Brad Fernandez Build Log


Hello Everyone!

My name is Brad Fernandez. I am from Tampa Fl. and I have been heavily involved in electronics for about three years. I have had good success with programming developer boards and now I want to move forward to designing and buidling my own.

I have already completed getting to blinky and I am currently looking at the CE Header course.


Welcome Brad.I look forward to hearing more of your progress,


Well I finished the layout portion of the CE Header. I Have ordered my boards from Osh Park. Now on to the Sensor board.


Ok here is a little progress I made. I adapted the CE Header lesson and here is the schematic for a photon header adapter. Working on the footprints next.


CE Header to Photon adapter. Well that was fun. Here is the final footprint I will be sending off to Osh Park.


Looks great! Keep it up!


OK Another night of work down. I got my AD2 today so I played around with that for a little while. It is a neat and surprising powerful tool. Then finished my Sensor board schematic and got all the foot prints chosen.


It looks like it is coming together. One thing to watch though, on the DS7505, the data sheet makes the comment

Bus Idle or Not Busy: Both SDA and SCL remain high.
SDA is held high by a pullup resistor when the bus is idle,
and SCL must either be forced high by the master (if the
SCL output is push-pull) or pulled high by a pullup resistor
(if the SCL output is open drain).

In my case, I used a Teensy and this was a trap I fell into. I had to add 4k7Ω pull up resistor to each of the SDA and SCL lines before I could talk to the DS7505.


The SCL and SDA lines of the I2C bus always require pull-up resistors as it uses open-drain/open-collector line drivers. Depending on the length of the bus, the bus voltage and the max speed of the bus you might want to use stronger pull-ups, such as 1K for 3V3 or 1K5 for 5V. The pull-up resistors have to overcome the parasitic capacitance of the line at the max frequency.


Good catch. Thanks guys. I added the pull-up resistors to my sensor board last night. I’ll post pictures of my layout and schematic later tonight. I was tired last night and forgot to post my updates.


Alright I finished up my layout and ordered the sensor board from osh park. I also ordered some headers and a resistor/capacitor book. Now I wait! Here are pics of my final schematic and layout. I’m going to move on to simulation while I wait for parts.



Just a little up date I have been working through the Current Sink Or Swim videos while I was waiting for my parts from Osh Park. Well I got my parts today and started assembling. worked through all my resistor and capacitor values. Then Got to the 595 and 74hc595 and realized I had purchased the wrong packages I got tssop packages and needed soic. Doh! Oh well ordered the correct ones now back to CSOS till they arrive. Also still waiting for the Photon CE Header board as well. Here is a photo of the mistake as well as my Getting to Blinky and CE Header Board.


Treat this as an opportunity to practice your bodging skills :slight_smile:


“Bodging” implies doing something poorly or badly, I prefer to think of it as improvising. :wink:


And how would you suggest I bodge this? Not sure how I would go about that.


One thing is certain, It would take a quite a bit of patience.
Some inspiration…


So, update time. I have completed the CE Header Course. I had a little trouble with my desktop so I had a little trouble diagnosing why my shift register lights would only light up one way regardless of what I typed in to the serial monitor. Got my self a New Evo 970 got my desktop back up. Much better performance then the old 55 gig sata drive. Woot! Hooked everything back up and figured out the Arduino sketch had a static value that it was passing to the teensy. Changed that to accept key strokes insteadn and boom we’re back in business. Here are some pics of the completed board and the AD2 scope.


I have also been making prgress on the Current Sink and Swim course. I have completed my layout and everything has been ordered as of today. I will post pictures below of my layout so you guys can see what I did to try and make the board a little smaller then it was in the course. It ended up being 1.25"x1.45". I may fail completely with that idea but that’s part of the fun right. Let me know what you uys think.



Looks good! I give my first attempt at sizing based on what Chris tries but usually I end up going bigger just to help with soldering. I think some of the people on the course are using reflow ovens and solder masks so that takes the small piece soldering issue out.


Those two boards came out great!