Re: PCB v3.3a

Posted by Karlis on Mar 09, 2016; 2:12am
URL: http://bluesaab-forum.90.s1.nabble.com/PCB-v3-3a-tp222p259.html

Viggen wrote

Ok two more n00b questions, is there a reason for/against running at 9600 baud? Have there been issues at 115200, or is it just preventative maintenance? I jumped the two pads but wasn't really sure if I needed to do so

By default, RN52 bluetooth chip uses 115200bps, that's the reason we chose to go with this baud rate. However, during some extensive tests performed recently, I noticed that when we communicate with RN52 via ATMEGA328, the signal becomes more "bell-shaped" => very bad. :) I stepped down the code to use 9600bps and now the signal is nice and square. As it should be. So long story short - 9600bps is the way to go. I've implemented the changes in the code already and have uploaded them to Github.

Viggen wrote

And then I've been itching to see if I've assembled this properly, if I'm reading your earlier post correctly I can jumper the PWREN and 3V3 pads so the RN52 is powered up. Can I then run the old software on this PCB or is it a no go without the new software (in which case I won't bothering jumping them)?

Yes. By shorting PWREN with 3V3 pins you'll get the RN52 in "constantly on" state. Which is also the case for all hardware revisions prior 3.3A. We had some issues with enabling the power "on demand" using previous bluetooth chips, that's why we opted to go with "constantly on" option. Now with 3.3A hardware revision we'll be able to put RN52 to sleep and wake it up when needed.