I have detailed the implementation of a BFO stage for detecting metal. Now it has been validated on the bench, the next step is to integrate it in a stand alone instrument for testing on the field. A few things have to be done to reach this goal:

• make a...]]> Sat, 06 Feb 2016 16:27:01 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/911.php Introduction
• Theory
• Electronics
• Software
• Tests
• References
• Next part: building the detector
1. Introduction

This article discusses the implementation of a beat frequency oscillator (BFO) stage for metal detector. While they are mentioned here and there, the article does not detail other important electronic stages such as the power supply, and user interface, the coil or...]]> Sat, 30 Jan 2016 17:39:21 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/854/an-absolute-position-encoder-vhdl-core Let's consider motorized systems controlled by electronics. A closed loop architecture looks like this:

The following components are involved:

• the motor itself (DC, stepper ...),
• the controller, in charge of computing position according to the whole system state,
• the driver board in charge of generating signals and power for the motor,
• the position...]]> Wed, 11 Nov 2015 10:42:51 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/850.php In recent projects, I found myself working with data acquisition systems. For instance:

• PCIe/10GbE readouts for 2D XRay detectors (RASHPA slides, RASHPA paper)
• instruments mixing 1D signal acquisition and triggering,
• microcontroller based system for audio transmission: (NRF...]]> Sun, 08 Nov 2015 13:32:48 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/775.php With another colleague at work, we are currently developing an electronic board that will eventually be powered over Ethernet. To gain more experience with this technology, we prototyped a standalone power supply stage.

  We want to test this stage with different load profiles. While we already have professional grade active loads at work, I had previously read about the...]]> Thu, 23 Apr 2015 09:10:21 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/626.php A few weeks ago, I bought a set of cheap wireless outlets and reimplemented the protocol for further inclusion in a domotics platform. I wrote a post about it here:

  //www.embeddedrelated.com/showarticle/620.php

  Following that, I had access to another outlet from a different vendor:

  Tue, 12 Aug 2014 22:37:02 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/620.php I am improving the domotics framework that I described in a previous article://www.embeddedrelated.com/showarticle/605.php

  I want to support wireless wall outlets, allowing me to switch devices power from a remote location over HTTP.

  To do so, I could design my own wireless wall outlets and use a hardware similar to the previous one, based on the NRF905 chipset. The problem is...]]> Sat, 19 Jul 2014 20:25:44 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/605.php I have been thinking for a while about a system to monitor the states of my flat and my garage doors from a remote place. Functionnaly, I wanted to monitor the state of my doors from a remote place. A typical situation is when I leave for holidays, but it can also be useful from the work office. To do so, I would centralize the information on a server connected on the Internet...]]> Tue, 10 Jun 2014 15:19:22 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/603.php Some weeks ago, I published an article on how we used the PRU to implement a power supply control loop having hard realtime constraints:

  //www.embeddedrelated.com/showarticle/586.php

  Writing this kind of logic in assembly language is not easy. First the assembly language itself may be difficult to learn depending on your background. Then, fixed and floating point arithmetics...]]> Sat, 07 Jun 2014 13:32:23 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/586.php I work as an engineer in a synchrotron facility. A few weeks ago, I helped the people in charge of the power supply developments to integrate a realtime control algorithm on a prototype platform: a BeagleBone Black (BBB) running Linux. I had already worked with this board in the past, and I found it very interesting given its excellent resources versus price ratio (around 40...]]> Fri, 25 Apr 2014 23:13:45 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/548.php http://www.electrodragon.com/w/NRF905_Transceiver_433MHz-Wireless_ModuleThe PTR8000 is based on the dual band sub 1GHz NRF905 chipset from NORDICSEMI: Mon, 27 Jan 2014 11:37:23 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/459/introducing-the-vpcie-framework My daily work involves platforms featuring an embedded CPU communcating with a FPGA device over a PCI Express link (PCIe for short). The main purpose of this link is for the CPU to convey configuration, control, and status commands to hardware slaves implemented in the FPGA. For data intensive applications (2D XRay detector readout backend), this link can also be used as a DMA...]]> Sat, 31 Aug 2013 19:47:58 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/176.php I am currently working on a voltage controller running on a ATMEGA328P, ATMEL AVR 8 bits microcontroller. The controller logic is implemented in the main() routine and relies on a periodical timer whose frequency is fixed at application setup. Among other things, the timer ISR handler increments some per tick counters which are then used by the main routine to implement the voltage controller...]]> Wed, 22 May 2013 10:20:59 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/173.php I am increasingly asked to work on small spare time projects where a user needs to control some device over the INTERNET. Recently, a friend needed to control heater relays and measure the temperature of its geographically distant secondary house. Another case relates to the control of a pan tilt home monitoring camera. A last one is the control of an old XY plotter DACs.

  In...]]> Tue, 07 May 2013 09:06:12 +0000 Fabien Le Mentec https://www.embeddedrelated.com/showarticle/172.php Abstraction is a key to manage software systems as they increase in size and complexity. As shown in a previous post, abstraction requires a developper to clearly define a software interface for both data and functions, and eventually hide the underlying implementation.When using the C language, the interface is often exposed in a header '.h' file, while the implementation is put...]]> Mon, 29 Apr 2013 18:53:51 +0000 Fabien Le Mentec