Go Down

Topic: Does Atmega328p Has both Full Swing Crystal & Half Swing Crystal Ossilator (Read 432 times) previous topic - next topic

yasinzaii

I was studying the crystal oscillator, while I was checking the datasheet I found that atmga328 has settings for both 
* Full Swing Crytal Oscillator 
* Half Swing Crystal Oscillator

So it means the atmega328 chip has these two building circuits that are connected to the external oscillator pins and the clock control. So, in order to use any one of these options, I will have to set the fuse bits accordingly.

I also found an article and it was mentioned that atmega328p has removed the full swing crystal oscillator circuitry? is it true.

I have Arduino pro mini and it has a ceramic oscillator but I think crystal oscillators are much preferred. Does the choice of oscillator has any impact on the weather to use a full swing oscillator or a half swing ossilator
Author of Adduino.com. Loves to talk and share about Microcontrollers.

WattsThat

It went away after a wafer process change. Another thing that went away was the 20 MHz clock capability. Pay more, get less. Thank you, Microchip.
Vacuum tube guy in a solid state world

yasinzaii

It went away after a wafer process change. Another thing that went away was the 20 MHz clock capability. Pay more, get less. Thank you, Microchip.
Well, that's bad, Why do they still have the old datasheet on their website?
Author of Adduino.com. Loves to talk and share about Microcontrollers.

WattsThat

Well, that's bad, Why do they still have the old datasheet on their website?
Microchip doesn't but there are lots of old ones floating around elsewhere on the web. Caveat emptor.

https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf
Vacuum tube guy in a solid state world

jremington

Wow! A lot has changed with the "automotive grade" line.  Other losses: the 1.8V minimum, and 100 nA power down sleep current. One to avoid, obviously.
Code: [Select]
2.7V to 5.5V for ATmega328P
Power-down mode: 1μA at 3V

The data sheet for the complete lineup is here: https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf

yasinzaii

Author of Adduino.com. Loves to talk and share about Microcontrollers.

westfw

Note that the "automotive grade" chip is theoretically a different set of chips than the non-automotive grade chips.  The "non-automotive" chips seem to still go 20MHz and have both oscillators documented.   Their datasheet is combined with other ATmegaXX8 chips:
https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf

(more likely, the automotive range are the same chips, but more thoroughly tested over a more limited range of chip specs.)

The "product change" that removed the full-swing oscillator was CANCELLED, and the "rev K" chips that would have lost the full swing oscillator never actually shipped.:
https://media.digikey.com/pdf/PCNs/Atmel/WC154601-cancel.pdf
More discussion here:  https://www.avrfreaks.net/comment/2027836#comment-2027836
(The cancellation seems not to have gotten nearly the publicity that it probably deserved, given the widespread horror at the original announcement.)


westfw

(I hadn't realized that the PCN had been canceled till I went checking to see if the change was "only" for the automotive version or not...)

Huh.  PCN in November 2015, canceled Jun 2016.  Thank you Microchip?  (acquisition finalized Jul 2016)

yasinzaii

Note that the "automotive grade" chip is theoretically a different set of chips than the non-automotive grade chips.  The "non-automotive" chips seem to still go 20MHz and have both oscillators documented.   Their datasheet is combined with other ATmegaXX8 chips:
https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf

(more likely, the automotive range are the same chips, but more thoroughly tested over a more limited range of chip specs.)

The "product change" that removed the full-swing oscillator was CANCELLED, and the "rev K" chips that would have lost the full swing oscillator never actually shipped.:
https://media.digikey.com/pdf/PCNs/Atmel/WC154601-cancel.pdf
More discussion here:  https://www.avrfreaks.net/comment/2027836#comment-2027836
(The cancellation seems not to have gotten nearly the publicity that it probably deserved, given the widespread horror at the original announcement.)

thankyou
Author of Adduino.com. Loves to talk and share about Microcontrollers.

Go Up