I'm a leader not a follower!

I'm a leader not a follower!
Two Toads I rescued from the road!

Sunday, June 8, 2014

Ford Fiesta ABS Light Stays On

The ABS warning light lit up continuously on my daughters Ford Fiesta Style 2005 plate.

ABS Symbol

After a bit of Googling (other search engines are available) to see what the fault could be and narrow down my search area. I finally got around to taking each wheel off in turn and checking the wheel speed sensors for damage. I found the drivers side front wheel speed sensor's wire insulation nearest the inside of the wheel arch had worn away exposing the copper wires inside, it had also worn away one of the wires. The sensor wire wearing away may have been due to a broken suspension spring that occurred a while before the ABS fault, the spring was replaced a while back. As a test repair I soldered the broken wires of the sensor back together and switched on the ignition but the ABS light stayed on. Disappointed I drove down our private road and after driving about 30 feet the light went out, yeehaa! (this is me happy). Apparently from what I have read the ABS light will stay on even after a sensor repair until the ABS system detects pulses coming in from the sensor after the vehicle is in motion, only then will the light go out.  I ordered and fitted a new sensor cable assembly to replace the temporarily repaired one as I didn't want to take chances with a repair on the ABS system, the ABS light has stayed out ever since.
If you undertake any work, be safe, remember cars are heavy, tools are dangerous if used incorrectly, you are responsible for your own actions.
I bought one of these F-Super Diagnostic USB dongles to read the fault codes and reset the fault on the ABS ECU.
 F-Super Diagnostic Dongle  
I installed the drivers and the software onto my laptop, plugged in the usb. I then plugged in the dongle to the OBD connector on the Fiesta, it is located at the bottom of the Steering column cover under a little flap. The software was run and the fault code read it was indeed signal loss from a wheel sensor. I wish I had this device before, so I knew what I was looking for when trying to fault find.
I also reset the fault code on the ABS ECU so if the error comes back I'll know.

Thursday, May 15, 2014

Arduino Uno Ceramic Resonator

I was using an Arduino Uno to measure the PPS (pulse per second) pin from a GPS module to allow comparison with the PPS from a DS1307 RTC real time clock. I used interrupts 0 and 1 of the Arduino to trigger on rising edges of both PPS pins to trigger a reading from the micros() function and then subtract this reading from a subsequent micros() reading taken on the next rising edge so giving me a measure of the pulse width in microseconds, give or take four microseconds. Apparently the misnamed micros() function cannot make one microsecond measurements. Using this setup I was able to see that the 16MHz clock on the Arduino was out compared to the GPS PPS pin which from the datasheet was accurate to the tens of nano seconds range. The measured error I found was due to the Arduino using a resonator for its system clock, known for not being as accurate a crystal. The strange thing is there is already a crystal on the board for the USB serial chip, probably for accurate baud rates, it is 16MHz the value we need. I removed the resonator for the ATMega328P from the board and made a direct connection from the crystal oscillator output of the USB serial chip to the oscillator input of the ATMega328P. The board can still be programmed and now has a more accurate system clock for my measurements. I wonder if this is something that could be done to the Arduino to save the cost of a resonator. I eventually moved my sketch to a Stellaris Launchpad which has an 80MHz clock and can measure down to one microsecond with its appropriately named  micros() function.

16MHz Resonator removed, center of PCB

16MHz Osc Output of ATMega8U2 connected to ATMeg328P Osc input

Thursday, April 10, 2014

Panasonic DECT Cordless Phone KX-TGA672E with faint LCD

This Panasonic DECT cordless phone developed a fault where the LCD was very faint and adjusting the contrast made no difference. This fault was traced to the flexi-circuit from the LCD to the main printed circuit board of the phone. It was bonded in some way to provide the electrical connection and was not soldered. To fix it I cut up a rubber eraser to the correct size the width of the flexi-circuit and a thickness of (1.5mm). This eraser helped to push down on the flexi-circuit when the white LCD housing was clicked onto the PCB. This fixed the fault and the LCD is now as it should be and the contrast adjust also works. Very annoying fault and a result of cheap manufacture not lasting very long.
Thanks for reading, I hopes this helps someone.

Wednesday, February 5, 2014

DG843GT List dhcpd Clients

I wanted a way of listing connected devices that have been served an IP Address using the command line on my DG843GT ADSL2+ router with DGTeam Firmware. This firmware allows ssh login and the ability to change the noise margin amongst other things.

I began by looking at the link for attached devices on the admin webpage of the router. This URL was examined and the command nbtscan was noticed.

This was tried on the command-line but it didn't seem to do anything , nbtscan --help didn't help either.

I thought it must be something to do with arguments so I tried nbtscan (my routers IP Address) this listed the attached devices so it's a result.

I haven't written a script using expect to get and extract this info automatically yet but it's on my todo list.

Example of the command and its output xx added to anonymise my MAC addresses
 # nbtscan;UNKNOWN;00:xx:83:2D:xx:BA;TORE;00:1F:xx:C8:xx:B5;UNKNOWN;00:1B:xx:07:xx:A3;DEB;D6:56:xx:FE:xx:57;DAD;00:30:xx:46:xx:2E

Tuesday, February 4, 2014

Linux Tinyos example for patching a header file

 I was having problems making a simple program for TinyOS using the command :-

make micaz

The micaz is the target device and can be other devices like iris , telos & tmote etc.

The error I got was:- 

error: variable ‘McuSleepC__atm128PowerBits’ must be const in order to be put into read-only section by means of ‘__attribute__((progmem))’

From reading around the issue is documented here.

The patch is downloaded to the ~/tinyos-main/ directory and it patches the atm128const.h file to prevent the error messages.

The patch is applied using the following command:-

patch -p1  < tinyos-atm128-const-fix.patch

Wednesday, January 29, 2014

Pentalobe Screwdriver Size Modification for the Macbook Air

 Remember that using tools can be hazardous so wear eye protection and proceed with caution , if in doubt don't do it.

I had the annoying problem in that the Pentalobe screws for the Macbook Air I was repairing were too big for the Pentalobe screwdriver I had lying around , it was one supplied in a kit for replacing the LCD on an iPhone. I then realised that the head on this screwdriver has a stretched sort of taper so I basically ground the end of it with a grindstone fitted to my Dremel tool until it fitted the screw-head , testing the fit as I went. Job done , although the modified tool will now no longer fit the iPhone , that's not too much of a problem because iPhone replacement LCD's usually come with the tools required to do the job.

Ground Down Pentalobe

Tuesday, November 12, 2013

Wireless Charging on a Star S7189 Mobile Phone

Warning: while soldering be careful of solder fumes, wear eye protection and don't burn yourself.  Note that charging batteries can be dangerous especially Li-Ion but the work detailed here means we are effectively generating our own internal 5V supply in the phone and connecting this directly to the USB power connections as they come into the phone. It is the equivalent of connecting a micro USB cable to the phone from a 5V USB charger, only its wireless. You have been warned and I am not responsible for your actions.

S7189 Display

This S7189 quad-core Android phone from Star was pretty cheap around £100 and it worked well.  I found the front facing camera was not the best, but for the price I can live with it. Screen was also pretty good with a reasonable viewing angle. It was also pretty slick running any Apps I downloaded from Play with no signs of lagging.

Palm Internal Charging Circuit
I wanted to add wireless charging to the S7189 so I didn't have to keep plugging the charger into the micro USB connector. I noticed on HackaDay that some people had added wireless charging to their mobile phone , this is what I wanted. So I ordered a wireless Palm case back from Ebay for £3.

Palm Back Cover

I then using scissors cut out out the area of plastic bounded by the Plastic label with Palm on it. This was to allow one to be able to peel off the label more easily from inside the case. I then stuck the label on some plastic film (after removing the circuit board, coil and metal discs) to preserve its stickiness.  

Circuit Cut Out of Plastic Cover
The coil and circuit board were removed from the old Palm cover by soaking in a plastic tub of Methylated Spirits for a few hours to soften the double-side sticky tape holding circuit and coil onto the plastic cover.

Sticky Cover Preserved

Stuck to Clear Film

S7189 Back with Cover Removed

The S7189 internal back cover is removed (quite a few small black screws) exposing the Circuit board. I plugged in a Micro-USB adapter to find out where the center conductor was connected to on the Power PCB at the lower part of the phone using a multimeter set to continuity tone check. Ground was the metal tabs of the Micro-USB connector. I used Kapton tape to insulate the sticky copper foil I was using to route out power to the top of the back cover.

Ground Connection

I then soldered flexible tinned insulated wire between the two Copper tabs next to battery, taking care not to overheat the plastic.

Routed Copper Tape

Palm Charge Circuit Added to S7189 Back Case
The removed Palm charge circuit was stuck to the middle of the S7189 back cover using its original sticky cover. Of the two small square gold connectors to the left of the Kapton tape the Lower one is the +5V the upper one is 0V or Ground. To be sure check the output yourself with a multi-meter to ensure you have the correct polarity before connecting it to your valuable phone.

Phone Placed on Charger

Phone Now Charging

The S7189 is now able to be charged either by using the Micro-USB or wirelessly via the Palm Touchstone charger. Note: don't use both at the same time or there could be overcharging problems with subsequent overheating and fire from the battery and circuit boards.