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Do I really need to use the /SS pin for SPI between two ATMEGAs?
strontiumdog wrote: The answer is MAYBE.   Master - Does not NEED to use /SS, its just an IO you can use any pin, or none, and the Master will send what you want. However you...
Tuesday, 16 July 2019 - 23:57
Generating a 4Mhz square wave/clock for the ATMEGA644P
digitalDan wrote: Vpp = 52.8 V  !!?!?!? Is this just a case of using a 1:1 probe and the scope thinks it's 10:1 (or a 10:1 and the scope thinks it's 100:1)? If it really is...
Wednesday, 10 July 2019 - 23:37
Generating a 4Mhz square wave/clock for the ATMEGA644P
avr-mike wrote: unebonnevie wrote: At 4.03Mhz!  0.3Mhz extra.  Probably I can set OCR0B to 1 to get rid of the extra 0.03Mhz.   Your clock is probably running at 8...
Wednesday, 10 July 2019 - 21:22
Generating a 4Mhz square wave/clock for the ATMEGA644P
avr-mike wrote: It sounds like you have an 8MHz clock and want to generate a 4MHz output.  For this, you do not need PWM. Set up a timer to run at full speed in Clear Timer...
Wednesday, 10 July 2019 - 20:37
Generating a 4Mhz square wave/clock for the ATMEGA644P
avrcandies wrote: The nice thing about a divider is it will give you "exactly" 50% duty, regardless of the input duty cycle  (neglecting any slight variations, and time...
Wednesday, 10 July 2019 - 19:16
Generating a 4Mhz square wave/clock for the ATMEGA644P
joeymorin wrote: Or, if the app can live with it, divide the system clock by two via CLKPR   Not familiar with the CLKPR option.  Found the post  https://www....
Tuesday, 9 July 2019 - 14:11
Generating a 4Mhz square wave/clock for the ATMEGA644P
ka7ehk wrote: If it needs to be a true PWM (that is, varying duty cycle), then no, you cannot from a Mega644. You need something that has a clock, significantly higher than 4MHZ,...
Tuesday, 9 July 2019 - 02:20
I/O operating voltages between two ATMEGAs
Thanks, all.  A 74LVC245 should help.  " Inputs can be driven from either 3.3 V or 5 V devices. When disabled, up to 5.5 V can be applied to the outputs. These features...
Friday, 14 June 2019 - 06:09
I/O operating voltages between two ATMEGAs
tpappano wrote:The 3.3V should be OK with 5V input, that is, no need to level shifting or anything? Why should it be ok? (It is not) A read of the data sheet would be a good...
Wednesday, 12 June 2019 - 23:36
Looking for the below specific jump wires
Hi all,   Thanks for the answers, but please look at the OP with the image I attached.  These jumper wires are quite special, not the ones you recommended, which I...
Friday, 7 June 2019 - 04:17
Attiny lock bits to prevent firmware from being read
clawson wrote:You can set those bits but I can pay $500 and get them unlocked so don't trust your entire IPR to $500's worth of silliness. . Besides in just 2K of code I'd suggest...
Monday, 22 October 2018 - 01:19
Low voltage on old CPU, the MC68000 and MC68008 CPUs
I decided to scale down a bit and use the Z80, instead of MC68000.  I get 4.5V between as Vcc input via a USB power source.  I wired up a free-running circuit and the...
Saturday, 12 May 2018 - 23:38

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