MikroElektronika의 MikroBUS™ Standard Specifications 규격서

mikro BUS
June, 2015
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mikroBUSstandard specifications
Revision history:
Revision Number: Revision Date: Summary of changes: Authors:
2.00 May, 2015 Thorough revision and redefinition of the standard
to encompass add-on boards and sockets. A.N., S.T., S.M., R.M.
1.00 August, 2011 Initial mikroBUS standard, introducing the
pinout and the add-on board concept. A.N.
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mikroBUSstandard specifications
Index Revision history 2
Index 3
Introduction 4
mikroBUS socket standard 5
Pinout specification 6
Silkscreen markings 7
Placement requirements 9
mikroBUS add-on board standard 10
Pinout specification 11
Silkscreen markings 12
Add-on board size and shape 12
Appendix 13
Placement recommendations 14
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mikroBUSstandard specifications
The mikroBUS standard defines mainboard sockets and add-on
boards used for interfacing microcontrollers or microprocessors
(mainboards) with integrated circuits and modules (add-on
The standard specifies the physical layout of the mikroBUS
pinout, the communication and power supply pins used, the
size and shape of the add-on boards, the positioning of the
mikroBUS socket on the mainboard, and finally, the silkscreen
marking conventions for both the add-on boards and sockets.
The purpose of mikroBUS is to enable easy hardware
expandability with a large number of standardized compact
add-on boards, each one carrying a single sensor, transceiver,
display, encoder, motor driver, connection port, or any other
electronic module or integrated circuit.
Created by MikroElektronika, mikroBUS is an open standard —
anyone can implement mikroBUS in their hardware design, as
long as the requirements set by this document are being met.
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mikroBUSstandard specifications
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mikroBUSstandard specifications
The mikroBUS socket comprises a pair of 1x8 female headers with a proprietary pin
configuration and silkscreen markings. The pinout (always laid out in the same order)
consists of three groups of communications pins (SPI, UART and I2C), six additional pins
(PWM, Interrupt, Analog input, Reset and Chip select), and two power groups (+3.3V and GND on
the left, and 5V and GND on the right 1x8 header). The spacing of pins is compatible with standard
(100 mil pitch) breadboards.
Pin functions/silkscreen markings for the socket (see page 11 for how to mark add-on boards)
The following pages contain detailed specification on how to implement mikroBUS sockets into your hardware design. The
easiest way to ensure that your design is in accordance with the prescribed standards, is to use our Altium Designer template
files. Download them from:
Analog - AN
Reset - RST
SPI Chip Select - CS
SPI Clock - SCK
SPI Master Input Slave Output - MISO
SPI Master Output Slave Input - MOSI
VCC-3.3V power - +3.3V
Reference Ground - GND
PWM - PWM output
INT - Hardware Interrupt
RX - UART Receive
TX - UART Transmit
SCL - I2C Clock
SDA - I2C Data
+5V - VCC-5V power
GND - Reference Ground
Pinout specification
mikroBUS socket standard
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mikroBUSstandard specifications mikroBUS socket standard
Silkscreen markings
1. mikroBUS logo positioned above the socket
2. Pin names corresponding to the mikroBUS standard
3. Pin names corresponding to the routing of the mainboard
4. A line that encloses the socket on all sides except the top, as shown above
5. Socket number, necessary only when multiple sockets are on the same board.
6. A diagonal notch below the right-hand side pinout (serves as a guideline for
add-on board insertion)
The full mikroBUS silkscreen
markings also include the print on
the backside of the board. While the
front of the board often contains
a lot of components making it
difficult to retain the full markings,
the backside rarely has such
constraints. Therefore, even when
deviating from the full silkscreen
markings (see next page),
designers are required to retain the
markings on the backside.
Full mikroBUS silkscreen markings
Rear viewFront view
To preserve the integrity of the mikroBUS standard, it’s important to always include the mikroBUS
logo and the default mikroBUS pin names on the silkscreen markings. It is preferable to retain
the full mikroBUS silkscreen markings, but a few alternatives are also permitted.
I] AN/RAZ RCO/PWM I] nnnnnnnn E E :I E — RST/RE1 RBO/INT g _ I E 3 E I CS/RED RC7/RX 3 mlkro 9 E 3' Z . Y BUS ”' E 3 § 0 SCK/RC3 ROS/TX 3 g E :1 _ x MISC/RC4 Rea/50L g g |: 3 j . Musw/Rcs RC4/SDA v. f E j E . «aav +5v 3 i uuuuuuuu 3. GND GND 2 1 % |:| I I Z . mikr‘o 5 El 5 BUS ‘3 ‘3 '3 7 mikro mikro mikro BUS BUS BUS El AN PWM |:| 3 nnnnnnnn D AN PWM U P RST \NT ”' E :1 RST INT |:| f E J x |:| cs |:| RX 1 E j 5 cs |:| RX SCK TX 5 E J 5 SCK TX " E j 7 Mlso SCL ‘3 c :1 2 M‘SO SCL mosx SDA a uuuuuuuu é MOSI SDA +3 3V +5V i E +3 3v +5v GND GND 3 3 GND GND
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mikroBUSstandard specifications mikroBUS socket standard
Printed vertically. In this case, MOSI
turns into SDO and MISO turns into SDI.
Alternative front markings positioning
2) Pin markings 3) Silkscreen outline
It’s not always possible to retain the full silkscreen markings (either because the space between the pins is populated with other
components, or the socket is near the edge of the board). In those cases, designers should follow these guidelines.
Shortened to include only the
default pin names of the mikroBUS
To save space, pin markings can be: The silkscreen outline can also be
left out...
...but the bottom right notch should
be preserved because it ensures
proper add-on board insertion.
- A - - B -
1) mikroBUS logo
Anywhere in the space between
the pins (requires pin names to be
printed out vertically)
In the bottom position without the mikroBUS type —
however, the full logo must still be
present on the backside of the board.
When the logo can’t be printed in the default top position, it can be placed:
- A - - B - - C -
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mikroBUSstandard specifications mikroBUS socket standard
2 5
Placement requirements
Dimensions In-line placement
Socket numbering
The mikroBUS silkscreen markings should be oriented upright relative
to the socket — not the entire board. Thus, in the bottom to bottom
placement, the socket number and other markings are written out
opposite to each other.
Multiple sockets in two rows should be
enumerated in clockwise direction.
1 2
3 4
A mainboard can contain one or more mikroBUS sockets. More sockets allow more add-on boards and
the number of possible add-on board combinations grows exponentially. The upper limit is imposed by
the I/O on the mainboard microcontroller (such considerations are beyond the scope of this standard
and are subject to good engineering practises). Adhere to these guidelines when placing sockets:
Bottom-to-bottom placement
mikro BUS @mkroilektrunlla
mikroBUSstandard specifications
Add-on board
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mikroBUSstandard specifications mikroBUS add-on board standard
The large number of mutually compatible mikroBUS add-on boards is the key value of
this standard. Each one carries a single IC or module that brings a specific functionality
to a target mainboard. New add-on boards enhance the existing range and provide more
choice to end-users. To simplify their use and standardize their appearance, when creating
mikroBUS add-on boards, designers should adhere to a few requirements in regard to the size,
layout and silkscreen markings.
1. When a module uses an interface
already featured on mikroBUS, use
those exact pins and mark them
accordingly. This is the default layout:
2. When a pin is not used, it
should be marked NC (for
Not Connected)
3. When there’s no overlap be-
tween the name or function
of a given mikroBUS pin
and the pin on the module,
the silkscreen should spell
the name of the pin from
the module. (In this exam-
ple, DEF is in place of the
default AN pin.)
4. Some add-on boards can
have a separate pinout in
addition to mikroBUS.
These are usually marked
by their function, here GPIO.
The pinout on a mikroBUS add-on board corresponds with the module, not the target mainboard.
As such, some pins are left unused and some deviate from the default configuration as seen on
the mikroBUS socket. Four cases should be considered.
Pinout specification
boards TX RX SDO SDI
Note the differences: UART markings
are criss-crossed because receivers
are matched to transmiters. SPI
markings are abbreviated. Like so:
Example add-on board
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mikroBUSstandard specifications mikroBUS add-on board standard
Board thickness
h = 1.6 mm
Hole diametar
ø 35 mils
board name
board name
board name
Three sizes are prescribed for mikroBUS add-on boards: S, M and L. When designing yours, use the smallest size sufficient to hold a
given module. Sensors and transceiver chips will fit on S or M in most cases. Odd-shaped encoders or larger connectors will require an
L. Whichever size you use, make sure to retain the notch on the bottom right corner of the board (serves as a guide for proper insertion
into the socket). Otherwise, you are free to experiment with the shape of the board as long as its confined into these dimensions.
Add-on board size and shape
1. The add-on board’s name on the
bottom of the board (front side)
2. Individual pin markings, refer to the
pinout section on the previous page
3. Pin markings on the front always
printed vertically, to conserve space.
4. Pin markings on the backside of the
board printed horizontally, for clarity
5. mikroBUS logo anywhere on the
board (either front or back)
6. If space permits, it is good practice
to label individual components on the
add-on boards (different LEDs, SMD
jumpers and similar).
7. If applicable, indicate RoHS, CE, WEE
and similar compliance with proper
8. Include an icon to indicate power
supply (3,3V, 5V, or both)
click boards are MikroElektronika’s brand of mikroBUS add-on boards. The click
board name is MikroElektronika’s trademark. Third party developers are not allowed
to call their own mikroBUS add-on boards click boards, nor use the word “click” on
the silkscreen. To learn more about click boards visit www.mikroe.com/click
Silkscreen markings
6 8
click boards
Required: Optional:
Front view Back view
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mikroBUSstandard specifications
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mikroBUSstandard specifications Appendix
Placement recommendations
mikroBUS add-on boards extend
beyond the socket. Placing the socket
near tall components like screw
terminals, Ethernet ports etc. could
pose a barrier to add-on boards.
If you plan to enclose the mainboard
in a casing, place the sockets so that
M and L-sized add-on boards can't
portrude beyond the edge of the board.
On the other hand, keep in mind that add-
on boards have various sensors that can
work only under proper conditions. For
example, sensors intended to measure
ambient temperature shouldn't be
placed near heat sinks, UV sensors
have to be exposed and so on. Evaluate
the application of your mainboard and
implement sockets accordingly.
Don't place
components that
could obstruct
M and L sized
add-on boards
Don't forget to
leave room when
enclosing your
hardware in a
Don't obscure
The mikroBUS standard does not dictate the layout of the mainboard beyond the sockets. It's
the responsibility of designers to ensure their mainboards are compatible with add-on boards for
intended applications. These recommendations are based on a few reoccurring scenarios.
If you need additional information about mikroBUS or click boards, place your ticket at www.mikroe.com/support
If you have any questions, comments or business proposals, do not hesitate to contact us at office@mikroe.com