Use DPLL to Lock Digital Oscillator to 1PPS Signal

Michael Morris July 24, 20162 comments
Introduction

There are occasions where it is desirable to lock a digital oscillator to an external time reference such as the 1PPS (One Pulse Per Second) signal output from a GPS receiver. One approach would be to synchronize a fixed frequency oscillator on the leading edge of the 1PPS signal. In many cases, this will result in adequate performance. However, in situations where simple synchronization does not provide adequate performance, digital phase-lock techniques can be applied to a...


Point of View

Christopher Felton August 28, 20146 comments

I was caught of guard when someone commented:

"when a FIR filter is full of multiple loops and complex code, something is wrong"

The comment was made during an informal discussion on alternative hardware description languages (HDL) and was targeted to the straightforward FIR filter implemented in MyHDL

(different FIR description simulation results) 

Personally, (and...


Little to no benefit from C based HLS

Christopher Felton April 4, 2014

Last updated 07-Nov-2015

As I write this I am on a plane and my destination is EELive 2014 where I am going to give a talk hardware design: the grunge era.  It is a shotgun introduction to three alternative hardware description languages (alt.hdl). The three languages briefly introduced in the talk are: bsv, chisel, and myhdl.  The goal of the talk is simply to raise awareness of the three...


Shared-multiplier polyphase FIR filter

Markus Nentwig July 31, 20135 comments

Keywords: FPGA, interpolating decimating FIR filter, sample rate conversion, shared multiplexed pipelined multiplier

Discussion, working code (parametrized Verilog) and Matlab reference design for a FIR polyphase resampler with arbitrary interpolation and decimation ratio, mapped to one multiplier and RAM.

Introduction

A polyphase filter can be as straightforward as multirate DSP ever gets, if it doesn't turn into a semi-deterministic, three-legged little dance between input, output and...


MyHDL FPGA Tutorial II cont. (Echo, Audio Interface)

Christopher Felton September 13, 201210 comments
Introduction

To demonstrate the echo on an FPGA board an interface to an audio ADC/DAC chip will be used. The following will explain the connection to the audio codec and the HDL module used to interface.

Audio Codec Interface

I have two boards with TI AIC23b audio codecs. The AIC23 has a configuration interface (ability to program the registers) and a streaming audio interface. The SPI mode will be used to configure the codec and the I2S interface is used to send and...


FPGA or DSP Processor - Parameters to Make the Right Choice

Muhammad Yasir December 28, 20112 comments

Introduction

Digital Signal Processing (DSP) has a huge global market that is growing fast day by day with rapidly evolving sophisticated modern electronics applications like 3G wireless, voice over internet protocol (VoIP), multimedia systems, radar and satellite systems, medical systems, image-processing applications and consumer electronics. These sophisticated DSP applications pose many conflicting challenges to system designers and application developers in terms of cost and...


Developing FPGA-DSP IP with Python

Christopher Felton March 16, 20101 comment

This blog post was previously titled MyHDL ASIC Proven (How is this related to FPGAs?) but the blog post has been updated and mainly discusses developing FPGA-DSP IP with Python / MyHDL. The original content is still present but the post has been reorganized and expanded. Original post 16-Mar-2010.

Developing FPGA-DSP IP with Python / MyHDL

Using Python to develop DSP logic for an FPGA is very powerful. The Python ecosystem contains many packages including numerical and...


Developing FPGA-DSP IP with Python

Christopher Felton March 16, 20101 comment

This blog post was previously titled MyHDL ASIC Proven (How is this related to FPGAs?) but the blog post has been updated and mainly discusses developing FPGA-DSP IP with Python / MyHDL. The original content is still present but the post has been reorganized and expanded. Original post 16-Mar-2010.

Developing FPGA-DSP IP with Python / MyHDL

Using Python to develop DSP logic for an FPGA is very powerful. The Python ecosystem contains many packages including numerical and...


Use DPLL to Lock Digital Oscillator to 1PPS Signal

Michael Morris July 24, 20162 comments
Introduction

There are occasions where it is desirable to lock a digital oscillator to an external time reference such as the 1PPS (One Pulse Per Second) signal output from a GPS receiver. One approach would be to synchronize a fixed frequency oscillator on the leading edge of the 1PPS signal. In many cases, this will result in adequate performance. However, in situations where simple synchronization does not provide adequate performance, digital phase-lock techniques can be applied to a...


Little to no benefit from C based HLS

Christopher Felton April 4, 2014

Last updated 07-Nov-2015

As I write this I am on a plane and my destination is EELive 2014 where I am going to give a talk hardware design: the grunge era.  It is a shotgun introduction to three alternative hardware description languages (alt.hdl). The three languages briefly introduced in the talk are: bsv, chisel, and myhdl.  The goal of the talk is simply to raise awareness of the three...


Shared-multiplier polyphase FIR filter

Markus Nentwig July 31, 20135 comments

Keywords: FPGA, interpolating decimating FIR filter, sample rate conversion, shared multiplexed pipelined multiplier

Discussion, working code (parametrized Verilog) and Matlab reference design for a FIR polyphase resampler with arbitrary interpolation and decimation ratio, mapped to one multiplier and RAM.

Introduction

A polyphase filter can be as straightforward as multirate DSP ever gets, if it doesn't turn into a semi-deterministic, three-legged little dance between input, output and...


MyHDL FPGA Tutorial II cont. (Echo, Audio Interface)

Christopher Felton September 13, 201210 comments
Introduction

To demonstrate the echo on an FPGA board an interface to an audio ADC/DAC chip will be used. The following will explain the connection to the audio codec and the HDL module used to interface.

Audio Codec Interface

I have two boards with TI AIC23b audio codecs. The AIC23 has a configuration interface (ability to program the registers) and a streaming audio interface. The SPI mode will be used to configure the codec and the I2S interface is used to send and...


FPGA or DSP Processor - Parameters to Make the Right Choice

Muhammad Yasir December 28, 20112 comments

Introduction

Digital Signal Processing (DSP) has a huge global market that is growing fast day by day with rapidly evolving sophisticated modern electronics applications like 3G wireless, voice over internet protocol (VoIP), multimedia systems, radar and satellite systems, medical systems, image-processing applications and consumer electronics. These sophisticated DSP applications pose many conflicting challenges to system designers and application developers in terms of cost and...


Point of View

Christopher Felton August 28, 20146 comments

I was caught of guard when someone commented:

"when a FIR filter is full of multiple loops and complex code, something is wrong"

The comment was made during an informal discussion on alternative hardware description languages (HDL) and was targeted to the straightforward FIR filter implemented in MyHDL

(different FIR description simulation results) 

Personally, (and...