Dutchtronic Oscilloscope Clock - How do i change the refresh rate? - Page 1
Forum section: electronics / projects

author: MostlyHarmless
author_rank: Newbie
timestamp: October 26, 2024, 04:14:35 pm
content: Hey everyone,i have just finished my build of aDutchtronix Oscilloscope Clockboard, i flashed the Atmel AVR328U today with the source code(in hex format, so i cannot read it or edit it) and it works with a proper display on a HAMEG 203-6 20Mhz scope, but for some reason the refresh rate is only 10 Hz so it flickers really badly - its such a shame because it was not cheap to build and if only the refresh rate were higher it would be perfect.Does anyone out there know how to change the refresh rate or even perhaps know how to contact the original designer, I've emailed the address on the Dutchtronix website but i am not sure whether anyone maintains it anymoreheres hoping its not as obscure as i think it might be to build one these days

author: TurboTom
author_rank: Super Contributor
timestamp: October 27, 2024, 02:53:10 pm
content: Did you verify the MCU oscillator is running at 20MHz? Maybe the clock configuration of the is MCU set wrong and it's running off its internal RC oscillator ("standard" configuration)? I don't see another possible cause for your observation than the wrong MCU clock frequency since otherwise, your board appears to be working normally.Attachment: My "slightly" modified Dutchtronics scope clockP.S.: I found my original Dutchtronix board and added a scope screenshot that shows a repetition rate round about 225Hz. Considering that an "unconfigured" ATMEGA will run on its internal 4MHz RC oscillator with a 1/4 prescaler for the processor clock (1MHz Fclk), the "10ish" Hz repetition frequency appears plausible.Edit: Information added

author: 6CW4
author_rank: Newbie
timestamp: December 11, 2024, 10:55:49 pm
content: Hello - I have the exact same flicker issue with my clock....Can you please share what you did to resolve the issue.I suspect the fuse settings are not correct on the 828P Chip I programmed.Thank you,Paul K.

author: TurboTom
author_rank: Super Contributor
timestamp: December 15, 2024, 11:47:15 am
content: Since my occupation with this project was several years past, I don't remember all the details. But in the project directory, I found some useful remarks:Text file "AVR-Fuses":Code:Here is a list of PROGRAMMED fuses for the Atmega328p AVR used in this scope clock:- Boot Flash size=512 words (BOOTSZ)- Boot Reset Vector Enabled (BOOTRST)- SPI (Serial Program downloading) enabled (SPIEN)- Preserve EEPROM memory through the Chip Erase cycle (EESAVE)- Brown-out detection level at VCC=2.7V (BODLEVEL)- Ext. Crystal Osc; Frequency >= 8.00 MHz. 16K CK/14 CK + 65 ms. (SUT_CKSEL)Moreover an archive was included with "AVRDude" as a host to upload the firmware, a firmware file and some more information. I attached this; maybe it's of some help.

author: 6CW4
author_rank: Newbie
timestamp: December 15, 2024, 04:01:26 pm
content: Thank you TurboTom - I was making an error burning the fuses - which I subsequently have corrected.It would have been more helpful if the author of the instructions had included a note on the final hex fuse values as shown by Microchip Studio as follows:BODLEVEL = 2V7RSTDISBL = [ ]DWEN = [ ]SPIEN = WDTON = [ ]EESAVE = BOOTSZ = 512W_3E00BOOTRST = CKDIV8 = [ ]CKOUT = [ ]SUT_CKSEL = EXTXOSC_8MHZ_XX_16KCK_14CK_65MSEXTENDED = 0xFD (valid)HIGH = 0xD4 (valid)LOW = 0xFF (valid)I appreciate your response.Regards,Paul K.6CW4