Messages

1

General Discussion / Tiny Proto Shields

« on: April 07, 2015, 06:56:43 PM »

I am putting together a small project that needs to have a few connections from the Tiny Arduino board to the outside world so I guess it would be appropriate to use either the Tiny Proto Shield 1, the Tiny Proto Shield 2, or Tiny Proto Shield 3.  Since I only need to provide Vcc, ground, two digital input/outputs and one analog input, I decided on using Proto Shield 3.  This will leave the shields with more inputs/outputs for a future project or two.  My problem:  Even with a magnifying class, I cannot read the silk screen annotation on the board next two three of the pins.  When I go to the tiny-circuits web page, the same pins are a little out of focus.  Can anyone help me with the identification of the two middle pins on the second row (from the bottom) and the pin on the bottom row which is all the way to the right?  I'm guessing the two in the middle of the second row are IO 8 and IO 9.  The one on the bottom right could be IO 0 but I'd prefer not to have to guess.  I guess this is the price we have to pay to have such a tiny platform to work on!
Thanks in advance for anyone who can help with this.

2

General Discussion / Powering the TD with automotive 12V

« on: March 28, 2015, 04:50:46 PM »

I have ordered the starter kit and plan to build an ammeter that measures 0-650A (it's an EV!).  What it's actually measuring is a small voltage (750 mV = 500 Amps) across a shunt resistor at the negative end of the high voltage loop of the car.  I will use a DC:DC converter/isolator to eliminate ground problems (12V system is grounded to the chassis but the 120VDC system is not, it is floating).  First stage of my ammeter will be an op amp diff amp (high impedance) that simply measures the difference between voltages of the two terminals of the shunt resistor.  That will be followed by a precision absolute value (full wave rectifier) op amp circuit that will allow me to measure propulsion current as well as regenerative braking current (flows in opposite direction to charge batteries while braking).  My question:  to power the Arduino board and its shields, do I need to provide 3.3V or 5 V, and how well regulated does Vcc have to be?  I'm sure my newness to this shows in the ignorance of my question, but I'd really appreciate some help from some of the more experienced members.

I got no responses to this in about 10 days, so I thought I'd share what I found out separately.  The Tiny Duino has no voltage regulator on board so I will have to provide one externally.  It needs Vcc voltage between about 3.0 to 5.5 V DC.