Hi all!

Just a note to let you know who is currently judging your excellent work...

We have:

Zhang Paul : Global 8 bit product marketing manager

Laurent Vassort : EMEA distribution Technical Resources Manager

Also, your projects have been passed around the office like wildfire at Freescale!

Don't forget that your vote in the poll is also appreciated, as the engineers at Freescale who are helping with the judging need to know who your favourites are. We hope to be able to announce the winners next week, so stay tuned...

This is my blog entry on what i managed to do with the XL_star kit i received as part of Element14's Summer of Design. Although it is a few days past the deadline, i thought it will be good to share my experience with Xl_star board

i registered for 'Summer of Design' without any projects in mind. The plan was to decide if i receive the kit.
On reading about the XL_star, it struck to me that the kit with its accelerometer is an excellent platform to do relative position control of objects. The first project that came into my mind was RC car, for my nephew to play with
There was some confusion regarding whether i would be receiving the kit or not. By the time the kit arrived(without any email notification) i had lost interest and got busy with my research work. Still the desire was there to do some project with XL_star board. But taking my time and financial limitations into consideration, i decided not to do any hardware work.
While going through discussions in XL_star group of element14, i saw a post enquiring about XL_star as usb hid mouse. Considering my original idea of using XL_star as a position control device, i decided to implement usb hid mouse on XL_star.

The plan is to use the three buttons for mouse clicks and tilt of the board(in landscape) for moving mouse pointer as illustrated below:

The leds will glow to indicate the direction of movement of the mouse

I first downloaded the usb stack from the following webpage:
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MEDICALUSB&fpsp=1&tab=Design_Tools_Tab
Now the task was to combine the XL_star demo code with the usb hid example from the stack. Code to emulate usb mouse was added to the orientation demo. On compiling i got 'out of memory' error. On analyzing i found that floating point library was using more than 55K, which together with the usb stack resulted in memory usage of more than 64K.
i was about to give up on the project(i was working on the project during night, as i was busy with my research during day time). But suddenly it occurred to me that the microcontroller in XL_star had 128K of flash. Now the task was to find out the missing memory. On going through all files in the project directory, i came across the 'prm' file. This file contained the memory map and usage of the memory. I modified this file to use the flash, but i got compilation error. On further digging i found it was a problem with memory model setting of the project. I created a new project with banked memory model, and copied the new project's 'prm' file to the original. There was linking error now, which was due to the floating point library not being bank compatible. I replaced the library with the correct one, and the project finally compiled properly. After some fine tuning in the mouse code, i was able to make XL_star into a reasonable usb hid compatible mouse. I then removed most of the unused code from the original XL_star demo project, for better memory usage.

All are welcome to download and try out the code.
For converting this project into a RC car controller , all i have to do is to replace the usb API call with custom code to send data serially to an RF module. I might try this out when i have more time and resources

Working with the freescale codewarrior IDE was a real pain in the neck. For example, if we change the memory map model or the floating point format through compiler settings, it would not automatically select the appropriate library. We have to manually search and replace the library.

Suggestions for future Summer of Design
  Make it a three month event - Concept, Design and Engineering
  A week before the concept phase, the platform should be announced and project proposals invited. One month should be given for people to decide on the project and blog about the same. Depending on the blog entries a subset should be selected for the design phase. This group should be given the development kits/IDEs to start their design.
During the design phase, the various groups will go about designing the software algorithm and hardware. The blogs will be regularly updated. At the end of this phase a subset from the entries will be chosen for the engineering phase depending on their progress. This group will be given further hardware resources to continue their project
During the engineering phase each group will do the final implementation of their projects. At the end of this phase winners will be chosen depending on the overall progress.
All groups can continue till the final phase, but those who are not selected for the further stages should meet the expenses on their own.

DESIGNERS:-      1)Jayneil Dalal

                     2)Samarth Shah

BACKGROUND:- We are currently pursuing our bachelor's degree with Electronics and Communication as major from Nirma University, India.

MOTIVATION:- A month back we visited an old age home(where old people with no one to take care of them live). There were a lot of elderly people sitting at their places, not moving much. The heat was insane, driving us crazy as the FAN was turned OFF. Upon interaction with them we found out that many of them were disabled while others found the task of going to the other end of the room just to turn ON the fan too tiring and their health did not permit to do the same. That is when we decided we would make a device which will enable these elderly people to control the electronic devices around them wirelessly.

AIM:- To develop an embedded system which would control the electronic devices around the house wirelessly via different hand gestures. Moving the hand towards right would turn ON the light while moving it towards left would turn OFF the light and so on..

HARDWARE REQUIRED: - XL_STAR BOARD(x2), Relays(x5). PCB(x1), IR LED(x1), TSOP(x1), Hookup wires, Breadboard.

1) XL_STAR Board:

2)Relay: (5 PIN POWER RELAY for AC based applications)

3)PCB:

4)IR LED

5)TSOP (aka IR RECEIVER)

6)Hook up wires

7)Breadboard

SOFTWARE REQUIRED: - Eagle, CodeWarrior Studio

1)Eagle (http://www.cadsoftusa.com/downloads/?language=en )

2)Codewarrior Studio

Construction:- All the wired connections of the different electronic appliances are connected to the PCB containing relays. There will be one relay for each electronic appliance.

The header pin(p) of relay is connected to the +ve pin or live pin of AC electronic appliance. The other pin of electronic applicance is grounded. NC pin is left open. NO pin is connected to AC power supply. The terminal pins of relay are connected to the pins of XL star board. This XL star board will act as the RECEIVER and will have TSOP has IR receiver.

Now the other XL star board will be mounted on hand of user and will act as TX using IR led as transmitter. So depending upon different user hand movement , corresponding code will be transmitted to RECEIVER XL star board.

Please see the "Block_diag.pdf" which has the diagram to illustrate the same: (the figure is very bad, please pardon me as I don't know any other software to do the same but will update it soon)

Working:-

Note:- To understand the working of the relay(electronic switch) , see the attached file "Relay_work.pdf"

1)The user makes a gesture via the XL star board(TX) by moving it in a particular direction.

2)Now a specific code for that gesture is already made. It is then amplitude modulated and sent to the the XL star board(RX) via IR led.

3)The RX board takes corresponding action for the received code , i.e. , give high ouptut(1) at the desired application control pin.

4)This will trigger the relay of the desired application. Hence the required application will turn ON.

Connection Diagram: -

Concepts: - This section will brief you through some of the basic concepts required for carrying out this project on your own. We strongly recommend that you go through it.

                  1)Electrical wiring, sockets used in AC applications.

                        http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

Note:- I will upload the PCB schematic ASAP..

I have been working on a lighting project for my entry project, but some parts I ordered for it have been delayed (I hate UPS), so while I wait for my High power LEDs to arrive, I thought I may start a new small and more simple project in the hopes of completing it Before the LEDs arrive.

Small Digitally adjusted Linear Bench Power supply

By Zeta-UNI

Motivation

I hate my current Bench Power supply. It uses a mechanical potentiometer to adjust the voltage, so the resolution depends on the skill of the user (a.k.a. me). However, this skill changes day by day or even along the day. For example, when you are fresh in the morning you might be able to adjust it precisely. But it might be a real pain to precisely set the desired voltage after a long day at school/work, late at night or after having had some cups of coffee. For this same reason the adjustment is not repeatable.

Also, it has a lot of features I never use, but it lacks a feature that would make my life so much easier: “Allowing a Desktop or laptop computer to set the desired voltage”. If it had this feature, I would be able to write a small script that would set the voltage of the power supply, wait until the voltage stabilizes, read what an attached measurement instrument senses then increase or decrease the voltage and repeat the process. This would probe to be useful, for example, when determining at which level a device stops working reliably like when you are using a battery to power the device.

Unfortunately, commercial Bench Power supplies that can be adjusted digitally are really expensive and out of my budget, so I set to build one on my own.

Requirements and Design Idea

At first, I thought about porting one of the Digital DC Power supply that have their sources freely available on the net like the one on tuxgraphics.org ( http://tuxgraphics.org/electronics/200707/bench-power-supply-unit.shtml ), but the design is too noisy. If anyone is to port that code to the HCS08mm, I would like to say that the HCS08MM MCU on the XL_STAR board is actually a better fit for this application than the MCU used by tuxgraphics because the S08MM has all the components required integrated in the IC, and it would make a truly one chip solution rather than requiring separate ICs for ADC, DAC and even a separate module for USB.

My DC requirements are quite modest: 700mA continuous current and 1.8v to 5v low noise regulated output range. I rarely (if ever) need and adjustable current source. So I decided to use the combination of an adjustable Low dropout linear regulator, a digital potentiometer for the adjustment, character LCD and, to make things fancy, capacitive touch sensing controls.

The workflow

Since the HCS08MM MCU on the XL_STAR is too powerful for this application, the idea is to develop the software on CodeWarrior using the XL_STAR board as the target hardware. Build small modules for capacitive touch controls and digital pot + regulator to connect to the XL_STAR board. Build load and debug the software. Then, when everything is working properly, use the “Change Target” feature on CodeWarrior to set the target to a cheaper HCS08JS MCU. Use CADSoft Eagle to laydown a PCB board for all the components on the project, calibrate the touch electrodes, use the XL_STAR as a BDM to program the S08JS on the final board. This will allow us to trade a £6.04 MCU (S08MM) for a £1.90 MCU (S08JS) in a easy to solder SOIC package and let us use the XL_Star board for other projects. The final step is to test the device and enjoy touch sensing madness.

Design specifications and features

• Regulated Voltage output range:   1.5v  to  5v
• Adjustable increment:  0.1V
• Precision:  2%
• Max current:   1A
• Conectivity:  USB interface
• Interface: Touch sensing interface
• Display: Character LCD

Software Tools and libraries

• CodeWarrior for Microcontrollers v10.1 ; IDE for all of our managing, building and debugging project needs.
• ProcessorExpert module included in CodeWarrior; a really useful tool that makes your life easier and speeds project development (more on this later).
• TSS, Freescale Touch Sensing Software library v2.5; it’s a Software library that turns any HCS08 MCU into a Touch Sensing capable device.
• Freescale USB Stack v3.1, a royalty free stack for USB communications.
• D4CD AN4263_SW Modification of eGUI, Freescale embedded Graphic User Interface library, to support Character LCDs. I would like to use this library but if the USB stack eats all the Flash + ram on the JS16 I’m going to have to use a simpler approach with less overhead.

Processor Expert is your friend

As mentioned before, Processor Expert is a tool on CodeWarrior. It allows you to configure the core and periphetals in an organized GUI-like interface and automatically generates configuration code. It also generates convenient functions for manipulating the different modules on a MCU.

For people new to HCS08 architecture like me, it gives us a head start to project development because it automatically detects the valid values for any given property and tell us when a certain feature is not present or not configured properly for our target MCU. It also includes a detailed description of every property, so we learn along the way the internals of the MCU.

For advanced users, and novice users alike, it simplifies project development because it generates code and functions and exposes simple interfaces to complex periphetals and speeds time to market.

I will be using Processor Expert (PE) not only to configure the core but also to configure and manage the communication interface with the digital pot (I2C or SPI). Furthermore, the TSS library includes a PE module, so I’ll be using PE for the Touch Sensing interface too. I would like to use PE for the USB interface, but, unfortunately, CW Special Edition only includes the USB configuration module. I would need the CW Standard Edition to fully use USB PE module.

Using PE, my XL_STAR board and Freescale’s libraries, I’m hopping I can manage to complete the project in 4 days worth of work, its probably going to take longer to write this blog than it will take to actually write code xD.

Update 09.05.2011 PART II

It's being harder than expected to find some enought time to finish the project. I'll do my best to finish on time. Some math and device selection on this Update

Low Dropout Linear Regulator Device Selection

The requirements ask for 1.5v to 5v output voltage and 1A output current. So, I didn’t think much and choose the MIC29152WT from Micrel. The MIC29152WT offers 1.5A minimum guaranteed output current, programmable output from 1.24v to 25v, 220mv dropout voltage at 750mA (350mV at 1.5A) with ΔVout=-1%, TO-220 Package, 40nA Adj current and a logic compatible Enable pin. At £4 per unit at single quantity it’s a good fit for the application.

Micrel was kind to send me some samples of MIC39102BM that has basically the same characteristics as MIC29152WT but in a Power SOIC Package that limits power dissipation so I’ll be using MIC39102BM for development and be limited to small loads until I can get some MIC29152WT.

The down side of the MIC29152WT (and MIC39102YM) is that it requires 5mA (10mA for MIC39102YM) minimum load current to maintain stability. This means that since the load will vary widely from 0A when no load is attached to 1A at full load, we will need to include a small load that will have to draw at least 5mA at 1.5v.

Features:

• Product Page: http://www.micrel.com/page.do?page=/product-info/products/mic29150.shtml
• Datasheet http://www.micrel.com/_PDF/mic29150.pdf
• High current capability
• MIC29150/29151/29152/29153     1.5A
• Low-dropout voltage
• Low ground current
• Accurate 1% guaranteed tolerance
• Extremely fast transient response
• Reverse-battery and Load Dump protection
• Zero-current shutdown mode (5-pin versions)
• Error flag signals output out-of-regulation (5-pin versions)
• Also characterized for smaller loads with industry-leading performance specifications
• Fixed voltage and adjustable versions

Note: I've chosen the MIC29152WT Regulator, but anyone who is to replicate this project can choose to use any other device that fits the application. As a consequence, it will be necessary to adjust the values of the rest of the design.

Defining Circuit Elements

From the datasheet we can get the output formula

Where R1 and R2 are defined according to this application example.

We may be tempted to replace R1 + R2 with the Digital pot as a voltage divider with the wiper pin connected to ADJ, but if we do it Vout ends up depending on 1/Rw rather than being lineal. Something similar happens if we replace R2. Therefore, it’s necessary to replace R1 with the digital pot configured as a variable resistor or Rheostat (Rw).

.

After taking a look at Datasheets of several Digital Potentiometers, I noticed that none of their pins should be driven with a voltage above V_DD. Some digital pots may allow us to connect higher voltages to H, W and L but it will be necessary to add a separate Dual supply. This would add more components and complexity to the Design than necessary.

Since I’ll be using a V_DD=5V and I want 5V output, it will be necessary to add a resistor before the pot. This way the H pin will never be exposed to a voltage above V_DD, but it comes at the expense of increasing the minimal V_out=1.240V that can be obtained from the regulator.

Determining the number of steps of the potentiometer

From the specs:

• Vout_max = 5
• Vout_min = 1.5
• Vout_max – Vout_min = 3.5

I would like to have an increment of 0.02v for every step of the potentiometer. This way, I can get the required 0.1v increment in Vout every 5 steps and leave room for software calibration with a precision close to 0.02v to make up for component tolerance.

Therefore, if N is the required number of steps

A potentiometer with at least 176 steps is required. The closest standard pot has a resolution of 8 bits or 256 steps so the potentiometer selected will have N=256 steps.

Probably the most exiting part: The Maths

I have to determine the relationship between R1, R2 and Rw to select the right Digital Potentiometer and pasives.

The output equation from the Datasheet and the schematic

Determining R1_max

For Rw = 0 then Vout =Vout_min

Therefore,

R1 depends on R2.

Determining R2

From  (1)

Where ∆V_out =0.02 is the increment of V_out for every step and ∆Rw is the increment of the resistance of the pot on every step.

But

Where R_H-L is the end to end Resistance of the potentiometer and N is its total number of steps (N=256).

In case you are wondering why ∆R_w =R_H-L/N-1 and not ∆R_w =R_H-L/N you can find a good explanation at http://pdfserv.maxim-ic.com/en/an/AN4288.pdf

Then

I’ll use the DS1805Z-010+; it is a Volatile Memory Digital Potentiometer with R_H-L =10 KΩ, I2C interface, Iw_max = 1mA and more importantly a hand solderable SOIC package. (I wish I could use MAX5417 but it comes in TDFN package, it has the advantage of having non-Volatile memory to load saved adjustments on power-on). Therefore, R₂ = 2.43 KΩ.

Then I set R₁=301Ω

Components Selected:

• Voltage Regulator:  MIC29152WT
• Digital Potentiometer:  DS1805Z-010+;
• R1 = 301 Ω 1%
• R2 = 2.43 KΩ 1%

Thats all for this update. I hope I haven't bored you too much with the math stuff but I wanted to include enough detail so anyone can replicate the project with diferent components.

Now that I have the components selected I can build the Touch and Digital Pot modules to connect to the XL_STAR

Update III

Change of plans

At first, I wanted to use Freescale’s TSS for Touch Sensing functionality, but I found 2 problems:

1. Since the S08JS16 has only 20 pins, only 12 can be used as I/O because the rest are used for Power, XTAL and USB. I needed 2 pins for I2C, 6 for LCD, 1 to enable/disable the regulator.  So I was left with only 3 pins for Buttons (and I was missing 1 for USB connection detection).
2. It was almost impossible to achieve good SNR for the signals from the Touch pads. Parasitic capacitance was too high, mostly because of the pinheads I used as connectors and the long and wide traces of the PCB. Unfortunately, the PCB fabrication method I’m using (Home etching xD) won’t allow me to go lower than 10mill traces and 25mill clearance.

So I decided to change plans and instead of using TSS I’m going to use a discrete Touch sensor IC. This is against my non declared goal of a design with the lowest possible number of chips but the alternative would have been to find a better suited connector (which involves a lot of time testing different connectors), change the final target chip to a JM32 in QFP (too many and too small legs) and have the PCB manufactured by a professional fab house that would mean long lead times and/or high cost.

I have decided to use a CY8C201xx CapSense sensor. The SO package of the CY8C201xxs is a good reason to use it in DIY projects instead of its competitors. Furthermore, the CY8C201xx is an I2C device. Therefore, the pins to control it would be the same pins used to control the Digital potentiometer.

Designing the modules

I used Cadsoft Eagle to design the schematic. Unfortunately, I couldn’t find any of the ICs needed in the parts library so I had to make them myself. This has been the first time I’ve ever had to make a custom part for eagle, so this was a good learning experience. I have attached the library file with the custom parts (and some garbage parts I made while learning, still don’t know how to remove them from the file xD) I hope you can take a look at them and tell me what mistakes I made.

With the parts ready I set to design the module

Building the schematic was strait forward. I just followed the datasheets. But I forgot the input capacitors (that would explain latter the bad transient response I was getting >_<). With the schematic ready it was time to design the board layout.

The datasheet for the CapSense parts calls for a 2 sided board, but I stuffed everything on the same side for easy of fabrication of this prototype. A small mistake in the pin assignment of one of the parts that I discovered only when the board was fully routed lead me to introduce a couple of jumper wires (I didn’t want to route it all again).

This is the module ready to be populated.

That’s all on this update. I’m hopping to have the source code ready the next time.

Hi all,

For my entry into the contest, I decided to create a "Crazy Countdown Timer", which emulates the cheesy time bombs often used in movies - In this case, the hero of the movie has to choose which wire to cut (red, yellow, or blue?), without bumping it too much and setting off the motion detector.

And before you start dialing the authorities on me, please know that my motivation to build this was the stash of clock displays in my electronics box

Not sure if my blog posts automatically notify everyone or not, so here is a link to it which has all of the details, pictures, and full source code.

http://www.element14.com/community/people/ntewinkel/blog/2011/08/30/the-crazy-countdown-timer-is-complete

Next I need to figure out how to post my video

So that's my project submission for this contest!

I suppose I could arts and crafts it up to make it look more authentic, but dunno if I'll have enough time to make that happen soon enough.

Cheers,

-Nico

Im working hard with POV device code. The main block of application will be look like:

I write (sometimes copy and paste ) code, but have problem with communication via IIC with sensor. Some nice examples of source code i found in "AN4075.pdf" http://cache.freescale.com/files/sensors/doc/app_note/AN4076.pdf?fpsp=1&WT_TYPE=Application%20Notes&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation

and datasheet for sesnsor. I will fight more with sensor tomorow

Hello Everyone!

As we approach over 150 registered members and with over 45 different applications active on the challenge we set for the Summer of Design, we shared your collective success with our partners at Freescale.

‘This is a great start to evolving the future engineering leaders – we are amazed by what all our innovative minds are achieving collaboratively and are looking forward to the next great application for the Board XL_Star!’ commented Andy Mastronardi, Director at Freescale University Programs.

And Andy knows when he spots innovation as the champion of many successful international programs that Freescale runs. Along with Andy and his team, we are thrilled to announce that next week onwards, we will be opening up our next phase – this is where you all can review, vote and the rest of the community will help pour in there expertise through a polling leader board. Each week we will publish the top 10 applications as you progress your designs. For this, we hope to set some ground rules – as you are the experts here, I would appreciate your views:

Ground rules

1. Graceful professionalism. We have a lot to learn from each other. When the leader boards open, please feel free to comment, course correct and appreciate the applications. If you course-correct, please be respectful and constructive – that is much more fun.
2. If you come across a technical issue – feel free to raise it with our experts: Joe, Gordan and Roy can help offer advice
3. There will be surprises each week and we hope to also source a guest expert to source their favourite Top 5 apart from the public vote. Mystery guests may choose to announce themselves only at the time that fortnightly chart closes
4. If you don’t make it for the first week: remember, this is a fortnightly chart and you can be in the Top 5 very soon
5. Help each other – real innovation happens when we all work together to not instantly perfect but adopt, adapt and improve!

We keep this simple. For you to succeed in this, there is a simple tips –

1.  Keep sharing your design progress with your blog. Some of you are building a great portfolio of what your application serves, what your process is and how you are getting along. If you have it all mapped out, give us an idea of how you are getting along (a status bar for example might be a good way to convey it, or simply end your blog post with what may be coming up next!)

2.  Keep pulsing your friends and colleagues – spread the word about your application! Do point out to your network if they are not accustomed to working in English language they can view the material in any language using ‘google translate’ tool on the top right hand side. One of the simple ways to spread the word is even your status update here on element14, on facebook or tweet about it drawing your own following: you can add @element14 within your update.

3.  Video is king: Take a leaf from our element14 superstar – Ben Heck himself: along with your blog, you can also very simply upload your videos on the application demo on element14. Don’t worry if its not fully picture perfect for youtube’s wider broadcast, but you can even choose the best video clips to piece it together for your final broadcast. Your own debut!

4.  Ask for opinions at the end of your blogs or videos – some of you are already doing that and is driving excellent feedback from many experts on the community

5.  Remember - you are winning anyway! You would have noticed the small badges that have appeared on your profile – you are already earning points on your interaction with the community here: check out the details here on what these means

Till soon and happy designing! *Watch this space!*