ATtiny85 @ 16mhz with internal High Frequency PLL Clock

Development Libraries
1

Hi guys, experimenting we found the possibility to use an ATtiny85 or Pico85 SMD @ 16mhz with the internal High Frequency PLL Clock.
To do this you have to regulate fuses removing divider, a easier technique is to modify boards.txt with the new clock and then program the MCU.
Here a video with software servo working well:

2

could you explain what you've done? How have you set the fuses?

3

This entry seems to work well...

###########################################################################

attiny85at16p.name=ATtiny85 @ 16 MHz  (internal PLL; 4.3 V BOD)

# The following do NOT work...
# attiny85at16p.upload.using=avrispv2
# attiny85at16p.upload.using=Pololu USB AVR Programmer

# The following DO work (pick one)...
attiny85at16p.upload.using=arduino:arduinoisp
# attiny85at16p.upload.protocol=avrispv2
# attiny85at16p.upload.using=pololu

attiny85at16p.upload.maximum_size=8192

# PLL Clock; Start-up time PWRDWN/RESET: 1K CK/14 CK + 4 ms; [CKSEL=0001 SUT=00]
# Brown-out detection level at VCC=4.3 V; [BODLEVEL=100]
# Preserve EEPROM memory through the Chip Erase cycle; [EESAVE=0]
# Serial program downloading (SPI) enabled; [SPIEN=0]

attiny85at16p.bootloader.low_fuses=0xC1
attiny85at16p.bootloader.high_fuses=0xD4
attiny85at16p.bootloader.extended_fuses=0xFF
attiny85at16p.bootloader.path=empty
attiny85at16p.bootloader.file=empty85at16.hex

attiny85at16p.build.mcu=attiny85
attiny85at16p.build.f_cpu=16000000L
attiny85at16p.build.core=tiny
 
###########################################################################
4

Using ATtiny85 @ 16Mhz internal clock is the input voltage range 2.7V - 5.5V?

5

From Figure 21-2. Maximum Frequency vs. VCC in the datasheet it looks like the voltage range at 16 MHz is about 3.3V to 5.5V.

6

Will this work with the Attiny45?

7

Yes. Maybe...

27.2 Errata ATtiny45
27.2.3 Rev B and C

  1. PLL not locking
    When at frequencies below 6.0 MHz, the PLL will not lock
    Problem fix / Workaround
    When using the PLL, run at 6.0 MHz or higher.

27.2.4 Rev A
3. PLL not locking
When at frequencies below 6.0 MHz, the PLL will not lock
Problem fix / Workaround
When using the PLL, run at 6.0 MHz or higher.

Running an ATtiny45 at 16 MHz using the PLL should work just fine.

8

This has not been posted on in a while, but I just want to add to this forum:

The SoftwareServo library works well ONLY if your lfuse is c1. I tried df and that did not work; it only worked at 8MHz for me

So, c1 works the best

Thanks

9

Hello.

I try this, but it dont work.
Then i try to remove some lines and edit some :

attiny85at16p.name=ATtiny85 @ 16 MHz  (internal PLL 4.3 V BOD)

# The following DO work (pick one)...
###attiny85at16p.upload.using=arduino:arduinoisp               <- !!!
# attiny85at16p.upload.protocol=avrispv2
# attiny85at16p.upload.using=pololu

attiny85at16p.upload.maximum_size=8192

# PLL Clock; Start-up time PWRDWN/RESET: 1K CK/14 CK + 4 ms; [CKSEL=0001 SUT=00]
# Brown-out detection level at VCC=4.3 V; [BODLEVEL=100]
# Preserve EEPROM memory through the Chip Erase cycle; [EESAVE=0]
# Serial program downloading (SPI) enabled; [SPIEN=0]

attiny85at16p.bootloader.low_fuses=0xC1
attiny85at16p.bootloader.high_fuses=0xD4
attiny85at16p.bootloader.extended_fuses=0xFF
#attiny85at16p.bootloader.path=empty                            <- !!!
#attiny85at16p.bootloader.file=empty85at16.hex          <- !!!

attiny85at16p.build.mcu=attiny85
attiny85at16p.build.f_cpu=16000000L
#attiny85at16p.build.core=tiny
attiny85at16p.build.variant=tiny8                             <- !!!
attiny85at16p.build.core=arduino:arduino                <- !!!

Then i can use my Arduino Uno as ISP.

But i have some problems with the servo moving. I made a short testing sketch :

void loop() {
  
  for (int i=20; i<160; i++){
    servo1.write(i);
    delay(10);
    SoftwareServo::refresh();
    
  }
  
  delay(1000);
  
  for (int i=160; i>20; i--){
    servo1.write(i);
    delay(10);
    SoftwareServo::refresh();
    
  }
  delay(1000);
}

The servo will move slowly, the fast many times in a short way, the again slow....not good !
I have also try without servolib.

 void servoAngle(int angle, int Speed){
  digitalWrite(servoPin, HIGH);
  angle = map(angle,0,180,400,2200); // 500 , 2500 Winkel in Zeit umrechnen, siehe Bemerkung!
  delayMicroseconds(angle);
  digitalWrite(servoPin, LOW);
  delayMicroseconds(Speed);
  
}

void loop() {

   for (int i=180; i>=50; i--){
    servoAngle(i,15000);
  }
  
  delay(2000);
  
  for (int i=50; i<=180; i++){
    servoAngle(i,15000);
  }
   
  delay(2000);
}

But here i am testing about the values in the map funktion.
With 8Mhz this will be

angle = map(angle,0,180,500,2500);

But her also the movement ist not so good as with my Arduino Uno.
Short ways are sometimes to fast, or dont be moved.

Then i see this with 16Mhz and i hoped it will be better, but its not.
Dont understand why the servo is moves so good in this video :frowning:

EDIT:
I think i have a power problem. First test was with my arduino as power supply.
The led are flickering a little.
Then i try with an external batterie pack for the servo and now it moves smooth.
I will try to install an big capacitor in the power line for the servo