TI Stepper Drivers DRV8818 and DRV8824

I’ve been working on a XMOS CNC controller board and in the process came up with two prototype designs using two different Texas Instruments stepper driver IC’s. The DRV8818 and the DRV8824.  Both of these ended up being able to control the NEMA 17 steppers for RepRap and the NEMA 23 for my small CNC router .

DRV8818 Board


DRV8824 Board



HP 5328a Frequency Counter Fix.

I purchased a HP 5328a counter off ebay for a decent price.  It arrived a few days later and I’d say cosmetically its a 9.9/10.  After putting it on the bench and turning on the unit I released it didn’t have the oven based oscillator.  It did have channel C option and GPIB interface.  After checking channel A I was really glad to see that things were working correctly.  I moved over to test channel C.  All was well I thought until I noticed that the connector on channel C seems to work intermittanly.  After pulling the cover off I was pleased to see the unit was very clean inside.  I removed the channel C card by taking a single screw out from the rear to remove the top cover.  Removing the BNC was just a simple process of removing the nut.  After taking the connector apart it was tarnished quite a bit.  Some cleaning and I did apply a bit of pressure.  After assembly the C channel was working perfectly.


HP 8935 CDMA Service Monitor EL Display Adapter / Converter

After a lengthy stretch of research on the EL 512×256 Planar display I finally gave up trying to get a datasheet for it.  If you happen to have a datasheet I’d love to get a copy.  Planar didn’t have one or so I’m told by there rep.  After a bit of reverse engineering I was able to figure out the output to the display.  I prototyped it on a large FPGA dev board but then wondered if it would be possible to find a usable LCD to fit the frame and to use something a bit more practical to do the conversion.  I have gotten a few responses back from other 8935 owners that they might be interested in a conversion kit of sorts based on what I have done so far.  I also wonder if the E8285A has the same display. If somebody has a E8285A I’d like to know if it has the same display because that might make it worth putting together a kit.  For now I just seem to take a step further and further towards a complete solution each time I power up my 8935 and struggle to tell what input is in the lower part of my screen.

Here is a photo in case you have something similar.  (Note the pilot production tag)


HP 8935 E6380A EL Display Fix

I have a HP 8935 E6380A service monitor that had some pretty severe screen burn.  After looking around for a replacement I wanted to see how hard it would be to adapt a current LCD to the 8935.  Suprisingly it was fairly easy.  I had a 10.5 inch display and after probing around a bit to see what signals/power were on the A1A1 connector (400 i think) I started playing with a FPGA dev board to convert signals to something I could see on the screen.  It works but doesn’t fill the entire screen and its not the right size hardware.  Now that I have a PLAN B and I’ve found a 6.5″ish lcd I can readily buy cheap, I’ll troll along with the burnt display till it fails or I can’t stand it anymore. I’m hoping there is a lot of interest in this to other 8935 owners and its something I can justify doing in the near future.

Some things I played with while I had the 8935 apart and the 10.5″ connected:

– Inversion to have some way of preventing screen burn.

– Adding some color (Changed boarder color, changed color of spectrum analyzer portions of the screen) This isn’t something that can be done everywhere. If its simply which pixels get what color it’s trivial.

– Added text to the parts of the screen not used going from 512×256 to 640×480.  Could add ADC to show voltages etc as extra info.

-Centered screen and added border.


Digital Modem Codec and SDR

I’ve be looking at several platforms to do DSP work in relation to a SDR and digital modems.  I have a xmos demo board and some AVR32 items laying around which I needed nice DAC/ADC to interface with.  The TLV320AIC23 is a nice inexpensive codec.  I built a small prototype board to use the chip in development products and later I’ll turn this into a module that can just be plugged in to various projects.  This board can be used with a small MCU 16-32 bit to do APRS, GSMK (DSTAR), P25 and various other digital demod/mod.  The board breaks of all of the TLV320 channels for both input and output.


I’ve been working on a hardware to spin up a homegrown DMR/NEXEDGE/VOIP/DSTAR switch using freeswitch, some AMBE hardware, and common DMR radios (Hytera and Mototrbo) for use in Ham.  I have been working a board design I did last year to handle the AMBE codec.  The basic idea is to have a way to convert the AMBE codec to G711 to allow interface to other systems.  It also allows trunking/routing between systems.  If this something you might be interested in doing or helping with please let me know.  I’m really interested in hardware donations including NEXEDGE, DSTAR, and Hytera gear.


TM-710A Keyboard Adapter Design

Interest during the last few months is very sparse on the TM-710A Keyboard adapter.  I haven’t’ put much work into it since I’ve found other options.   I do not plan on doing any more kits for this board at this time. This is a option for anyone that did not complete an initial build.

The concept used on the board is to drive the normal mic with a AVR chip and emulate the mic on the TM-710 board which is controlled by the AVR.  Software will have to be completed to come up with something useful and this design may not be perfect.  I have used this board and the previous OSW board in my mobile setup for a long time without any issues but have switched to using a SSD based PC.
Continue reading “TM-710A Keyboard Adapter Design”

SBAMAT – ADG728 Module PCB Board

I did an update for the SBAMAT board.  This board is a breakout board for the ADG728.

The ADG728 is a CMOS analog matrix switch with a serially controlled 2-wire interface. It is an 8-channel matrix switch. On resistance is closely matched between switches and very flat over the full signal range. This part can operate equally well as a multiplexer, demultiplexer or switch array and the input signal range extends to the supplies.


If you need a neat analog mux this board is great for prototyping.  If you would like to build your own board the gerbers are here Gerbers SBAMAT.

SB710Key – TM-D710A Keyboard Adapter

Prototype boards have arrived.  I’ll be working with these for the next few weeks to hopefully finalize a line powered PS2 keyboard adapter for the Kenwood TM-D710A.  Here are some pics of the proto board.07/14/2011 – UPDATE waiting on some missing parts to arrive in mail.

07/20/2011 – All parts arrived except for the osc. It’s on backorder for at least two weeks.

07/29/2011 – Still no osc.  I’m researching alternatives.

08/05/2011 – Finally located something that should work.  2 week leadtime on this part so more waiting.

11/30/2011 – I ‘ve assembled and tested the few boards I had left and due to limited application of this I will be doing some sort of open source release of the project in December for those that want to build one of these and improve the software.

OSW 1.0D Kit TM-D710A keyboard adapter.

05/02/2011  07:12 AM – The order for the 1.0D board has been processed and passed design checks with manufacture.  We all should see boards from the group buy in the next 3-4 weeks hopefully.  Parts have already arrived.  I’ll be posting more information and documentation during those long 3-4 weeks of waiting here.  I recommend to everyone to use an AVR platform for MCU development an interface but you are welcome to use what you want.  The goal is to end up with something that is under the 100ma current of the MIC interface. Read more…

Continue reading “OSW 1.0D Kit TM-D710A keyboard adapter.”

OSW Board TM-D710A Keyboard Interface revisted.

04/21/2011  08:00PM EST

I have gotten back to this as promised tonight and almost have a prototype of something new for folks wanting to interface with there TM-D710A.  I’m am tediously taking the CPLD logic to CMOS on a board thats all hardware based.  I will post all information on this blog post as time goes on.  This will not be a complete TM-D710A keyboard adapter, however by providing your own MCU platform you will be able to accomplish the same thing.  My hope is to get this all under the 100ma rating of the 710 8V source to be in line.  The spice run on my initial schematic shows 16ma for this board which will turn the one wire protocol into something a MCU can read.  I’ll also provide a AVR hex file to play with shortly.  If you are interested in building this please let me know by simply posting a comment.  Once I get at least 10 people committed I will order boards.  They will be prototypes and I make no guarantees whatsoever that they will work and you may need some bailing wire and replacement parts so you’ve been warned.  These will very likely be my last run of boards related to this issue as I have something that works already so if you aren’t afraid of SMD and getting your hands dirty post here.  I expect the boards and parts kit be less than $40.00US.

04/21/2011 10:12PM EST

Ok here it is.  Please post if you are interested and how many you want.  Once enough people post, at least 10 boards,  I’ll start contacting those folks and put together an order.  These are prototypes so they may require tinkering.  Basically this has  PWR connections that will work with the 8V on the mic or from 12V.  You will need to make a RJ45 cable to pull out the YELLOW / PIN 8 for the one wire communications.  On the edge of the board there is a pin for each row and column which you can control with your own MCU.



5 Board commitments so far. 5 to go.  I’ll likely refine the design a bit before sending off to have them manufactured but I’ll post the final design prior to ordering boards.

04/25/2011 10:13PM EST

8 Board commitments. 2 more to go.  Here is revision C.  Everything is kitted and ready.  I’ll be contacting those that have committed and place the order after 2 more boards, maybe a few more.  THESE BOARDS WILL BE PROTOTYPES!  THEY WILL TAKE ABOUT A MONTH TO ARRIVE AFTER THE ORDER IS PLACED!!!


04/26/2011   7:00AM EST The last two boards have been committed.  Those of you that have committed I’ll be emailing details to you.  If you plan to get one of these and haven’t committed I’ll need to know sometime early today.

04/27/2011  7:00AM EST Last call for boards!!!!  I’ll be sending out for manufacturing on Monday May 2nd early in the morning. No funds, no board.  I’ve already recieved funds for over 10 boards so Monday morning is the absolute cut off date.  Below is a gerber view of the board, now is the time to ask questions if you are ordering a board.

TM-D710A Keypad Adapter.

04/28/2011 – Few changes on the SO-89 footprints after test fitting parts.  For those that have contacted me boards will be sent to board house on Monday morning.

05/01/2011  The design has went to the board house.  I won’t be adding any more to this order.  For those that ordered boards they should arrive in 3-4 weeks and I will promptly ship them and parts pack when they arrive.  Here is the final gerber view.


Compiling KiCad on Mac OSX

You’ll need to build wxWidgets with this:

./configure –enable-unicode=yes –enable-shared=no –enable-monolithic –with-opengl –with-expat=builtin –enable-aui –with-osx_cocoa –with-macosx-sdk=/Developer/SDKs/MacOSX10.6.sdk/ –prefix=/opt/wxwidgets-svn –enable-universal-binary


And then make KiCad:

cmake ./ -DKICAD_TESTING_VERSION=ON -DCMAKE_INSTALL_PREFIX=/Applications/kicad -DCMAKE_CXX_FLAGS=’-D__ASSERTMACROS__’ -DCMAKE_OSX_ARCHITECTURES=’x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk/ -mmacosx-version-min=10.6′ -DCMAKE_BUILD_TYPE:STRING=’Release’



./configure –enable-unicode=yes –enable-shared=no –enable-monolithic –with-opengl –with-expat=builtin –enable-aui –with-osx_cocoa –with-macosx-sdk=/Developer/SDKs/MacOSX10.6.sdk/ –prefix=/opt/wxwidgets-svn –enable-macosx_arch=x86_64 –enable-debug


cmake ./ -DKICAD_TESTING_VERSION=ON -DCMAKE_INSTALL_PREFIX=/Applications/kicad -DCMAKE_CXX_FLAGS=’-D__ASSERTMACROS__’ -DCMAKE_OSX_ARCHITECTURES=’x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk/ -mmacosx-version-min=10.6′ -DCMAKE_BUILD_TYPE:STRING=’Debug’



AMBE Codec board. 2020 and 3000.

I’ve been working on using DMR in ham radio for some time and found an immediate need for the AMBE codec for both encoding and decoding. Playing with DSTAR i had build a 2020 breakout board and I’ve migrated this design to the 3000 to do the AMBE2 codec.  There doesn’t seem to be much interest in this but if you are please drop me a line.  I’d like to find more uses for this. Right now I’ll be working on an off with a Freeswitch based DMR repeater controller.  Hopefully to allow DSTAR, DMR, and analog systems to be interconnected at some point.