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106  Using Arduino / Programming Questions / Re: Checking if a device is transmitting serial data before taking an action? on: January 19, 2013, 10:43:16 am
Now see.....this is why I love this forum!  Thanks both of you for the solution to this!
107  Using Arduino / Programming Questions / Checking if a device is transmitting serial data before taking an action? on: January 19, 2013, 07:44:31 am
I have a GPS module that you can cycle between "active" and "hibernate" mode by giving a 200ms pulse on its "ON/OFF" pin.  It transmits data once per second when it is "active" and doesn't transmit any data when it is in "hibernate" mode.  The only way for me to know which state it is in is to see if it is transmitting data so for instance, when I am ready to start receiving location data i will need to toggle the "ON/OFF" pin but first I want to check and make sure that it isn't already active or else my pulse is just going to turn it off instead of on.  Likewise when I go to put it into "hibernate" mode I want to be sure that it isn't already in "hibernate" mode or else my pulse is going to inadvertently turn it on.  I wrote some code to try to check this because in my mind I need to first empty out the Serial buffer, wait a bit more than a second, and then check to see if any Serial data has come in.  I would like some guidance on the most reasonable way to do this.  My attempt at it is below.

Code:
boolean GPSisAwake()
{
  //check to see if GPS is already awake by purging serial data and then
  //checking to see if Serial data is still coming in
  while(softSerial.available()) softSerial.read();
  delay(1200);
  if(softSerial.available()) return true;
}
108  Using Arduino / General Electronics / Re: Serial.end and SoftwareSerial.end - does it clear the character buffer? on: January 19, 2013, 07:34:39 am
Code:
while(Serial.available()>0) Serial.read();

Thanks!  I have a follow up question but it is long so I will put it in its own thread under the Programming forum. 
109  Using Arduino / General Electronics / Serial.end and SoftwareSerial.end - does it clear the character buffer? on: January 18, 2013, 09:21:52 pm
I have a need to start off with an empty character buffer so that subsequent calls to Serial.read only returns new information.  If I call Serial.end and then Serial.begin(4800) again, does that give me an empty character buffer?
110  Using Arduino / Project Guidance / Re: Charging 3.7v 165mAh LiPo battery on: January 17, 2013, 10:18:46 pm
You can put together a simple circuit using something like this:

http://ww1.microchip.com/downloads/en/DeviceDoc/21984e.pdf
111  Using Arduino / Project Guidance / Re: Schematic review before sending PCB to be made on: January 17, 2013, 06:08:10 am
Quote
Basically I just need someone to take a look at the voltage regulator and LiPo charger circuits on the right hand side of the schematic and tell me if anything looks off about it.  Thanks in advance for your assistance!
I reviewed this part, compared it to data sheets and it looks OK.
Do you want to put optional pads for 2 resistors on FB & Vout (63001)

Thanks Larry for providing a second set of eyes for me!

Quote
Do you want to put optional pads for 2 resistors on FB & Vout (63001)

For this application I am just using a fixed voltage of 3.3V, however I was going to make a few extra standalone voltage regulators using the TPS63000 which is the adjustable voltage version. 
112  Using Arduino / Project Guidance / Re: Schematic review before sending PCB to be made on: January 16, 2013, 10:26:26 pm
I can't really breadboard it because the parts are tiny little SON-10 packages for the 3.3V regulator and SOT-23 package for the charger circuit.  I have designed the PCB to look as close as possible to the sample layouts in the data sheet.
113  Using Arduino / Project Guidance / Schematic review before sending PCB to be made on: January 16, 2013, 09:46:22 pm
Good evening!  A few weeks ago I asked for some help reviewing a schematic that I put together and I am hoping that I could get a quick review of some changes that I made.  Basically I just need someone to take a look at the voltage regulator and LiPo charger circuits on the right hand side of the schematic and tell me if anything looks off about it.  Thanks in advance for your assistance!


GPS_LOGGER by jg1996business, on Flickr
114  Using Arduino / Project Guidance / Re: wireless communication for standalone arduino on: January 16, 2013, 01:50:09 pm
Not hard and there are plenty of off the shelf solutions for this.  Many of the wireless modules are 3.3V so you need to do a bit of level shifting but other than that the modules are readily available.  I use these:

http://imall.iteadstudio.com/wireless/bluetooth-and-zigbe/im120723009.html

but you can buy them in shield form from this same vendor which handles all of the level shifting for you.
115  Using Arduino / Project Guidance / Re: Basic wireless switch on: January 16, 2013, 12:52:30 pm
The bluetooth shields that I linked to only require two pins, TX and RX.  You write and read to it using Serial.print and Serial.read.  Pairing and communication between bluetooth devices is handled by the shield.
116  Using Arduino / Project Guidance / Re: Basic wireless switch on: January 16, 2013, 10:30:26 am
I use one of these:

http://imall.iteadstudio.com/development-platform/arduino/shields/im120417010.html

on an arduino that is hooked up to the internet via an ethernet shield to transmit instructions received over the internet from my smart phone to another arduino with one of these:

http://imall.iteadstudio.com/development-platform/arduino/shields/im120417006.html

It allows me to control a relay board with 8 relays on it from anywhere in the world (as long as I have cell phone coverage). 
117  Using Arduino / Project Guidance / Re: Powering LEDs using transistors controlled by arduino mega on: January 14, 2013, 02:44:21 pm
The way you have drawn that, the Cathode and Anode are at the same potential so no current will flow through the LED's.
118  Using Arduino / Project Guidance / Re: Please help with switching regulator datasheet on: January 14, 2013, 10:10:38 am
Thanks!  I will use that one instead.  Probably easier to solder as well.
119  Using Arduino / Project Guidance / Re: Please help with switching regulator datasheet on: January 13, 2013, 11:17:48 pm
Yes you are.

Boo!  Oh well.  What about something like this:

http://www.mouser.com/ds/2/405/slvs520b-128772.pdf
120  Using Arduino / Project Guidance / Please help with switching regulator datasheet on: January 13, 2013, 10:49:25 pm
I was planning on using the TI TPS62237 regulator to supply 3.3V from a LiPo battery, but I just noticed on the data sheet on page 3 "Recommended Operating Conditions" that minimum supply voltage should be Vout + 1V which would mean my battery should be 4.3V which is higher than a fully charged LiPo battery.  Am I reading that correctly?  I linked to the datasheet below.

http://www.mouser.com/ds/2/405/slvs941e-197967.pdf
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