Atmel chip changes

Interesting notice from Digikey today:

Atmel ATmega Revision Change Notification:
This email is to notify you of a recent Atmel revision change. Our records show you have purchased at least one affected part and this change may affect the application when receiving future orders of ATmega parts.

One important change is the removal of the Full Swing Crystal as a clock source option. If your application is currently using this, it will need to be converted to one of the other supported clock sources listed on page 28 of the datasheet.
Changes
New die revision changes:
• Full swing crystal oscillator not supported
• Power Save mode current consumption increased
(ATmega48P, ATmega88P, ATmega168P)
• Parallel programming timing modified
• Write Wait Delay for NVM is increased
• Device ID

Please see the attached [Atmel PCN WC154601](http://img.digikey.com/Retractions/WC154601 - PCN-12-23-2015.pdf) for the complete list of changes and affected parts.

For additional service or technical support regarding this notification, please contact Digi-Key Customer Service at 800-858-3616 or customer.service@digikey.com.
Sincerely,
Digi-Key Customer Service

WC154601 - PCN-12-23-2015 Atmel changes.pdf (385 KB)

I don’t see Atmega328P-PU listed there anywhere …

Thanks. Good to know. I think I have a full swing in one of my projects.
The remove of full-swing is only for specific chips. I think the others will keep it (for now).
The Device ID changes for debugWIRE, but the signature stays the same. For the Arduino everything is the same.

I'm glad to see that the ongoing improvements to semiconductor manufacturing allow for distinct product enhancements... oh, wait...

(ATmega8 BETTER keep the full swing oscillator. I have some standard-ish resonators that don't work with the low-power oscillator (although the ATmega8 also documents that.))

I'd be worried about the ATmega1284P, though. Is it next? It seems to have some weird problems for which using the full-swing oscillator is a workaround. (maybe they'd go away with the change of process/fab as well?)

Updated 328P & siblings datasheet:

40.8 Errata ATmega328P
The revision letter in this section refers to the revision of the ATmega328P device.

40.8.1 Rev K
• Full swing crystal oscillator not supported
• Parallel programming timing modified
• Write wait delay for NVM is increased
• Changed device ID
• Analog MUX can be turned off when setting ACME bit
• TWI Data setup time can be too short

http://www.atmel.com/devices/ATMEGA328P.aspx datasheet updated 11/2015

The 1284P has not been changed in this fashion so far.

What is the reason to end support of full swing crystal oscillator?

@westfw

It seems to have some weird problems...

Can you be more specific? I've tested 1284P with low power crystal oscillator some time ago (concerning to my Arduino 1284P variant) and as I remember, it won't start. I had to use full swing but I didn't examine it more deeply. I'm using full swing with slow rising power in flat-rate.

Can you be more specific?

It seems serial RX to the 1284 can interfere with the controller clock as it is physically close to the XTAL1&2 pins.
Setting to full swing alleviates the sensitivity.

2016-01-14_0-54-54.png

.

Hmm, I have no such experience.

It seems serial RX to the 1284 can interfere with the controller clock as it is physically close to the XTAL1&2 pins.

The symptom was that bootloader-based uploads would fail in particularly mysterious ways.

Can someone please explain the physical difference between FULL SWING and LOW POWER crystal oscillators
Bob

Here’s what the datasheet for the '328 currently shows:

"9.3 Low Power Crystal Oscillator
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be configured for

use as an On-chip Oscillator, as shown in Figure 9-2 on page 29. Either a quartz crystal or a ceramic resonator

may be used.

This Crystal Oscillator is a low power oscillator, with reduced voltage swing on the XTAL2 output. It gives the

lowest power consumption, but is not capable of driving other clock inputs, and may be more susceptible to

noise in noisy environments. In these cases, refer to the ”Full Swing Crystal Oscillator” on page 30."

"9.4 Full Swing Crystal Oscillator

Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be configured for

use as an On-chip Oscillator, as shown in Figure 9-2 on page 29. Either a quartz crystal or a ceramic resonator

may be used.

This Crystal Oscillator is a full swing oscillator, with rail-to-rail swing on the XTAL2 output. This is useful for
driving other clock inputs and in noisy environments. The current consumption is higher than the ”Low Power

Crystal Oscillator” on page 29. Note that the Full Swing Crystal Oscillator will only operate for VCC = 2.7 - 5.5

volts.

We have several products (sold in hundreds) that use 168's at 20MHz (but most at 16MHz), they have standard HC-49S crystals and low value caps, do we need to seriously consider this change, or am I missing something ? Ta

Well, do you use full swing fuse settings for that product? If you do, then this change may make you re-evaluate that setting.

ATMega168A-MU : fuse settings are 0xDA3F, which implies “Ext.Crystal Osc 8.0-… blah blah” using 20MHz crystal

Even after the explaination, I am still non-the wiser as to what the difference is between full swing and low power, sorry for my ignorance

Low power - the oscillator circuit outputs a less than 5V signal (assuming VCC = 5V) on the XTAL2 pin. Smaller voltage swing, less current drive capability → do not connect it to other circuits.
Full swing - the the oscillator circuit outputs a 5V signal (assuming VCC = 5V) on the XTAL2 pin. Large voltage swing, more current drive capability → can be connected to other circuits.

If the XTAL2 pin is not connected to other devices and the crystal circuit is properly guarded, see page 14- 15 of the attached, you may be okay. I would try the settting change with your current design, and either fix it if there are issues, or stock up on existing parts.

atmel-AVR042-avr-hardware-design-considerations_application-note 7-2013.pdf (758 KB)

From the quote from Atmel from HERE

As a commercial company we have to change designs, production facility and so on to stay competitive. Clearly any change to an existing device is inconvenient for the users - no discussion about that. When we send out a PCN it is to inform our customers so that they can act on the change to minimize the impact. In this case we knew that the removal of the full-swing oscillator could be a problem for some customers and for that reason the old revision of the device can be ordered using a special order code. If you need the full-swing oscillator or need to run at more than 16MHz please contact you local sales office (Atmel of distributor): They know the special order codes.

“If you need the full-swing oscillator or need to run at more than 16MHz please contact you local sales office”

Well we appear to come under the OR part :frowning:

Thanks for your reply Bob, we dont need to output 5v on any XTAL2 pin

I had missed the part about the special order code. Wonder what the min quantity will be on that? Or if places like Digikey, Mouser will stock both?

mcnobby:
ATMega168A-MU : fuse settings are 0xDA3F, which implies "Ext.Crystal Osc 8.0-.. blah blah" using 20MHz crystal

Even after the explaination, I am still non-the wiser as to what the difference is between full swing and low power, sorry for my ignorance

Ok, so your fuse settings indicate you are not using full swing anyway. Looking at a fuse calculator like this:

When you put your fuse settings in the calculator it does not show in the low fuse presets a "Ext. Full-swing Crystal" setting, just just shows the "Ext.Crystal Osc.; Frequency 8.0-" like you mentioned, so that is a low-power crystal setting. The full swing just sends more voltage through the crystal, making it more resistant to noise and making it use more power.

It appears to me that even with the old version of the chip, you are supposed to use a top frequency crystal of 16MHz when you are using the low-power setting. I don't think the data sheet makes it crystal clear :wink:

I take it you are already over-clocking if you have a 20MHz crystal and not using full swing. You are probably minimally impacted, unless you want to stop over-clocking.

Do any of you more experienced guys have corrections to make on what I've said? I'm still a newbie compared to a lot of you.

Thank you for your assistance dmjlambert :slight_smile:
That has made things a lot more clear for me

We may have to tread very carefully here as nearly all of our product (with Atmel >16MHz or not) is made in the far east, and it is unknown exactly what sources they use, we should make them aware of this change too

Regards