328PB mcu question - Page 1
Forum section: electronics / beginners

author: trilerian
author_rank: Regular Contributor
timestamp: November 17, 2023, 05:32:39 pm
content: I have a couple of designs using the 328p in the tqfp package. I bought some 328PB by mistake. After trying to burn the bootloader to them I realized what I did, and edited the config file to be able to burn them as 328P. I tried burning the bootloader as a 328PB, but never could get it to work. So the other day I actually pulled up the data sheet on the 328PB and did notice a few pin changes from the 328P. Aside from a couple of extra timers, which will be useful, we lose a vcc and a ground pin. However, my current pcb designs have decoupling capacitors on those pins that are no longer vcc and ground. What will be ramifications of this? Basically I am pulling one pin low to ground with no resistor and one pin high with no resistor. But the pins are not being used? I can just not use the capacitors and peel up the traces to vcc pin, but for some reason cutting a new pcb doesn't sit well with me. I don't think pulling an unused pin to ground will hurt anything.Does burning the bootloader as a 328P make any difference to those pins? My assumption is to be able to use the extra pins in a future design, I need to burn the bootloader as 328PB. Realistically speaking, the 328PB is cheaper, so I would prefer to go that direction. Any future designs I make will take that into account.

author: wraper
author_rank: Unknown
timestamp: November 17, 2023, 05:47:01 pm
content: QuoteNo.QuoteAs long as you don't configure them as outputs, should be fine. Enabled pull-ups on the port will increase current consumption a little bit through former GND pin.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 17, 2023, 06:30:48 pm
content: in my case : you had / have to find in arduino the 328pb librairies ... i have some of theses and it did not worked well ...even avrdude avrdudess had some problems ...had to switch to the P variant ...

author: Faranight
author_rank: Unknown
timestamp: November 17, 2023, 07:13:46 pm
content: I too was initially using ATmega328P, but later switched to using the ATmega328PB variant in my projects. While not pin-compatible, I very much liked the two extra 16-bit timers. Now I've switched to AVR32DB32.

author: trilerian
author_rank: Regular Contributor
timestamp: November 17, 2023, 07:14:11 pm
content: Quote from: wraper on November 17, 2023, 05:47:01 pmGreat!Quote from: coromonadalix on November 17, 2023, 06:30:48 pmYeah, I downloaded the support for the 328PB, and there is a config file for it in the bootloader, but it still doesn't work. But, I was also applying 5v to one of the pins that is no longer VCC while trying to burn the bootloader.

author: trilerian
author_rank: Regular Contributor
timestamp: November 17, 2023, 07:28:13 pm
content: Quote from: Faranight on November 17, 2023, 07:13:46 pmOne day I'll get away from the 328P!How is the internal vref on the AVR32?Looks like with a 12 bit ADC and an internal vref of 4.096 I could save quite a bit of money moving to that design over using a precession voltage reference and an external adc for my 328P.I was going to try to port some stuff to the ESP32, but then found out how awful the ADC is.

author: Faranight
author_rank: Unknown
timestamp: November 17, 2023, 07:45:58 pm
content: Quote from: trilerian on November 17, 2023, 07:28:13 pmYou have actually three separately configurable Vref's - one for ADC, one for DAC and one for AC's.I think some analog peripherals should even have an additional 8-bit resistor ladder that lets you divide the selected reference voltage even further.EDIT: There are also up to three (depending on model) signal-conditioning opamps inside the MCU.