Category Archives: Electronics

FTDI TTL232R-3V3 to Visonic PowerMax

Online information on RS232 communication with a Visonic PowerMax Plus/Pro home security system describes the pinout of a 10-pin header. The photograph below shows the 4-pin RS232 interface of a regular PowerMax system. Counting from left to right, the RXD (yellow wire) of the FTDI TTL 3V3 cable connects to pin 2. Pin 3 is used for TXD (orange wire). The fourth pin is used for ground (black wire).

uCurrent Gold damaged

Today my EEVblog uCurrent Gold got fried in an experiment. 😥 The idea was to measure the current of a power supply to a circuit board on a Saleae Logic 8 Pro. So, the current input of the uCurrent was connected in series between the power supply and the circuit board. The output voltage of the uCurrent was connected to an input of the Logic. The supply voltage was measured on a second input of the Logic. Both voltages were measured with respect to the negative side of the power supply.

ucurrent_friedStupid stupid stupid. The inputs and outputs of the uCurrent Gold are not isolated and both negative binding posts are connected with a tiny trace. Connecting the uCurrent Gold in series with the positive lead to the circuit board caused that tiny trace (along the bottom side of the board in the photograph above) to act as fuse. My bad, but I must say Dave left some room for improvement in revision 6. The uCurrent was recovered with a bypass operation and a big label was installed on the box as reminder of the common negative. The experiment worked a lot better with the uCurrent tinned-Gold connected in series in the negative lead from the circuit board to the power supply.

Xilinx Vivado 2014.4 and the Digilent ZYBO tutorial

The Digilent Inc. “Embedded Linux® Hands-on Tutorial for the ZYBO” is available from the Digilent website in PDF format (revision July 17, 2014). Another version of the tutorial is available on The tutorial attempts to get you through quite some steps. A little extra help is sometimes needed to have success. This post will document my findings for future use.

The notes below have been made while going through the tutorial with Xilinx Vivado 2014.4 on an Ubuntu 14.10 64-bit install. The Xilinx SDK is required as part of the Vivado package. Note that both Vivado and the SDK have dedicated settings files (e.g., which need to be sourced both to set the required environment variables. Continue reading

Instrument of Things

The Instrument of Things project shows how to extend your custom electrical instruments with industry-standard capabilities for remote control via a TCP/IP interface. The WIZnet WIZ550io module is used to enable a basic web server, a portmap service, and a server for the remote control of the instrument using the VXI-11 communications protocol. The ultimate goal for the Instrument of Things is to easily add the VXI-11 communications protocol and LAN eXtensions for Instruments (LXI) technology to any electrical instrument project.
Continue reading

Spark Core browser control

The Spark Core is a tiny module with ARM Cortex M3 micro-controller and Wi-Fi interface. These devices will be connect with the Spark Cloud service for firmware updates and remote control. A limited amount of pins on the module can be used for analog and digital signals. The firmware of the Spark Core can be programmed, compiled and uploaded using the Spark Web IDE.

The following code is for a Spark Core installed on the Spark relay shield. All relays are controlled using a single function. Up to four functions are currently supported by Spark. The status of the four relays can be read through a single variable.

Continue reading

Rigol DS2072

This page will present some projects with my Rigol scope. For now, just a remark on the first firmware update I received (00.00.01 to 00.01.01). The procedure stresses to update the firmware with a blank screen. The steps to get to this boot screen are according to the procedure to:

  1. “Press the power on button on the front panel of the instrument. All of the buttons will light.”
  2. “Repeatedly press the Help key on the front panel. All of the buttons will unlight.”
  3. “The Single light will illuminate.”

Instead of the step-by-step instruction given by Rigol, the trick is to press and release the ‘Help’ button during the one second all LEDs on the scope are on after pressing the power button. If you wait for all of the buttons to light, you are too late. If you have to press the Help key repeatedly, you are too late. The boot procedure of the scope should stop before the Rigol logo is shown and the ‘SINGLE’ button should be lit. The rest is like a walk in the park.

The update procedure for the most recent firmware updates ( and confirm the above. It’s disappointing though to see that some more obvious bugs in the firmware itself still have not been fixed yet.

There have been reports on a hack of the DS2072 to increase the bandwidth from 70 MHz to 200 MHz and unlock all features. I might consider this in the near future, when the timers of the evaluation period have stopped and the warranty period of my scope has ended.

DLP-TH1b Temperature Humidity Sensor

Recently I have ordered a FT2232HQ mini-module from the webshop of Future Technology Devices Ltd. for use in an ongoing project with a Xilinx Spartan FPGA. In addition, I ordered a DLP-TH1b data acquisition module as a working application of a FTDI USB UART to play around with. Unfortunately, the source code for Linux systems on the website of DLP Design did not work at all. Opening the black sensor box revealed a Sensirion SHT11 humidity and temperature sensor. The source code has been changed a little using the datasheet of this device and the D2xx programmer’s guide of FTDI. My version is available for download using this link: dlp_th1b.tar.gz.