attiny1634 on 1.8V and 8MHz quarc

Go To Last Post
15 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

I need to use attiny1634 with 1.8V power supply and fcpu=2MHz. According to Atmel Datasheet (Atmel-8303H-AVR-ATtiny1634-Datasheet_02/2014, p.228, Fig. 24-1) this is the maximum frequency for such power supply. 
Unfortunately, there is a problem to buy 2MHz quarc oscillator in small smd case, so I would like to apply following solution:

1) to use 8MHz oscillator,
2) to start with fuse DIV8, so processor starts on 1MHz clock

3) and to reconfigure clock prescaller to /4 in order to obtain fcpu=2MHz.

Will this work properly?

I am not sure if the frequency limit from documentation does also apply for the oscillator circuit (that is before clock prescaller)?
 

Kind regards,

Piotr

 

This topic has a solution.
Last Edited: Wed. Mar 13, 2019 - 02:53 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

prom wrote:
I am not sure if the frequency limit from documentation does also apply for the oscillator circuit (that is before clock prescaller)?
8MHz internal oscillator is functional at 1.8V

(datasheet, page 230)

Table 24-2. Calibration Accuracy of Internal 8MHz Oscillator

 

"Dare to be naïve." - Buckminster Fuller

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yes, I know. The default clock configuration is internal oscillator and DIV8.
But the internal one is RC-type oscillator. 

My concern is the external one, or being more speciffic internal oscillator circuit with external quarc.

 

Regards,
Piotr

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Not answering your question, but when you state  "buy 2MHz quarc oscillator" you are meaning a quartz oscillator, not a quartz crystal? Too often users here say oscillator when they actually mean crystal.

 

2 MHz crystals are likely not available in small or smd packages as they can't be made small, while 4 MHz are available in HC49 type packages and 6 MHz and above can be in very small smd packages. Small  crystals below maybe 500 KHz are of the tuning fork type, which can be quite small.

 

If you are meaning "crystal" have you considered ceramic resonators, like:

https://www.digikey.com/products/en/crystals-oscillators-resonators/resonators/174?k=&pkeyword=&sv=0&pv2150=u2MHz&sf=0&FV=ffe000ae&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

 

There are 2 MHz oscillators available in smd packages:

https://www.digikey.com/products/en/crystals-oscillators-resonators/oscillators/172?k=&pkeyword=&sv=0&pv2150=u2MHz&sf=0&FV=ffe000ac&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

Last Edited: Tue. Mar 12, 2019 - 06:58 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

Thank you for your response.

Yes, I meant crystal. Sorry, for being unprecise.
I need crystal for accuracy reason, so I prefer quartz crystal over ceramic one.
The third option - the oscillator I eliminated due to a requirement of powering it (my application constrain).

 

Regards,
Piotr

Last Edited: Tue. Mar 12, 2019 - 07:02 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

prom wrote:
I need to use attiny1634 with 1.8V power supply and fcpu=2MHz.
A possible alternate is tiny1616, 1.8V, 5MHz with its 20MHz internal oscillator div 4 then trimmed given the 32KHz crystal oscillator.

ATTINY1616 - AVR Microcontrollers

 

"Dare to be naïve." - Buckminster Fuller

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thank you for pointing out this interesting alternative.
It looks like a chip from very new series of tinyAVR, improved by Microchip after buying Atmel.

 

I probably filtered it out before because I needed two serials, one for communication and the other for debug. After further testing I realized that I can use SPI for logging as well.

 

Regards,
Piotr

This reply has been marked as the solution. 
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

prom wrote:
this is the maximum frequency for such power supply.
That limit is for system clock speed.  The oscillator will still be stable at any in-spec voltage.  So yes, your plan to use CKDIV8 and then clock up to /4 will work.  That is in fact the recommended method (although that particular device's datasheet isn't specific about it).

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thank you for your response.

 

Regards,
Piotr

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

sbennett wrote:
... while 4 MHz are available in HC49 type packages ...
down to 1.8432MHz

Abracon - AB series - HC49/U Crystal

2MHz HC49 : https://www.mouser.com/ProductDetail/ABRACON/AB-2000MHZ-B2?qs=%2Fha2pyFadui%252BpiU6zG%2FtBV%2FJbhbfJ9H%252BSOmMr5DmOfQ%3D

 

edit: datasheet, page 4, metal jacket option (iow SMD)

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Wed. Mar 13, 2019 - 03:21 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

joeymorin wrote:
That is in fact the recommended method (although that particular device's datasheet isn't specific about it).

???

When CKDIV8 is programmed the initial value of CLKPS bits give a clock division factor of eight at start up. This is
useful when the selected clock source has a higher frequency than allowed under present operating conditions.
See “Speed” on page 229

Isn't that the same mention as in the datasheets for other applicable models?

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

theusch wrote:
Isn't that the same mention as in the datasheets for other applicable models?
I was looking for this:

Default Clock Source
The device is shipped with internal RC oscillator at 8.0MHz and with the fuse CKDIV8 programmed, resulting in
1.0MHz system clock. The startup time is set to maximum and time-out period enabled. (CKSEL = "0010", SUT =
"10", CKDIV8 = "0"). The default setting ensures that all users can make their desired clock source setting using
any available programming interface.

... which is how it's phrased in most datasheets I frequent.  The passage you quote above escaped my casual CTRL-F-ing of the t1634 datasheet.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

joeymorin wrote:
I was looking for this:

Not much different from:

 

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

joeymorin wrote:
... F-ing ... datasheet.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

theusch wrote:
Not much different from:
As I said:
joeymorin wrote:
escaped my casual CTRL-F-ing

 

theusch wrote:

joeymorin wrote:

... F-ing ... datasheet.

smiley

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]