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Absolutely, I use it with the JY-MCU connected to Serial1. Works perfect!

Beauty - I am thinking of just using a battery connected to my board directly for now, which a user would have to unplug and charge separately, but adding the option of getting one of your boards to have a simple charge system all included.

Beautiful, Thanks, I have not yet ordered the backpack, but onehorse's boards may be the answer. One followup - if I power the LC from a 3.7V battery connected to Vin and do not pug a USB in, should it startup and run correctly? I know if I want to have the USB and the batter in at the same...

Maybe this was covered, but I can not seem to find the correct information. I would like to use the Adafruit Trinket LiPo Back pack on my LC. It has a 3 connections - GND, Bat and Vin. It automatically switches from battery power to USB power when the USB on the trinket is plugged in. Would it...

Thanks! That makes good sense. Any recommendations on good dedicated analog reference ICs? matt

Just so I understand this entire discussion as it pertains to the LC, when we measure the 1.0 V internal reference (39) using the INTERNAL Analog Reference (which is Vcc), we are really measuring the the value of Vcc, since the 1.0V (39) does not change but Vcc may change. I assume that we...

I have it working! I tried the larger 10K resistor and that did not seem to change anything. I figured I would try the i2c_t3 library and after I converted my code to use that, it started working! Thanks again for all the help across the board, I do not think I would have stuck with it if it...

OK, I will try with the large resistor on SDA as you suggest, but I probably can not do it until Sunday night. Going to see my daughter get her graduate degree from Clemson on Friday! Thanks very much for all the help, I really appreciate it! Matt

Here are the picture labeled: Teensy 2.0 (Successful) Teensy LC (Unsuccessful)

When I look at picture 1 and 2, I see that in pic 1 there are 9 SCK pulses before the SDA goes high, in pic 2, there are 8 pulses before it goes high. Is there some kind of 7bit addressing thing going on that the master is not using or something? Matt

I was also able to get the Logic Analyzer working for the data coming to the Teensy 2.0. Here is a shot of that screen when receiving a packet.

OK, I have some pictures: Simple setup: Teensy 2.0 with 1.5K external pull up resistors on pin D0 and D1 with those connected to the device. Successfully reading data sent by the master: Similar setup with the external pull ups on pins 18 and 19 of the TeensyLC; Not reading data (I also tried...

I have the Diligent O'Scope and Logic Analyzer so I will fire that up and see if I can get a copy of what happens when working correctly and not so correctly. I can say that when the LC is hooked up I can see the master sending out the GC, and the LC looks like it is responding, but then nothing...

What is the best way to collect that traffic? I have a Bus Pirate, would that work? Matt

All, Is it possible that this library is not working because it does not handle "repeated starts"? I know that this is sometimes an issue. I can not seem to figure out why it is not working, and it looks like I will have to give up using the Teensy LC for this project, though it appears to be...

Well, I looked at the code and it appears that the code for the Teensy does not use the twi code and that makes sense really. But I think it will take me some time to figure out where a similar lock up is happening in the TeensyLC code, if it is happening. I will post more if I am able to...

It is the Spectra module from Hitec. It is part of the 2.4 GHz RC Airplane radio control system that they sell. It is all AVR based, and involves a module that plugs into the back of an RC Radio and a receiver that sits in the aircraft. The "Receiver" is actually a transmitter too, transmitting...

Wow, Thanks for this! After I made my post, I actually created a master that transmitted my data to the slave and I found, as you did, that setting the bit did work to receive the general call. When I connect it to the real device, however, it still does not work. I beleive the real device...

Well, I tried setting the GC bit in the register and that does not seem to work. Does anyone have the information sheet for doing IC2 on the MKL26Z64? I think that the library is just not letting the master know there is a slave on the bus interested in the data being sent. Matt

Indeed, I am trying to receive data sent out as a general call on the bus. I have looked over the code in the Wire library and the twi, and it appears that the AVR implementation will utilize an address of 0x0 as a general call. If I understand what you are saying, that not the case with the...

I loaded up the new Beta, and there is no difference. I took a snapshot of the display of the o-scope, maybe that will help? I will try to create a transmitter with the Teensy2.0 to see if I can make it repeatable for you, but that will take a day or so. Matt

I do not have the Beta, I will try it. Should I switch to the i2c_t3 library? Matt

Paul, I am using Pins 18 and 19 with external pull up resistors of 1.5k for the I2C in the same configuration I used to receive the data using the Teensy2.0 (running at 3V3). I will take a picture tonight to show. Unfortunately, I am trying to interface to a purchased device so I do not have...

So, I wired up my TeensyLC to be a slave, and I can not get it to receive any data. I have external pull ups and am using pins 18 & 19 for the I2C. Am I missing something? I have gotten this setup to work with the Teensy2.0 and the Trinket from Adafruit. I can see on my scope that the master is...

OK Guys, Last night I went ahead and hooked up my O-Scope to the I2C lines, and I found that the internal pull ups were really rounding off those wave forms. So I grabbed a couple of 1.5K resistors, turned off the internal pull ups and wired them in, and like magic, the wave forms squared off...

The device I am constructing will receive data in slave mode over I2C then send the data using serial out a bluetooth serial module continuously. It will be battery powered but only needs to be able to run for an hour or so per charge of a moderately large LiPo battery. It should be plenty of...

Very interesting information all, thanks it is a huge help. I found this posting that shows the effects of different pull ups on I2C communications, very good article. http://dsscircuits.com/articles/effects-of-varying-i2c-pull-up-resistors

Thanks, that is good information. I bet it works because I am doing I2C from one Atmel chip to another. I guess I will be prepared to wire up a couple of pull-ups since I will be going from an Atmel to the ARM Cortex-M0+. Matt

Yes, that seems reasonable. My application uses very few pins. Do you think it could be possible to connect two unused pins to each of the I2C connections needing pull up and set the pull ups on those unused pins to true? I am really trying to limit the number of components used and even getting...

In the code of the Wire library you are using, there is a comment that external pull ups must be used. Will the newer or updated library resolve that? I have a Teensy 2.0 and it works fine with the internal pull ups. I realize these are different processors. Also, there is a version of the Wire...