New Horizons

Welcome to my blog

My name is Sven Andersson and I
work as a consultant in embedded
system design, implemented in ASIC
and FPGA.
In my spare time I write this blog
and I hope it will inspire others to
learn more about this fantastic field.
I live in Stockholm Sweden and have
my own company


You are welcome to contact me
and ask questions or make comments
about my blog.


New Horizons
What's new
Starting a blog
Writing a blog
Using an RSS reader

Zynq Design From Scratch
Started February 2014
1 Introduction
Changes and updates
2 Zynq-7000 All Programmable SoC
3 ZedBoard and other boards
4 Computer platform and VirtualBox
5 Installing Ubuntu
6 Fixing Ubuntu
7 Installing Vivado
8 Starting Vivado
9 Using Vivado
10 Lab 1. Create a Zynq project
11 Lab 1. Build a hardware platform
12 Lab 1. Create a software application
13 Lab 1. Connect to ZedBoard
14 Lab 1. Run a software application
15 Lab 1. Benchmarking ARM Cortex-A9
16 Lab 2. Adding a GPIO peripheral
17 Lab 2. Create a custom HDL module
18 Lab 2. Connect package pins and implement
19 Lab 2. Create a software application and configure the PL
20 Lab 2. Debugging a software application
21 Running Linux from SD card
22 Installing PetaLinux
23 Booting PetaLinux
24 Connect to ZedBoad via ethernet
25 Rebuilding the PetaLinux kernel image
26 Running a DHCP server on the host
27 Running a TFTP server on the host
28 PetaLinux boot via U-boot
29 PetaLinux application development
30 Fixing the host computer
31 Running NFS servers
32 VirtualBox seamless mode
33 Mounting guest file system using sshfs
34 PetaLinux. Setting up a web server
35 PetaLinux. Using cgi scripts
36 PetaLinux. Web enabled application
37 Convert from VirtualBox to VMware
38 Running Linaro Ubuntu on ZedBoard
39 Running Android on ZedBoard
40 Lab2. Booting from SD card and SPI flash
41 Lab2. PetaLinux board bringup
42 Lab2. Writing userspace IO device driver
43 Lab2. Hardware debugging
44 MicroZed quick start
45 Installing Vivado 2014.1
46 Lab3. Adding push buttons to our Zynq system
47 Lab3. Adding an interrupt service routine
48 Installing Ubuntu 14.04
49 Installing Vivado and Petalinux 2014.2
50 Using Vivado 2014.2
51 Upgrading to Ubuntu 14.04
52 Using Petalinux 2014.2
53 Booting from SD card and SPI flash
54 Booting Petalinux 2014.2 from SD card
55 Booting Petalinux 2014.2 from SPI flash
56 Installing Vivado 2014.3

Chipotle Verification System

EE Times Retrospective Series
It all started more than 40 years ago
My first job as an electrical engineer
The Memory (R)evolution
The Microprocessor (R)evolution

Four soft-core processors
Started January 2012
Table of contents
OpenRISC 1200
Nios II

Using the Spartan-6 LX9 MicroBoard
Started August 2011
Table of contents
Problems, fixes and solutions

FPGA Design From Scratch
Started December 2006
Table of contents
Acronyms and abbreviations

Actel FPGA design
Designing with an Actel FPGA. Part 1
Designing with an Actel FPGA. Part 2
Designing with an Actel FPGA. Part 3
Designing with an Actel FPGA. Part 4
Designing with an Actel FPGA. Part 5

A hardware designer's best friend
Zoo Design Platform

Installing Cobra Command Tool
A processor benchmark

Porting a Unix program to Mac OS X
Fixing a HyperTerminal in Mac OS X
A dream come true

Stockholm by bike

The New York City Marathon

Kittelfjall Lappland

Tour skating in Sweden and around the world
Wild skating
Tour day
Safety equipment
A look at the equipment you need
Skate maintenance
Books, photos, films and videos
Weather forecasts

38000 feet above see level
A trip to Spain
Florida the sunshine state

Photo Albums
Seaside Florida
Ronda Spain
Sevilla Spain
Cordoba Spain
Alhambra Spain
KittelfjÀll Lapland
Landsort Art Walk
Skating on thin ice

100 Power Tips for FPGA Designers

Adventures in ASIC
Computer History Museum
Design & Reuse
d9 Tech Blog
EDA Cafe
EDA DesignLine
Eli's tech Blog
FPGA Arcade
FPGA Central
FPGA developer
FPGA Journal
FPGA World
Lesley Shannon Courses
Mac 2 Ubuntu
Programmable Logic DesignLine
World of ASIC

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Thursday, April 19, 2007
FPGA design from scratch. Part 21
Debugging IP blocks

All Xilinx IP blocks are protected, meaning we don't have access to the RTL code and we can't probe internal nodes during a simulation. This makes debugging complicated. We can only observe input and output signals to the IP block and we have no idea what is going on inside the block.

The reset logic

The OPB_V20 design includes several sources for bus reset. A power-on reset circuit asserts the OPB_Rst for 16 clock cycles anytime the FPGA has completed configuration. External resets that occur during the 16 clock reset time are ignored. After the 16-clock reset has completed, external resets can be applied to the OPB_V20 reset signals. The external resets are: SYS_Rst (can be configured as high-true or low-true), WDT_Rst, and Debug_SYS_Rst. SYS_Rst is the main user reset for the OPB and can be connected to internal logic or an external signal or switch.
WDT_Rst can be connected to the reset output of a Watchdog Timer to allow for OPB resets in the event of a watchdog time-out. Debug_SYS_Rst can be connected to the reset output of a debug peripheral, such as the JTAG UART, so that the debugger can remotely reset the OPB. SYS_Rst, WDT_Rst, and Debug_SYS_Rst are synchronized to the OPB_Clk in the OPB_V20, but the width of these signals is otherwise unaltered.

Reset signal polarity

What is the polarity of the reset signal. Here is the specification for the opb_v20 setup, taken from the ETC_system.mhs file.

BEGIN opb_v20
 PORT SYS_Rst = sys_rst_s
 PORT OPB_Clk = sys_clk_s

The PARAMETER C_EXT_RESET_HIGH = 0 specification means that the reset signal is active low.

The system reset SYS_rst goes to the opb_mb block and should propagate through this block and generate the inverted OPB_rst signal.

MicroBlaze reset

When a Reset (OPB_rst) or Debug_Rst  occurs, MicroBlaze will flush the pipeline and start fetching instructions from the reset vector (address 0x0). Both external reset signals are active high, and should be asserted for a minimum of 16 cycles.

All output signals are defined from the opb_mb block and we have the reset signal to the MicroBlaze processor coming through. We are ready for more advanced simulations. First we have to study how the MicroBlaze processor operates. Here is the MicroBlaze Processor Reference Guide.

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