Mini Pro 5v 16Mhz and NewSoftSerial Fail **SOLVED**

Hi Guys,

I have a GSM chip working with an Arduino Uno using NewSoftSerial to communicate on pins 2 and 3. All perfect.

However, when I transfer the exact script and pin configuration to the Mini Pro it seems that longer character strings are not being sent to the GSM chip completely.

For instance:

This works : "AT+CGACT=1,1" This works : "AT+CNUM"

This fails : "AT+CGDCONT=1,\"IP\",\"\"" This fails : "AT+SDATACONF=1,\"TCP\",\"\",5124"

String length seems to be factor here. And, as I said, the same script works ok on an Uno.

I have done some digging around and have found various references to NewSoftSerial not working with the 3.3V 8Mhz Pro Uno. From what i can tell, it should work with the 5v variant because it runs at 16Mhz.

To completely eliminate the possibility of a faulty / mislabelled product, I have tried two different 5v Pro Mini's and tested the output voltage from the pins - both are defo 5v and i presume this means they should also both be 16Mhz (is there a way to test clock speed btw?)

Has anyone come across this before? Is there something obvious I am missing?

Many thanks in advance for any tips!


Maybe this isn't a NewSoftSerial issue.

I just tested using Tx0 and Rx1 (Serial) and didn't use NewSoftSerial.

Worked fine on the UNO but not on the Pro Mini.

lol - after everything I have been through on this project, i can't believe i'm getting stumped at the very FINAL hurdle! Agh!

I have solved the issue...

Whilst going through every possible influencing factor i reduced the input voltage from 11.5V on RAW to 10V. The script then ran flawlessly every time (following about 1,000 fails!)

The 11.5V was pretty much constant and i didn't see it spike above the documented 12v maximum. So maybe the boards regulator was interfering with the operation whist working hard :P

Anyway - documented in case anybody else hits this issue.