Nano 328p vs 328PB

Other Hardware General Electronics
1

Hello

I have a number of NANO boards which, as it turns out, have the 328PB soldered on them.
The -PB versions have extra functionality over the standard -P version.
2 functions come through the procesor pins 3 and 6: SDA1 and SCL1, for an extra I2C bus.
In the -P version these pins were: 3=GND and 6=VCC
I noticed that on the boards with the -PB processor these pins are
still connected to the power lines GND and VCC
Apart from the fact that these processor pins are not externally
connected to 2 additional pins and therefore useless, they might even get damaged. I think...

Can somebody confirm this ?

Regards,
Rob

3

You are right. The PB is NOT a drop in replacement for thr the P.
If you should declare those pins as outputs you could indeed damage the part

4

But if you don't, it should be OK. The pins are on PORTE, which doesn't exist on the normal P version, so you'd have to go to some effort to make them outputs.

5

Yes the pins default to inputs so it should be OK.
It is a bad hardware design.

6

What is the marking on the PB chip exactly?

7

The exact marking on the chip is:

Atmel
MEGA328PB
-U
1743D TW
A4BUJD

8

Do you have a good reason to believe that the chip is genuine?

9

Likely it is not a 'design' at all, but a (cheaper, more available) ATmega328PB chip dropped onto a PCB that was created for an ATmega328P.)

10

I have no reason to believe that the chip is genuine or not.
Years ago I bought a few nano's for some experiments
Some boards had the 328P and some boards had the 328PB on it.
So I think that what westfw writes could be true: cheaper and more available.

11

Looks like you aren't the first.

https://forum.arduino.cc/t/warning-nano-clones-with-mega328pb-u-chips/520381

I can't find anything that suggests 328PB-U is an Atmel marking. I think their's would be 328PB-AU.

12

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