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BeagleWire - FPGA development cape for the BeagleBone

The BeagleWire is an FPGA development platform that has been designed for use with BeagleBone boards. BeagleWire is a cape on which there is FPGA device - Lattice iCE40HX. The Lattice iCE40 is a family of FPGAs with a minimalistic architecture and very regular structure, designed for low-cost, high-volume consumer and system applications. The significance of FPGAs is continuously increasing, as they are more and more often used for supporting work of ARM processors. BeagleWire does not require external tools (JTAG) and the whole software is Open Source. iCE40 is an energy saving device, allowing to work with small batteries. FPGA cape allows easy and low cost start for beginners who would like to take their first steps in working with FPGAs. The developed software will be an easy and, at the same time, efficient tool for communication with FPGA. At this point FPGA will be able to meet the requirements of even more advanced applications. The BeagleWire creates a powerful and versatile digital cape for users to create their imaginative digital designs.

BeagleWire features:

  • FPGA: Lattice iCE40HX4K - TQFP 144 Package
  • GPMC port access from the BeagleBone
  • SPI programming port from the BeagleBone
  • 4 layer PCB optimized design to support maximum performance for high bandwidth applications
  • BeagleBoard optimized - compatible with BeagleBone Black, BeagleBone Black Wireless, element14 BeagleBone Black Industrial
  • does not require external tools (JTAG)
  • minimalistic architecture and very regular structure
  • energy saving device allows to work with small batteries
  • lower application costs
  • fully open-source toolchain

BeagleWire Peripherals:

  • 32 MB SDRAM
  • 100Mhz external clock
  • 4 LEDs
  • 4 PMOD connectors
  • 4 Grove connectors
  • 2 user push buttons
  • 2 input DIP switch

Software\Driver support

BeagleWire software support is still developing. You can find there a lot of useful examples and ready to use solutions. For communication between FPGA and ARM, We can use the GPMC. This is an easy and efficient solution. BeagleWire software repostitory has special components for it. You can just mapping your logic in BeagleBone memory. A lot of examples has kernel driver e.g. SPI, GPIO. After preparing the FPGA device you can use it as typical GPIO/SPI from user space. A part of examples which don't belong to kernel subsystems e.g. rotary excoder, ultrasonic ranger sensor or blink leds. In this examples You can connect which FPGA using write/read operation for /dev/mem file.


The project is the result of the community work and it is still developing. If you can support this project or do you have any questions, feel free to ask as.
Michael Welling
Patryk Mezydlo


BeagleWire KiCAD Repository
BeagleWire Software Repository
BeagleWire project page
BeagleWire project page
BeagleWire Schematic

User Manual

Board Diagram

Bw diagram.png

Expansion Ports, Interfaces and Peripherals

GPMC Communications interface

The general-purpose memory controller (GPMC) is a unified memory controller dedicated to interfacing external memory devices: SRAM-like memories and application-specific integrated circuit (ASIC) devices, asynchronous, synchronous, and page mode (only available in non-multiplexed mode) burst NOR flash devices, NAND Flash, Pseudo-SRAM devices. The GPMC bus allow for a high bandwidth interface between the FPGA and the ARM processor. GPMC controller is configured from the DTS file. GPMC pins are brought out to BeagleBone P8/P9 headers. BeagleWire software repository contains a component writing in Verilog which support communications between FPGA and ARM.

SPI Programming interface

Programming is done by SPI interface. BeagleWire uses second BeagleBone SPI port. SPI frequency should be between 1Mhz and 25Mhz.

PMOD Expansion Ports

BeagleWire contains four Digilent Inc. Pmod ports. The Pmod standard has a lot of ready modules. Thanks to four Pmod ports We can use as many as 24 additional pins.


There are four blue LEDs.

DIP Switch

BeagleWire has two DIP switch. "ON" position is treated as logical zero.

Push Button

There are two user buttons. We used schmitt trigger, this is simple structure which protect us from buttons bouncing.

Additional common IRQ lines

Two lines are connected directly between BBB and BW. These lines don't have destiny. In many application there are using as interrupt lines.

SDRAM Memory

BealgeWire has 32 MB SDRAM memory. BeagleWire software repository contains a simple SDRAM controller writing in Verilog which support communications between SDRAM and iCE40.

Grove Expansion Ports

BeagleWire contains four Grove connectors. First and second connectors used to I2C. Other connectors don't have destinations.

External clock source

BeagleWire has external clock generator. There is 100Mhz You can change clock speed using internal PLL.


More information about I/O connections you can find in:BeagleWire pcf file or BeagleWire Schematic

Connection BeagleWire with BeagleBone (P8/P9 Connector Pin Usage)

Quick Start Guide

Prepare BBB Image

Prepare custom kernel image, is easy instruction how to do it here: BBB prepare image instruction. Attach(<M>) FPGA-mgr and iCE40-spi driver. Version of linux kernel should be 4.12 or newest.

 Device Drivers ---> FPGA Configuration Support --->  <M> FPGA Configuration Framework 
                                                      <M>      Lattice iCE40 SPI   

Writeing EEPROM configuration contents

BeagleWire cape has a EEPROM memory, so that the BBB device overlay is automatically loaded up on each boot up. EEPROM contents and loading script are located in BeagleWire software repository.
Check BW_EEPROM.bin content:

$ xxd  BW_EEPROM.bin

It should look like this:

00000000: aa55 33ee 4131 4265 6167 6c65 426f 6e65  .U3.A1BeagleBone
00000010: 2042 6561 676c 6557 6972 6543 6170 6500   BeagleWireCape.
00000020: 0000 0000 0000 3030 4130 6265 6167 6c65  ......00A0beagle
00000030: 626f 6172 642e 6f72 6700 4257 2d49 4345
00000040: 3430 4361 7065 0000 0000 3030 4257 5245  40Cape....00BWRE
00000050: 5630 3230 3137 0000 0000 0000 0000 0000  V02017..........

Load EEPROM using script:

$ sudo ./

Device Tree Overlay

Device Tree is required for enabling SPI and GPMC.
Install the DTS compiler:

$ wget -c
$ chmod +x
$ ./

Compile the dts file:

$ dtc -O dtb -o DTS/BW-ICE40Cape-00A0.dtbo -b 0 -@ DTS/BW-ICE40Cape-00A0.dts

Copy dtbo file to /lib/firmware on the BBB:

$ cp BW-ICE40Cape-00A0.dtbo /lib/firmware

Installing the IceStorm toolchain

Install toolchain on PC or BBB.
On PC:

$ sudo ./


$ sudo ./ BBB

Synthesizing Verilog code using IceStorm toolchain

Prepare Verilog module for first FPGA programming

module top(input clk, output [3:0] led);

	reg [27:0] counter = 0;
	always @(posedge clk) counter <= counter + 1;

	assign led[0:3] = counter[24:27];

PCF file is using for associating input/output module signals with physicals pins in FPGA device.

set_io clk 61

set_io led[0] 28
set_io led[1] 29
set_io led[2] 31
set_io led[3] 32 


PROJ = blink          # project name
BUILD = ./out         # output directory
DEVICE = 8k           # device
FOOTPRNT = tq144:4k   # device package
SRC = top.v           # top module name
SRC +=                # additional module name      
PIN_SRC = pinmap.pcf  # pcf file name

.PHONY: all load clean

	mkdir -p $(BUILD)
	yosys -p "synth_ice40 -top top -blif $(BUILD)/$(PROJ).blif" $(SRC)
	arachne-pnr -d $(DEVICE) -P $(FOOTPRNT) -p $(PIN_SRC) -o $(BUILD)/$(PROJ).asc $(BUILD)/$(PROJ).blif
	icepack $(BUILD)/$(PROJ).asc $(BUILD)/$(PROJ).bin
	echo -e "\x0\x0\x0\x0\x0\x0\x0" >> $(BUILD)/$(PROJ).bin
	dd if= $(BUILD)/$(PROJ).bin of=/dev/spidev1.0

	rm -rf ./$(BUILD)/

Programming the FPGA from the BeagleBone

Will be soon.


BeagleWire software repository has a lot of different source. Here I'm showing you how to use it. We can divided examples for two parts. The first part are the simplest examples which don't have own subsystem in Linux kernel e.g. rotary excoder, ultrasonic ranger sensor or blink leds. In this examples We can connect which FPGA using write/read operation for /dev/mem file. The second part are the examples with kernel driver e.g. SPI, GPIO.