Standard specifications June, 2015
mikroBUS™standard 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.
mikroBUS™standard 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 Placement recommendations 13 14 Page 3
mikroBUS™standard specifications Introduction The mikroBUS™ standard defines mainboard sockets and add-on boards used for interfacing microcontrollers or microprocessors (mainboards) with integrated circuits and modules (add-on boards).
mikroBUS™standard specifications Socket standard Page 5
mikroBUS™standard specifications mikroBUS™ socket standard T he 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).
mikroBUS™standard specifications mikroBUS™ socket standard Silkscreen markings 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. Full mikroBUS™ silkscreen markings 1 4 2 1 3 5 1 6 Front view Rear view 1.
mikroBUS™standard specifications mikroBUS™ socket standard Alternative front markings positioning 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.
mikroBUS™standard specifications mikroBUS™ socket standard Placement requirements 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: Dimensions In-line placement 11.
mikroBUS™standard specifications Add-on board standard Page 10
mikroBUS™standard specifications T mikroBUS™ add-on board standard he 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.
mikroBUS™standard specifications mikroBUS™ add-on board standard Silkscreen markings Required: Optional: 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™standard specifications Appendix Page 13
mikroBUS™standard specifications Appendix Placement recommendations 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.
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