Arduino Nano V3 Clock Out 16 Mhz

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1

Hi folks,
setting Clock Out on Arduno Nano V3 is driving me crazy.
Target is : Enable CKOUT in order to use this clock as source for other devices.
Reading documentations, fuse and avrdude are both needed.
About the fuse, documentations is talking about to set the 6th bit (counting from 0) on low_byte fuse to zero.
Well, I got default values in boards.txt where this value is set to 0xFF (11111111)
In order to enable clock out i thought to switch only bit 6 to 0, obtaining 10111111 = 0xBF
According to Atmega328P docs this bit should enable pin14 - PB0 to produce clock signal out.
This pin corresponds on D8 on Arduino Nano.

So I've modifed the value to
nano.menu.cpu.atmega328.bootloader.low_fuses=0xBF

compiled the sketch, connected the oscilloscope on D8,but... nothing happens
I've tried also to force avrdude with the options -U lfuse:w:0xbf:m but nothing changes

Do anyone have an idea on producing correctly a clock signal out possibly to 16Mhz ?

Thanks in advance !!!

2

The fuses are only set when you do a Tools > Burn Bootloader, for which you need to connect an ISP programmer to your Nano. The fuses are not set when you do a regular upload to your Nano.

3

First of all, thank you for replying me.
About your valuable considerations I've done the following step :

  1. Get an Arduino Uno connecting SPI wires to target device
  2. Loaded the example Arduino ISP
  3. Compiled and load this sketch on Uno
  4. Selected Tools->Arduino Programmers as ISP
  5. Modified the values in 0xBF in boards.txt
  6. tools->bun bootloader

Leds was blinking...
This is a succesfull procedures I've used in the past to load boot loader, but nothing.. I still obtain no clockout.
Any further idea ?

4

AndreaOrazi:
5) Modified the values in 0xBF in boards.txt

After modifying boards.txt you need to exit all Arduino IDE windows and then restart the Arduino IDE before your changes take effect.

AndreaOrazi:
Leds was blinking...

Did the Arduino IDE show the message "Done burning bootloader"?

5

After following your istrunctions no :
here the "debug":

C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avrdude -CC:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf -v -patmega328p -cstk500v1 -PCOM8 -b19200 -e -Ulock:w:0x3F:m -Uefuse:w:0xFD:m -Uhfuse:w:0xDE:m -Ulfuse:w:0xBF:m

avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is "C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf"

Using Port : COM8
Using Programmer : stk500v1
Overriding Baud Rate : 19200
AVR Part : ATmega328P
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PC2
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :

Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack

eeprom 65 20 4 0 no 1024 4 0 3600 3600 0xff 0xff
flash 65 6 128 0 yes 32768 128 256 4500 4500 0xff 0xff
lfuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
efuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
lock 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00

Programmer Type : STK500
Description : Atmel STK500 Version 1.x firmware
Hardware Version: 2
Firmware Version: 1.18
Topcard : Unknown
Vtarget : 0.0 V
Varef : 0.0 V
Oscillator : Off
SCK period : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000 (retrying)

Errore durante la scrittura del bootloader
Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
this check.

avrdude done. Thank you.

6

ISP programmer is not connected correctly. Recheck all wiring.

7

ok.
Fixed : was not a wire problem.
The only thing I've made is to insert a 0.22uF capacitor between pin 1 (reset) and GND.
After that situation is (quite) stable.
Thanks anyway for helping me. :wink:

8

Clock out is only available when using an external oscillator. So if you try this in a wilt an XTAL connected to XTAL1 and XTAL2, the cristal oscillator wont work, and you must use an external oscillator, or the internal oscillator. This may cause problems with serial coms, because it cal deviate +/- 3% !!!

So when using this, remove the Xtal (AFTER PROGRAMMING THE FUSES TO USE THE INTERNAL OSCILLATOR), and only when you are using in external oscillator set the fuses after connecting the external oscillator. To use the SPI programming mode, you must use a working oscillator, so if you remove the Xtal first, you 'll have no working oscillator, and you can't program anything

If you need an oscillator, the FT323RL used on the original NANO can be programmed to produce an 12 MHZ clock signal on one of the pins, however this will only work when the USB line is connected, not in standby mode. This is slower than the standard 16 MHZ clock, but will also work with the Nano on 3.3 Volt. You will have to adjust the baudrate of the bootloader accordingly, or recompile the bootloader for 12 MHz.

Also you must add a Arduino Nano @ 12MHZ as a new device, or the compiler will generate incorrect timing intervals, serial speeds and all other timing sensitive items, so this is not advised to be used, but mey be usefull as external clock for programming using the SPI interface

9

MiniCore has a 12 MHz ATmega328P hardware definition and bootloader: