Michael Morris Blog on FPGARelated.com

Computing Fixed-Point Square Roots and Their Reciprocals Using Goldschmidt Algorithm

Michael Morris — Mon, 15 Jun 2020 00:20:49 +0000

Introduction

A well known algorithm for computing square roots by iteration is provided by the Newton-Raphson Algorithm. The algorithm determines the square root using iteration until the root has been determined to some user-defined level of accuracy. The method is easily derived. First, describe a number in terms of its square root:

$$ a = y ^ {2} ,$$

where $y = \sqrt{a}$. The value of the...

Use DPLL to Lock Digital Oscillator to 1PPS Signal

Michael Morris — Sun, 24 Jul 2016 12:57:11 +0000

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...

Use a Simple Microprogram Controller (MPC) to Speed Development of Complex Microprogrammed State Machines

Michael Morris — Sat, 18 Apr 2015 17:47:58 +0000

Introduction

This article will describe a synthesizable HDL-based microprogram controller (MPC), or microprogram sequencer (MPS), that can be used to provide the control of a microprogrammed state machine. Unlike the microprogrammed state machines that I described in my previous two articles, "Use Microprogramming to Save Resources and Add Functionality" and

Fit Sixteen (or more) Asynchronous Serial Receivers into the Area of a Standard UART Receiver

Michael Morris — Mon, 30 Mar 2015 01:29:57 +0000

Introduction

This article will describe a technique, available in many current FPGA architectures, to fit a large amount of logic into a small area. About ten years ago now (Feb/Mar 2005), I helped develop a multi-line Caller ID product. The Multi-Channel Asynchronous Receiver (MCAR) FPGA core developed for that product will be used to illustrate the technique(s) needed to fit a 16...

Use Microprogramming to Save Resources and Increase Functionality

Michael Morris — Sat, 21 Mar 2015 03:26:17 +0000

Introduction

Microprogramming is a design approach that every FPGA designer should have in their bag of tricks. I subscribe to the concept that microprogramming is a structured approach to the design of state machines. This is essentially the view of Maurice Wilkes when he first proposed microprogramming in 1951 as an alternative method for the implementation of...