TinySA Team,

Today, I took a programmed Arduino Nano (with TinySA for the Nano) and performed the 'surgery' to the schematic to make the Nano a 3.3VDC compliant device by replacing the regulator to a 3.3V type (from 5V) and a few cuts and jumps (I improvised on the cuts and took out a diode where it was clearly not being used). I am here to tell you that while all that is possible and all the measurements I took and the checkout of the I/Os looked good...It WON'T communicate to Erik's TinySA Windows PC program. The PC 'sees' the modified board as a 'COM4' device (sometimes this can also be a 'COM11' device) but no matter what, the TinySA PC program DOES NOT see the 'COM4' device when powered and running and it cannot even start it because it never makes the list - - the list just shows 'Mockup. It may work for other applications, but not for TinySA, and it also becomes more problematic to upload a sketch to the device even when powered in-situ in the setup, too - multiple bad read and write errors.

In closing, I would NOT advise doing this for the Arduino Nano for the TinySA application. I have become a believer that Level Shifting is necessary to make this work for the TinySA and a standard 5V programmed Arduino Nano - that's how I'm going to try mine next.

73 de Marty, KN0CK

On Feb 16, 2020, at 8:27 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

?Could you reliably download to the Nano before you did the surgery?
Have you tied the old 3.3v and old 5.0v (now 3.3v) rails together?
Have you measured the output of the 3.3v regulator, verified it is a solid 3.3v even when downloading?

I haven't tried it with a tinySA yet, but I do have a Nano hacked to 3.3v
that reliably downloads firmware?from a USB host.

Jerry, KE7ER

On Sun, Feb 16, 2020 at 08:08 PM, Marty Wittrock wrote:

TinySA Team,

Today, I took a programmed Arduino Nano (with TinySA for the Nano) and performed the 'surgery' to the schematic to make the Nano a 3.3VDC compliant device by replacing the regulator to a 3.3V type (from 5V) and a few cuts and jumps (I improvised on the cuts and took out a diode where it was clearly not being used). I am here to tell you that while all that is possible and all the measurements I took and the checkout of the I/Os looked good...It WON'T communicate to Erik's TinySA Windows PC program. The PC 'sees' the modified board as a 'COM4' device (sometimes this can also be a 'COM11' device) but no matter what, the TinySA PC program DOES NOT see the 'COM4' device when powered and running and it cannot even start it because it never makes the list - - the list just shows 'Mockup. It may work for other applications, but not for TinySA, and it also becomes more problematic to upload a sketch to the device even when powered in-situ in the setup, too - multiple bad read and write errors.

In closing, I would NOT advise doing this for the Arduino Nano for the TinySA application. I have become a believer that Level Shifting is necessary to make this work for the TinySA and a standard 5V programmed Arduino Nano - that's how I'm going to try mine next.

73 de Marty, KN0CK

Hi

Please be aware that the Atmega328 is operated beyond specifications, 8161D–AVR–10/09 section 28.3 Speed Grades, when subject to 3,3 V and a 16 MHz clock. Between 2,7 V and 4,5 V the slope is about 5,6 MHz/V resulting in a safe operating clock of 13,3 MHz. So timing could be affected. There are Arduinos with an Atmega328 running at 3,3 V available but they run at 8 MHz:



In this day and age many devices run at 3,3 V so I would strongly recommend using an Arduino Zero, i.e. ARM M0+ SAMD21 type. It may be a little bit more expensive but you get SO much more computing power and built in USB:



Bo
www.rudius.net/oz2m :: www.rfzero.net