git://
$ cd BBB-mikroBUS-Cape
$ mkdir bbclickdtbo
$ tar -C /home/root/BBB-mikroBUS-Cape/bbclickdtbo/ -xvf BB_board_dtbo.tar
$ cd bbclickdtbo/
$ cp BB-MIKROBUS-01-00A1.dts /lib/firmware/
$ cp BB-MIKROBUS-01-00A1.dtbo /lib/firmware/
$ reboot
Debian setup

NOTE: At this time due to the changes being made in the kernel, the Device Tree Overlay is not functional. The Linux comminity is currently working on the Device Tree handling.

$ git clone git://
$ cd BBB-mikroBUS-Cape
$ mkdir bbclickdtbo
$ tar -C  /root/BBB-mikroBUS-Cape/bbclickdtbo/  -xvf BB_board_dtbo.tar
$ cd bbclickdtbo/
$ cp BB-MIKROBUS-01-00A1.dts /lib/firmware/
$ cp BB-MIKROBUS-01-00A1.dtbo /lib/firmware/
$ reboot

HDMI Disable

For the BeagleBone Black to function properly wit the cape the HDMI has to be disabled. To do this you have to replace the contents of the uEnv.txt file in the FAT partition of the BeagleBone Black:

$ mkdir /mnt/boot
$ mount /dev/mmcbk0p1 /mnt/boot
$ nano /mnt/boot/uEnv.txt

Replace the contents of uEnv.txt to this

optargs=quiet capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

Then save and exit (Control+X, then Y then Enter), and reboot.

On debian this can be done by uncommenting the same line in the uEnv.txt

For terminal access through the debug port of the BeagleBone it is recommended to use PuTTY which can be downloaded here: PuTTY

For SD card imaging use Win32 Disk imager which is available from here: Win32 Disk Imager

Make your life easier

Make a .profile file in your root to make your life a lot easier when working with DT. Using the export command you can route the $PINS and $SLOTS, this allows you to easily see the pin statuses by using the 'cat $PINS' or 'cat $SLOTS' command. By adding this into a .profiles file these mappings are applied every time you start your board.

$ nano .profile

Then add the text below to it for Angström

export SLOTS=/sys/devices/bone_capemgr.8/slots
export PINS=/sys/kernel/debug/pinctrl/44e10800.pinmux/pins

Use this for Debian

export SLOTS=/sys/devices/bone_capemgr.9/slots
export PINS=/sys/kernel/debug/pinctrl/44e10800.pinmux/pins

Then save and exit (Control+X, then Y then Enter)

Use Github

All files and documents that are nessecary to get the Cape working is also availible on github. To use our github repositories do the following:

$ git clone git://

RTC2 Click

As the RTC2 Click is connected via I²C it can be connected to any port on the cape. With the default dtbo file in place it will certainly work without any programming. All you have to do is to set the date and time first

$ date -s 2014.07.24-15:00

Then write it to the RTC2 by

$ hwclock -w

As long as you have a good battery the correct time should be kept by the device after recovering from a power loss or a restart.


Signal Usage

Click Host 1

Click Pin BBB Pin Signal Mode $PINS ADDR/ OFFSET GPIO NO.
ANP9.38 (default)
P8.26 (optional)
AIN3 (default)
GPIO1_29 (optional)
- - -
RST P9.12 GPIO1_28 7 30 0x878/078 60
CS P9.28 SPI1_CS0 3 103 0x99c/19c 113
SCKP9.31 SPI1_SCLK 3 100 0x990/190 110
MISOP9.29 SPI1_D0 3 101 0x994/194 111
MOSIP9.30 SPI1_D1 3 102 0x998/198 112
+3.3VP9.3 - P9.4VDD_3V3EXP- - - -
GND P9.43 - P9.46 GND - - - -
PWM P9.14 EHRPWM1A 6 18 0x848/048 50
INT P9.15 GPIO1_16 7 16 0x840/040 48
RX P9.21 UART2_TXD 1 85 0x954/154 3
TX P9.22 UART2_RXD 1 84 0x950/150 2
SCL P9.19 I2C2_SCL 3 95 0x97c/17c 13
SDA P9.20 I2C2_SDA 3 94 0x978/178 12
+5V NC - - - - -
GND P9.43 - P9.46 GND - - - -

Click Host 2

Click Pin BBB Pin Signal Mode $PINS ADDR/ OFFSET GPIO NO.
AN P9.37 (default)
P8.15 (optional)
AIN2 (default)
GPIO1_15 (optional)
- - -
RST P9.23 GPIO1_17 7 17 0x844/044 49
CS P9.42 SPI1_CS1 2 89 0x964/1a0 7
SCK P9.31 SPI1_SCLK 3 100 0x990/190 110
MISO P9.29 SPI1_D0 3 101 0x994/194 111
MOSI P9.30 SPI1_D1 3 102 0x998/198 112
+3.3V P9.3 - P9.4 VDD_3V3EXP - - - -
GND P9.43 - P9.46 GND - - - -
PWM P9.16 EHRPWM1B 6 19 0x84c/04c 51
INT P9.41 GPIO0_207 - 0x9a8/1a8 116
RX NC - - - - -
TX NC - - - - -
SCL P9.19 I2C2_SCL 3 95 0x97c/17c 13
SDA P9.20 I2C2_SDA 3 94 0x978/178 12
+5V NC - - - - -

Click Host 3

Click Pin BBB Pin Signal Mode $PINS ADDR/ OFFSET GPIO NO.
AN P9.40 (default)
P8.12 (optional)
AIN1 (default)
GPIO1_12 (optional)
- - -
RST P8.14 GPIO0_26 7 10 0x828/028 26
CS NC - - - - -
SCK NC - - - - -
MISO NC - - - - -
MOSI NC - - - - -
+3.3V P9.3 - P9.4 VDD_3V3EXP - - - -
GND P9.43 - P9.46 GND - - - -
PWM P8.19 EHRPWM2A 4 8 0x820/020 22
INT P8.18 GPIO2_1 7 35 0x88c/08c 65
RX P9.24 UART1_TXD 0 97 0x984/184 15
TX P9.26 UART1_RXD 0 96 0x980/189 14
SCL P9.19 I2C2_SCL 3 95 0x97c/17c 13
SDA P9.20 I2C2_SDA 3 94 0x978/178 12
+5V NC - - - - -
GND P9.43 - P9.46 GND - - - -

Click Host 4

Click Pin BBB Pin Signal Mode $PINS ADDR/ OFFSET GPIO NO.
AN P9.39 (default)
P8.11 (optional)
AIN0 (default)
GPIO1_13 (optional)
- - -
RST P8.16 GPIO1_14 7 14 0x838/038 46
CS NC - - - - -
SCK NC -- - - -
MISO NC - - - - -
MOSI NC - - - - -
+3.3V P9.3 - P9.4 VDD_3V3EXP - - - -
GND P9.43 - P9.46 GND - - - - -
PWM P8.13 EHRPWM2B 4 9 0x824/024 23
INT P8.17 GPIO0_27 7 11 0x82c/02c 27
RX P9.13 UART4_TXD 6 29 0x874/074 31
TX P9.11 UART4_RXD 6 28 0x879/070 30
SCL P9.19 I2C2_SCL 3 95 0x97c/17c 13
SDA P9.20 I2C2_SDA 3 94 0x978/178 12
+5V NC - - - - - -
GND P9.43 - P9.46 GND - - - -

Analog Pin note - Solder Jumpers

Each “AN” Click pin by default is connected to the analog pin of the BBB, if you want to use these “AN” pin as a digital pin you must to cut the wire in the jumper in the bottom of the Cape and solder it as needed.

+5 Volt Enable

To use clickboards that require 5 volts you must solder the 5V enable contact at the bottom. WARNING: Be careful, the ARM processor is only 3.3V tolerant, giving 5v to any input will result in a broken pin or even a broken ARM chip making the board nonfunctional.


The dip-switch “ADDR” in the bottom of the Cape allow user to modify I2C address of the EEPROM, this is useful in case of conflict or cascade of Capes. The two pin represent the last two bits of the address so the allowable address range is composed of four address, from 0x54 to 0x57 (default 0x57).

EEPROM Support No
Board NameBeagleBone mikrobus Cape
Part NumberTIG-02413
Pins Used0


Data stored in the EEPROM is a simple structure formatted in JSON ( which describes Cape and pin configuration needed, for a complete discussion see the BBB Reference Manual.

Here you can download the original JSON file we used to program Click Cape. Starting from there the user can create his custom EEPROM data structure.

With the command line routine “eeprom.js” we can parse JSON file and create the binary file who is write in the memory.

First create a symbolic link in the home to facilitate the work

$ cd
$ ln -s /usr/lib/node_modules/bonescript/eeprom.js eeprom.js

Write the binary file

$ node eeprom.js –w clickcape.json

Check the binary file

$ hexdump –C clickcape.eeprom

Write data in the EEPROM

$ cat clickcape.eeprom > /sys/bus/i2c/drivers/at24/1-0057/eeprom

Note: 1-0057 means I2C bus number 1 and address 0x57.

Reboot the system.

For more information see chapter 7 of the BeagleBone System Reference Manual

Custom DTS

For each different pin configuration a new DTS file needs to be configured, so if you would like to use a configuration that differs from the standard configuration then you need to build your own configuration. On github there is a documentation for what the standard pins and values are for and what default mode they are in.

At boot an in-kernel utility “capemgr” check the records “partNumber” and “version” in the EEPROM header and load DT according the file name from directory /lib/firmware.

If you want a custom pin configuration you must edit DT Source file (.dts), compile it and copy in the directory.

To use any of the build files from the git you will need to change its permissons using the “chmod 777 build” command.

$ dtc -O dtb -o BB-MIKROBUS-01-00A1.dtbo -b 0 -@ BB-MIKROBUS-01-00A1.dts
$ cp /lib/firmware/BB-MIKROBUS-01-00A1.dtbo /lib/firmware/BB-MIKROBUS-01-00A1.dtbo.bak
$ cp BB-MIKROBUS-01-00A1.dtbo /lib/firmware/BB-MIKROBUS-01-00A1.dtbo

Then reboot.

Check if DT is already loaded on Angström by typing

$ cat /sys/devices/bone_capemgr.8/slots

To check on Debian there is only one number difference

$ cat /sys/devices/bone_capemgr.9/slots

If you added the recommended settings in the .profile file then you can just type

$ cat $SLOTS

Here you can download the original DTS file. Starting from there the user can create his custom Device Tree definitions.

Note: you can load a DT definitions without reboot on Angström with

$ echo BB-MIKROBUS-01:00A1 > /sys/devices/bone_capemgr.8/slots

On debian

$ echo BB-MIKROBUS-01:00A1 > /sys/devices/bone_capemgr.9/slots

After this you can check again if the cape has been loaded.

$ cat $SLOTS

If you have left the PWM checks in the DT files then you should see the PWM pins being checked. If there is a module connected that is not using PWM the PPWM check will fail, but otherwise all tests should be successful.

For more information see and

Accessing pins directly

Once you have correctly built a dtbo file and successfully loaded the firmware with no errors, you can directly access the gpios. To do this you will have to find the PIN number and export it. Lets export the PWM pin that switches RL1 on the mikrobus relay click board.

$ cd /sys/class/gpio
$ echo 50 > export
$ cd gpio50

Within that folder the folders are what you can echo and set a value for, and see the status by cat-ing the value. For example lets set gpio50 direction to out so that the relay can function.

$ echo "out" > direction

To turn on the relay just set the value in a similar fashion

$ echo 1 > value

After you are done you need to unexport the GPIO

$ echo 50 > unexport



Jump right into the Examples we have.

Note: We are working on libraries/examples for all available and upcoming click boards. Please see the list of currently supported clicks. Beaglebone supported Clicks Also note that these example are working on Ängstrom OS with kernel version 3.8, it has not yet been verified for any other OS es such as Debian.

Before you can start with our examples proceed the following steps to allow for python applications to run:

$ opkg update
$ opkg install python-dev python-distutils python-smbus python-pip python-setuptools
$ reboot
// Go into the git clone folder
$ cd /home/root/BBB-mikroBUS-Cape/Examples
// Install spidev
$ cd py-spidev/
$ python install
$ cd ..

After you have installed the spidev you are ready try our examples. The examples can be found in the examples folder of the git folder.

If you want to try a python example then use this format to run

 $ python

If you want to run a C or C++ program just run the compiled program

 $ ./example_name

Some examples require the swapping of the .dtbo file in the /lib/firmware folder. This process is explained in the custom DTS section.

Click specifics

A few of the Click boards need specific packages to be installed for them to function properly.

CAN SPI click

To make the CAN click examples work you have to install the can-utils which is equipped with mcp2515 driver, also the default dtbo file is suggested. To do this perform the following actions

$ cd /BBB-mikroBUS-Cape/Examples/CAN-click
$ mkdir can-utils
$ tar  -C /BBB-mikroBUS-Cape/Examples/CAN-click/can-utils -xvf can-utils.tar
$ cd can-utils/
$ make 
$ make install

After this you can Power on the CAN bus (these settings are only example settings, they can be set at any point withing the CAN bus spec)

$ ip link set can0 type can bitrate 125000 triple-sampling on
$ ifconfig can0 up

After this you can use the can-utils commands to send and receive data through the CAN bus.

RS485 click

This click uses UART so if plugged into Host 3 they are directly compatible with most of the RS485 exaples on the web as the RxD and Txd pins on the beaglebone are uart1.

RS232 click

RS232 click uses a UART communication, so just like the RS485 click the RxD and TxD pins are connected to the uart1 of the beaglebone.

RTC2 click

This click uses I²C this makes it directly able to be communicated with, using the default dtbo configurations.

Programming examples



To access SPI through python fist define and import spidev

import spidev

Open SPI

spi = spidev.SpiDev(),0) 

To write to SPI use

spi.writebytes(  )

To tranfer using SPI use the (this is the command you need to use to transfer (j,i though SPI to multiplexers, like the LED Click and the Expand click)

spi.xfer(  )

Bytes can be read as well by


At the end of the program SPI needs to be close to do this just type


As with any program import I²C class. The should be in the same folder for this to work.

import I2C

Look for I²C devices

i2cdetect -y -r 0
i2cdetect -y -r 1

Where to buy


tigalcapes/bb_mikrobus_cape.txt · Last modified: 04/09/2014 15:00 by tiziano