Posts on Murli Shenoy

Project Idea: Low power Eink display

Sun, 31 Dec 2017 00:48:03 +0000

I’ve had this idea in mind for a while, an E-paper display that is connected to the internet.

In this blog post, I want to freeze the high-level idea and the project execution plan. Hacker/maker Extraordinaire Sprite_TM has done something before on similar lines. I’m planning to build my own version from scratch while adding some new features

I use a combination of physical sticky notes, along with the reminders and notes app on my Apple devices for improving my productivity at work and at home. I feel that it would be a great idea if could somehow combine these three tools into one device, and this is the first step towards it. Here’s a block diagram of my Idea.

The ‘Magic’ behind Fast Charging

Mon, 04 Sep 2017 06:57:34 +0000

The Idea for this post struck me on a hot summer day here in California, it was a 100F outside and my phone mounted on the car dashboard wouldn’t charge as fast(like 1% in like 30 minutes) although the phone indicated that it was in fast charge mode and I could not see any other issues with the charger or the charging cable, maybe the heat was affecting the charge rate?, I had to find out for myself.

Fun with capacitive touch and low power circuit design

Sun, 16 Oct 2016 01:42:48 +0000

Recently, I built a touch activated LED toy based on the Attiny85V from Microchip (née Atmel). The schematic is shown below

I got the PCBs made from every hobbyist’s favorite PCB manufacturer OSHpark. On the surface, the project seemed pretty simple. It gave me an opportunity to work on touch sensors and learn their functioning and implementation. I decided to go with an external touch sense solution(MTCH102 from Microchip as well), as I had plenty of board space to spare and, the it wouldn’t add much cost to the BOM. Also it would save me a lot of development time as implementing a robust power efficient capacitive touch library could be an interesting project in itself!

Hiking: Visit to Alamere Falls

Mon, 01 Aug 2016 00:47:47 +0000

Yesterday I visited Alamere Falls, near Bolinas,CA.

We started at the Palomarin Trailhead (there’s plenty of parking there, it being peak season though we had a hard time finding parking)

It’s a rather long hike (8 mi+)but large sections of trail have good tree cover and it was very foggy when we visited. do remember to pack as much water as you can and some energy bars.Note that there’s no clear sign or marking indicating the trail that leads to the waterfall. I suspect that this might be due to the fact that trail is quite dangerous and steep, and the authorities don’t want people to go there. I used the offline maps feature in here maps to find my way.

Pasta sauce hack: How to make creamy tomato pasta the easy way.

Sun, 24 Jul 2016 23:09:29 +0000

It was a lazy Sunday afternoon, and I was craving something that’s tasty, but not too difficult to make and pasta sounded like a good idea. I really love creamy Alfredo sauce, but i had no parmesan cheese on hand. I also like tomato pasta sauce, but when made fresh. I really hate the taste of store bought pasta sauces, they are way too sour and leave a weird aftertaste. But these sauces are super convenient, so I always have them in stock.

Working on a “secret” project, and fighting feature creep!

Thu, 16 Jun 2016 08:10:09 +0000

I started work on a new design, I have long had a desire to create a “product” from scratch using minimal off-the-shelf stuff. This design should help me achieve that goal, and help me learn project management(albeit on a micro scale! :P). Last year I spent some time on an esp8266 based design, new ideas got added to the design midway and a couple iterations later, i have OSHpark purple “art”. FEATURE CREEP, as it’s called, its very hard to fight off.

Quick post: Logitech Mx MASTER Fix

Sun, 05 Jun 2016 21:16:12 +0000

Saw this post on hackaday and decided to work on fixing my own Mx Master which had the infamous scroll wheel issue. I could not toggle between the scroll modes of the mouse. The feature stopped working the very next day i started using the mouse. It seems to be a design issue on logitech’s part. But its a quick and simple fix, check the hackaday post above for more info.

Electronics Inside a Philips Sonicare Electric toothbrush

Fri, 15 Jan 2016 08:10:38 +0000

Today a coworker of mine gave me his old Philips Sonicare toothbrush. He said it had stopped charging and would no longer work. That was a good opportunity for a tear down 😉

Lets see what makes this baby chooch….(As the great man himself said https://www.youtube.com/watch?v=lA0kiYqyBmo)

There’s very little to this device. it seems like there’s just a micro controller running the show, like every other product. (there’s more horsepower in a toothbrush these days than an a 50 year old Supercomputer!) it probably does the following tasks( my guesstimate)

Murli’s blog has a new home

Mon, 07 Dec 2015 02:46:50 +0000

Last weekend over thanksgiving, I finally found some time to move over my blog to a custom hosted solution over from the old one. I now have a custom WordPress install(this might change soon, as I’m looking at other options, which are more efficient like jekyll ). The blog should now be snappier, also i’m planning to add a few bells and whistles on the backend (git server, host some files etc). On the hardware front, I am currently working on the ESP8266 on adding an Epaper display and a few custom sensors. I’m using a rather interesting and firmware framework called SMING, which is an interesting hybrid between the Arduino framework and native GCC. Sming I feel is still rather nascent, but the developers are working hard on refining it. I plan to finish the e paper display interface this week, and then I can go ahead with finishing the project, something that looks more like a product than a quick hack. I’ve had a few stumbling blocks along the way, which i have put them aside for now.

Raspberry Pi laptop

Fri, 17 Jan 2014 02:14:26 +0000

Recently, I got a used Atrix 4g lapdock for 30 bucks off of craigslist. It was a really good deal for a device that packs a USB hub, a 10+ inch LCD a keyboard, a trackpad and also a 10000mAh battery. Supply it with a processor and it can be a full fledged laptop computer. My atrix 2 worked fine with the lapdock. I used it a lot for watching youtube videos and for PDFs.

Teardown of a 13 year old canon digital camera.

Mon, 06 Jan 2014 04:45:35 +0000

canon camera teardown, a set on Flickr.

A couple weeks ago, at work I found a digital camera that was thrown away in the recycle bin, it had a broken LCD and everything else seems to be in good shape. It was a 2.1 Megapixel Shooter so i figured it must really old. On googling I found that it was launched in 2001 and one of the smallest digital cameras of its time. and cost like $600 US! these days you can get a decent DSLR for that price. Check out the review of this device here!

Restoring the Windows Boot Partition…..

Sun, 25 Aug 2013 08:14:19 +0000

I have a Dual Boot boot system Running Ubuntu 12.04(LTS) and Windows & Home Premium(x64).

The other day i was booted into ubuntu and had to use gparted to partition and format a flash drive to use with my Pogoplug-B01. And i by-mistake formatted the windows boot partition . Oops. I restarted my system and could not boot into windows! For me Windows is like a necessary Evil . Its where all my games reside! All for the other programming related stuff i use ubuntu. So i needed to get the windows partition up and running.

Playing with the UART on the TI Stellaris Launchpad.

Wed, 12 Jun 2013 10:12:45 +0000

I just started playing around with the TI Stellaris Launchpad a couple of days ago.

The Launchpad is a pretty powerful little dev board. It has ARM Cortex-M4F core at it heart. The really awesome thing is that there’s a Full fledged debugger built-in which makes it a really good board to start with ARM micros.

I was fiddling with the UART trying to setup two way communication with the micro. so i started out with the uart_echo project included in the Stellarisware bundle.

Maker Faire 2013

Sun, 19 May 2013 08:49:04 +0000

Maker Faire 2013, a set on Flickr.

The Bay Area Maker Faire 2013 Day 1

Philips SHH7810 In-ear headset for Mobile Phone review

Fri, 10 Aug 2012 05:41:03 +0000

A couple of days ago i received in my order of Philips SHH7810 in-ear headset from Flipkart.com. They delivered it in like 2 days as promised. I love their service and sometimes the price is also very reasonable as compare to brick-and-mortar stores,which was true in this case.I got it for 985 INR,which i think was pretty reasonable.

The SHH7810 in my opinion is one of the cheapest and quality headsets with inline microphone that money can buy,I had done some research prior to finalizing this one, i coudn’t find any decent brand(aka sennheiser,skullcandy,sony,etc) earphones with inline mic and call.answer button,there was one from skullcandy around the 1k INR range but i was using the skullcandy ink’d for the past 8 months which was very similiar,I wanted some change and this had to be it.

Motorola Atrix2 reviewed

Sun, 29 Apr 2012 06:24:38 +0000

Motorola launched the atrix 2 in india late last month. Almost six months after they launched it in the US.

It seemed like a good vfm phone given the market price of around 22,000 INR and the many positive reviews all around the internet made it seem like an awesome buy!!!

So i thought i should check it out.I ordered it,from probably india’s answer to amazon flipkart. it arrived 3 days post order. Packed snuggly in couple of layers of bubble wrap which i enjoyed popping! :P.

Dangerous Prototypes Bus Blaster Build

Thu, 12 Apr 2012 18:36:56 +0000

I had Received a free Coupon from Dangerous Prototypes as a part of their Free PCBs Contest.I chose to get the Bus Blaster PCB. Since i was really needed a JTAG debugger my lpc1768 blueboard. Just Completed the Build. Check it out! Soldered the FT2232 using the drag soldering method.Had to remove some stubborn solder bridges formed during the soldering of the fine pitch QFP using a razor blade! Thanks Ian and Dangerous Prototypes! 🙂

Bluetooth Controlled RGB LED strip

Sun, 25 Dec 2011 07:44:03 +0000

RGB LED strips such as this are available for a low price.They are generally bundled with a IR controller and a power supply to power the LEDs and to change the color ,display various colour sequences etc.The IR Receiver is similiar to those used in TV and requires line-of-sight for reliable operation . I wanted the strip to be Controllable via a PC or a Mobile Phone.So I decided to make my own RGB LED strip Controller and to enable wireless control i used Bluetooth technology.The device can be controlled using a PC or a mobile phone with Bluetooth having a suitable graphical user interface.

Adding Bluetooth To your Microcontroller projects

Wed, 26 Oct 2011 18:36:49 +0000

Bluetooth has become Ubiqutios these days Bluetooth Wireless technology is present is Most mobile phones today as well as in laptops and in desktop PCs.And If your PC or laptop doesn’t have it then you can get a Bluetooth USB dongle for cheap(like 2-3$ )!

Wouldn’t it be interesting if your mobile phones /PCs could talk to your Micro-controller Projects??

Lets find out how to add Bluetooth capability easily to your existing Micro-controller projects with out many hardware or software changes.

LPC1768 – Sending a Byte output to a port

Tue, 11 Oct 2011 20:11:53 +0000

Just a Simple code snippet that allows you to send a byte over a 8-bit wide parallel bus when using 32 bit devices such as those based on the ARM architecture.

While programming AVRs this usually would suffice to send a BYTE over a parallel 8-bit wide port.Here’s an avr-gcc example

PORTC = data;

But with the a 32-bit microcontroller For example the LPC1768 from NXP.

Each port is 32 bits wide and in order to send a byte over an 8-bit section of the 32 bit wide ports

Steps to include Indian Rupee Symbol Font in MS word applications

Thu, 22 Jul 2010 10:14:28 +0000

Recently the indian rupee joined the elite league of currencies that have their own unique symbol. The symbol is a combination of the devanagri ‘ra’ and also symbolises the roman letter R. the two stokes signifies the tricolour and the progress of the nation. here’s how u can use it in your emails and word documents.

Given below are the steps to use the new Indian Rupee Symbol as a Font in your word applications:

make a PCB yourself

Tue, 13 Apr 2010 21:10:58 +0000

Making a printed circuit board (PCB).

First cut the copper clad board to size required.
Sand the surface of the board to remove the layer of copper oxide that is formed due to the reaction of the copper with the oxygen in the air.
Once the copper surface is shiny and clean avoid touching the surface of the copper.
Eaglecad or ORCad may be used to design the schematic and the pcb design .
Take a mirror image of the pcb design while using the CAM processor to generate the Gerber files .
The gerber files maybe viewed online at http://www.circuitpeople.com or the .eps file maybe viewed offline using the .eps viewer take a lazer printout of the pcb layout using. this printout will be the mirror image of the actual pcb layout .
Since during the transfer process the mirror image of the actual image will be transferred.
Now cutout the actual PCB layout on the transperency. this will be the toner transfer
.
Lightly wipe the toner layer of the toner transfer with a peice of cloth and the surface of the cleaned copper clad. This will ensure that there is no dust or grime between the toner surface and the copper.
Place the transfer on top of the cleaned copper clad board.
Secure the layout in place with the help of a peice of tape or some glue.
Using a hot clothes iron heat the toner transfer so that the toner layer from the tranfer is transferred onto the copper.(set the iron to the highest temperature possible…usually the cotton settings)
Iron the transperency gently.
Don’t put too much pressure on the clothes iron else the toner will smudge. too little pressure and the toner wont be transferred at all.
Once you think the toner is stuck to the copper turn off the iron. let it cool down to the ambient temperature.
Peel off the transperency if you got it right then you will see that almost all the toner has been transferred to the copper surface.
The toner layer will form the etch resist.
Now the copper clad can be put into the etching tank. ferric chloride maybe used as the etchant. although muriatic acid maybe used too.
Gently ‘move’ the copper clad board through the FeCl3 solution.
Once all the unwanted copper has been removed clean the PCB under running water.
Remove the layer of the toner with some sand paper or a solvent such as acetone.
If the PCB is meant for surface mount components then the PCB might require drilling.
After the drilling is over. tin the copper surface to protect and increase the conductivity of the copper tracks.

References:

Made a Big Muff Pi….check it out…..my guitarist buddies are checking out the stuff!

Fri, 02 Apr 2010 19:52:35 +0000

DIWALI PROJECT – LED luminaire

Sat, 17 Oct 2009 15:58:00 +0000

Happy diwali to all!!!

Last week i was alone at home since my parents had gone out to attend a marriage in mangalore.I was alone at home for about 10 days and had no college since there was our college ‘techfest’.i dont like attending ‘techfests’ on a shoestring budget,like the one in our college!!.there only a few things which fit into my definition of tech there!

So I was alone & bored and to get rid of my boredom and loneliness i wanted to do some fun project.i had a few hundred bucks with me,and i had an old luminaire (called jhoomer in hindi)-it had those bayonet mounted so called ‘zero watt’ incandescent bulbs. I consider incandescents a thing of the past as they are very inefficient and are energy guzzlers-they waste a lot of energy as heat.Infact they generate much more heat than they produce light!!!So i thought that replacing the incandescents with power LEDs which consume lower power and produce much more light.Also the light is much more soothing to the eye.

philips she-9500 reviews

Wed, 16 Sep 2009 12:59:00 +0000

I was desperately in need of a good pair of in-ear earphones for a long time since my JVC FX-33 marshmallows went kaput a few months ago.So I got myself a new philips she-9500 from the tech haven of mumbai aka lamington road for about 750 INR a couple of days ago. I had done quite a bit of research before buying these earphones.Here’s the review.

First of all i’m no hardcore audiophile,but the audio quality is a top priority to me and i can’t bear to hear the bassless music from the silly nokia earphones bundled with my nokia n78.I a huge linkin park fan and i can hear linkin park all day long!!. The philips earphones are very good VFM earphones. The transperent blister package it came in contains the following.

High efficiency portable gadget charger

Fri, 10 Jul 2009 17:47:00 +0000

In my earlier post i had made a gadget charger which could charge your mobile phone,ipod,or other gadgets.It was based on a rather simple chip -the humble 7805. Now lets move a step further and make a more efficient emergency charger. this charger is based on the lt1302 from linear technology. I had got as samples from linear.com samples service two lt1302 ics .the datasheet provided very promising numbers efficiency reaching nearly 87%!! wow!!!!that’s great.That means more charge gets into your gadget.

diy emergency gadget charger

Wed, 08 Jul 2009 08:30:00 +0000

I have a nokia n78.I often use the gps onboard to find my way through the urban jungle of mumbai.The gps is surely a very useful tool for navigation but it tends to suck the battery juice pretty quickly. My phone can give only about 3-4 hrs of continous gps use on a full recharge.I’m a urban explorer kind of a guy so i like getting lost and found in the concrete jungle but that sometimes takes a lot of time.so much time that my battery runs out before my adventure is over!!. and so i decided to make myself a portable mobile charger.

1 watt High Efficiency Power LED lamp

Sun, 05 Jul 2009 14:52:00 +0000

These Days power leds are available very cheap.I had seen a lot of stuff on the net about the “1 watt led” and i fell instantly in love with these beauties!!These babies have a very high lumen per watt output as compared to either incandescent or the flourescent technologies.For the layman this means very high efficiency-you get more bang for your buck.But driving these things may be a bit difficult .

My first Post

Sun, 05 Jul 2009 14:45:00 +0000

This is my first post on this blog.In this blog i plan to record my jouney in the fascinating world of elctronics and microcontrollers.Electronics is my passion and whenever i find spare time i indulge in either making electronics or breaking them. So far i have made as well as opened up a lot of electronics stuffs. From these i have gained a lot of knowledge.I would be recording all the knowledge i learn on electronics on this blog.