Archive for May 2014

[GSoC Daily Log]: Its Alive!

Saturday, 31st may 2014:

  • Fixed the schematic for feedback circuit of ADP3334 adjustable o/p LDO IC for the line PD and VD [Github Push]
  • PCB Repairing/Fixing required for correcting the Power supply’s feedback circuit.
    • PD:
      • 1 Trace cut
      • 1 147k resistor removed and resoldered 180 degrees
      • 2 wire soldering fixes
    • VD:
      • 2 Trace cuts
      • 1 147k resistor removed and resoldered 180 degrees
      • 3 wire soldering
  • Connecting PCB to power supply:
    • It works! PCB Fix succeeded!
    • PD: 1.818V, Fine
    • VD: 1.818V, Fine
    • OVDD: 3.3V, Fine
    • Current: 13.6mA
    • AD9984A also gets warmer very slightly
  • I2C Scan Test: WoW! Board shows up in scan! Its Alive, folks! Hurray! 
    The AD9984A shows up in I2C scan with address as 4C (highlighted red)

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[GSoC Daily Log]: Weird voltages!

Friday, 30th May 2014:

  • Testing PCB for life signs
  • Setting up I2C test setup. I2C scan doesn’t show up AD9984A, whereas shows 2 other PCF8574A test devices on same bus. Something’s wrong.
  • On Powering up the PCB with 5V VCC. Power Supply Problem noticed.
    • OVDD: 3.35, Fine
    • PD: Expected voltage: 1.8V. Actual measured: 0.55-0.58 V, Critically Low
    • VD: Expected voltage: 1.8V. Actual measured:0.39V, Critically Low
  • May be due to OVDD having ADP3303-3V3 whereas PD and VD have ADP3334
  • Assuming problem with 1.8V LDO, Ordered samples for fixed voltage (1.8V) LDOs from TI and Analog Devices (SOIC and SOT23). Lets see if they get approved for samples!  

Found the reason for the weird voltages! 
Seems there was a slight mistake in feeback circuit designing which led to this major problem! Will post details in the weekly log! Trying to fix it in meantime for making the PCB usable.

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[GSoC Daily Log]: Work Starts!

Thursday, 29th May 2014

  • Complete Assembly of VMOD-VGA PCB. Noticed 1 more problem in PCB soldering. One signal is unconnected with the resistor network P1, Signal: Red [R7]. Criticality Level: Low
  • Next, Tried the I2C Controller from here. Quite a few modifications had to be done! Success. Successfully wrote to 2 PCF8574A devices on same bus. [ISE Project: I2C_Test.xise]
  • The I2C Controller failed to compile for Spartan3A device. Preliminary inspection revealed XST bug for Spartan3 devices. Used Mimas (Spartan 6, XC6LX9). It successfully synthesized
  • [I3C2] Second attempt with cleaned code and on Mimas, Failed Again! (argh). Getting hard to debug root cause of problem. May be bus speed or tristate logic?

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[GSoC] Official Start of coding phase

Today marks the official start of coding day of the GSoC. Unfortunately, I'm currently in midst of my End Semester exams and hence not able to relish the joy of starting work on the project. Instead, there is immense exam pressure. Sigh!

But, I'm not idle on this front either! Yesterday, I tried the I3C2 controller from This project will be using some kind of I2C core to send initialization and configuration commands to the AD9984A IC. And, the I3C2 controller looks like a good option. So, I decided to try it in my spare break time during exam studies. Bit stream is generated, I just have to upload it on Atlys and test it with PCF8574, a GPIO Expander IC, suitable for testing the I2C controller. Will keep updated in this!

See you after exams. Got to go, bye!

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[GSoC]: Trying out Atlys, Schematic creation & PCB Assembly

Not much to say this week. I've been trying out various programs on Atlys. Mostly, codes downloaded from Internet. The environment and toolchains are set up and working.
Made a schematic using Eeschema(KiCad) for the PCB. Next would be parts association and then PCB design. Almost all components are same as in previous design by Jahanzeb. One interesting thing is that, it seems that the VGA Expansion PCB designed by Jahanzeb should suffice. To that effect, I'm assembling a semi-assembled PCB, which came along with other components sent by Jahanzeb. I noticed some problems in the PCB but, overall it seems that it will work.
The project work has slowed down due to Semester Exams. But, I'll try to at-least assemble and test the PCB during any free time I take apart from studies. A working PCB would considerably reduce the efforts on the hardware side.

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[GSoC] Got a big Helping Hand!

I woke up this morning to find out that local postman had delivered a parcel to our house.  Found that it came from Jahanzeb,  the lead-developer of HDMI2USB  and contained many components which would be required for this project. My happiness knew no bounds!
Many Thanks to Jahanzeb for sending the components for this project!

Some pictures of components:


For those curious to know, I've made a Google spreadsheet of the components, and embedded it below:


Most of the passives can be directly used in the project. The AD9984A IC, VHDCI connector, VGA connector would also be used directly in the project. Same for the voltage regulators. But, ADV7604 will be used maybe in a future project due to its excellent capabilities. I can't think of the use of the USB ICs for this project. They were probably part of another project of Jahanzeb.
Overall, I've got a treasure trove of components and a greatly reduced tension of sourcing some of the components for this project! #FeelingHappy

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[GSoC] Introductory mail for the Timvideos and HDMI2USB Mailing lists

Hello TimVideos Community!

Let me take this opportunity to introduce my GSoC Project 2014 to you! The project is “VGA capture expansion board for HDMI2USB on Digilent Atlys”

Project Description:
This project will add VGA capture feature to HDMI2USB by creating a new expansion board for HDMI2USB on Digilent Atlys Hardware. To use this, one would just have to connect the expansion board to the Atlys and select the VGA input using the switches, just like selecting the video source currently.

Currently the HDMI2USB can only capture HDMI video but the VGA interface is still extremely common. Adding VGA capture will mean the HDMI2USB project has greater reach.

This project includes PCB schematic, PCB layout design, BOM along with associated HDL updates to HDMI2USB firmware. It will have only minor impact to current HDMI2USB core as it will hook into the existing components like JPEG encoder, buffers and UVC USB components.

Project Proposal:

IRC Nick: rohitksingh @ freenode

About Me:
I’m a third year Bachelor of Technology(B.Tech) student pursuing my undergrad in Electronics & Communication Engineering(ECE) from Delhi Technological University (DTU), New Delhi, India. I love electronics, hardware hacking and tinkering. And, I’m very much a DIYer guy. Some of my past projects are Autonomous Ship Navigation System, Gesture Detection using Doppler Effect, Custom repository software, Home Automation using MSP430G2553 & CC2500. The most interesting project from these was BLDC Controller and Fuzzy Logic Controller as sub-systems of Autonomous Ship Navigation System.

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[GSoC] Deciding ICs, setting up environment, KiCad and more...

So the last time I talked, I said about ordering Atlys for the project. And, the awesome news is that Atlys got delivered today itself! [Although, Digilent's distributors in India did take a long time to ship it]. I'm very excited to try it.

Brand new Atlys Box!
Atlys outside its packaging

Some, important highlights of the days spent:

Deciding ICs:

Deciding which IC to use was a very important and critical decision for the project. The Texas Instruments' TVP7002 which was initially a good option has now been made NRND (Not Recommended for New Designs) by TI. So, this was the first setback, since they don't sample NRND products and I could have got them through TI Samples program, if that wasn't the case.
There were also some other options from Analog Devices, namely,
  • AD9984A (original choice)
  • ADV7604
  • AD9985A (NRND)
The problem with AD9985A was it is older(NRND) with less sampling frequency(140 MSPS) and Bit-resolution(8-bit) and Display resolution(SXGA: 1280 × 1024 at 75 Hz)). The AD9984A seems better than AD9985A, with 170 MSPS, 10-bit and max resolution of UXGA (1600 × 1200 at 60 Hz).

The ADV7604 is another beast altogether. It has excellent capabilities, with only major problem being its cost and the BGA packaging (which is risky of project of this scale)

TVP7002 also requires unconventional, but not that it can't be done, 1.9V supply.

In the end, we decided to go with AD9984A as the preferred IC for this project and keep the TVP7002 as a backup is case of any problems.

Learning KiCad:

I started learning KiCad from scratch with the help of excellent video tutorial series by Chris Gammell. Initially, KiCad seemed very tedious to me, a long-time eagle user, but now I have definitely improved upto 80% of the capability I had on Eagle, and damn, KiCad's keyboard shortcuts are highly addictive! I love them! Never had the habit of using Keyboard shortcuts in Eagle. 
Made few schematics and PCB, same as that were used in the tutorial videos. Overall, KiCad is nice up-till now as I've started with the alpha version schematics. Rest, I'll be giving regular feedback on KiCad as the design progresses.

Setting up environment:

Ahh! This was very time consuming. I realized that my Laptop HDD's partitioning for Windows and Linux were inadequate and also very less space left for any expansion. I had Xilinx ISE on windows, but for this project I needed the latest Xilinx ISE on Ubuntu 12.04. This would take another ~15GBs. I didn't have space this much. So, the last resort was to upgrade the HDD.
Copying data as it is, even boot configuration, was a very slow and tedious job. Almost 2 days were lost in this, but data migration got completed successfully.
Next came time for installing ISE on Ubuntu. First, sourcing ISE itself is a tough task on slow net connections. But I had planned in advance and had started downloading it much earlier.
Finally, ISE part is set up properly. Since, I've now got the Atlys board, I can now set up the Cypress and Digilent toolchains.

Other Procurements:

I also ordered 6x VHDCI Connectors and 1x VMod-BB from the Digilent site directly. They got delivered in 4 days (shipping from US) as opposed to Atlys which took more than 10 days from payment to get delivered!

Exam Season!

And then, we have here in India, this time of exams, in almost all colleges. I had to spend 3 days for the practical exams, which thankfully are over now. But, its just a silence before storm!! We have got around 12 days, after which the Theory Exams will start! #BracingForTheExams

Standby by for a new post next week! with alpha design of PCB and some Atlys tests! Good Bye!

Some More pictures of Atlys! Enjoy:)


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