Logi-Pi User Guide
From ValentFx Wiki
LOGi Pi - Bringing FPGA Technology to the Raspberry Pi
Contents
1 Overview
1.1 Features
1.2 Peripherals
2 Electrical
3 Interfacing
3.1 Top Level Block Diagram
3.2 RA2.1 Raspberry Pi Connector Interface
3.3 PMOD Expansion Port
3.4 Arduino Expansion Port
3.5 LVDS Expansion Port
3.6 LVDS signal usage
3.7 Push Button Usage
3.8 DIP Switch Usage
3.9 LED Usage
3.10 JTAG Interface
4 Programming the FPGA from the Raspberry Pi
5 Raspberry Pi SPI to FPGA Interface
5.1 Direct SPI Communication to FPGA
5.2 SPI to Wishbone Interface Bandwidth
6 Useful Links
6.1 LOGi - Repository - Projects, Libraries, Drivers
6.2 LOGi-Pi Schematics
6.3 LOGI-Pi User Guide -LOGi-Pi documentation
6.4 LOGi Projects wiki - LOGI and Users projects will be documented here
Overview
The LOGi-Pi is the first FPGA development platform that has been optimized for use with the Raspberry Pi. The
LOGi-Pi adds FPGA flexibility and capability that allows the Raspberry Pi to be easily morphed into endless digital
applications. The FPGA/CPU combination the LOGi-Pi creates an incredibly powerful and versatile digital canvas
for users to create their imaginative digital designs.
Features
FPGA: Spartan 6 LX9 – TQFP144 Package - XC6SLX9-2TQG144C
Plug and play interfacing the Raspberry Pi
Arduino Shield expansion allowing for more than 200 existing plug in hardware modules
PMOD compatible headers allowing for more than 50 existing low cost hardware modules
4 layer optimized design to support maximum performance of high bandwidth applications
Length tuned GPMC, SDRAM and LVDS signals for high performance applications
50 Mhz MEMS oscillator
Peripherals
2x Push buttons
2x DIP Switch
1x High bandwidth SATA connector expansion port
44 FPGA IO available through PMOD and Arduino headers
2x Digilent Inc. PMOD ports supporting 59+ plug and play hardware modules
1x Arduino Header supporting 200+ Arduino Shield modules
Optional I2C, SPI access from the Beaglebone
10x length matched LVDS pairs routed as: 100 ohm differential, 50 ohm single-ended
256 Mb SDRAM
Electrical
External Vin Connector
Voltage Max. Voltage Min.
6V 4V
The LOGi-Pi can be powered through the Raspberry Pi connector or from the on-board external power
connector. If powering the LOGi-Pi from the Raspberry Pi connector, it is recommended that a 1A external
power supply be used to power the Raspberry Pi. Most FPGA applications will not require the use of a separate
external power supply to power the LOGi-Pi, but it is up to to ensure that the FPGA applications will not overload the Raspberry Pi power rails which will cause brown-outs and or system failures.
All current LOGi applications can be run while being powered only from the Raspberry Pi connector. The user
should test newly designed applications to ensure the FPGA load falls within acceptable values. Information
relevant to the Raspberry Pi system power requirements can be found the Raspberry Pi wiki.
The LOGi-Pi uses LDO regulators to supply 3V3 and 1V2 to the onboard peripherals and the FPGA in order to
reduce costs. The power distribution was designed to allow maximum dissipated heat to the internal and external
power planes. If very high demand applications are designed testing should be done to ensure that the LDO
regulators are not overheated due to the heavy loads. All current applications have been tested including the heavy
load of the bitcoin mining applications and no over-heating issues have been found.
Interfacing
The LOGi-Pi was designed to allow for easy expansion to a maximum number of off-the-shelf hardware modules.
The LOGI-Pi uses Digilent Inc. PMOD expansion ports and an Arduino Shield expansion port that give users a
plug-and-play experience with over 250 off-the-shelf hardware modules. A SATA port was added to board to be
used for maximum bandwidth applications. There are 10 LVDS pairs routed on the board that are all length
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