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EXPLORER 8

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jtemples
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Re: EXPLORER 8 2018/02/12 14:38:55 (permalink)
+1 (1)
6.144 MHz x 4 PLL gives you Fosc = 24.576, which gives the desired output with REFO set for /2.
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jack@kksound
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Re: EXPLORER 8 2018/02/12 15:22:33 (permalink)
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jtemples
6.144 MHz x 4 PLL gives you Fosc = 24.576, which gives the desired output with REFO set for /2.


Yes I had forgotten about the PLL!. sad: sad
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Piero65
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Re: EXPLORER 8 2018/02/12 22:33:23 (permalink)
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I understand that using the PLL it is possible to generate a suitable clock to be sent to the DSP at 12.288 Mhz.

Let's recap, use an external quartz with 6.144 MHz frequency multiply X4 using the PLL and then before sending the output for example on RC0, divide X2 and get on this pin the clean clock without or with very little jitter to send to the DSP, it is correct ?
#23
jtemples
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Re: EXPLORER 8 2018/02/12 23:04:14 (permalink)
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use an external quartz with 6.144 MHz frequency multiply X4 using the PLL and then before sending the output for example on RC0, divide X2

 
Right.
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Piero65
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Re: EXPLORER 8 2018/02/13 06:21:59 (permalink)
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I have set up the scheme for my new hardware to be implemented with the PIC16F15356, I ask you experts if it is correct?

I have a doubt, on Explorer 8 the J26 pin 6 is free, but the applications of PCKIT 3 give it assigned to PGM (LVP) I think to be able to program the flash of the MCU, is it necessary to use this pin?
 
Is the configuration for managing SPI communication correct?
Thanks for collaboration.

 

 




#25
davekw7x
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Re: EXPLORER 8 2018/02/13 12:02:23 (permalink)
+1 (1)
infopsp
I have a doubt, on Explorer 8 the J26 pin 6 is free, but the applications of PCKIT 3 give it assigned to PGM (LVP) I think to be able to program the flash of the MCU, is it necessary to use this pin?

Older PICs had a dedicated PGM pin used for LVP.  This PIC does not use Pin 6 of the PICkit.  Leave Pin 6 of the PICkit unconnected.  I have programmed this chip and many others with no dedicated PGM pin using LVP.
 
A further note about your 12.288 MHz signal:  I hate to repeat myself, but the PPS outputs of this PIC (and others that I have tested) simply won't drive a 12.288 MHz output square wave.  Period.  [Edit]See later posts that invalidate my flat statement here.[/Edit]
 
When I use a 6 MHz crystal (using the PLL to give 24 MHz system clock) and the Reference Clock programmed for 12 MHz I get absolutely no output on the PPS-assigned CLKR pin.
 
When I program the Reference Clock to give 6 MHz output, with the only load being the 'scope probe, I measure a fall time of about 35 ns and a rise time of about 24 ns. 
 
Do the math: a half-cycle of 12.288 MHz is a little less than 40 ns.  It simply doesn't work for me.  (But I said that already.)
 
Bottom line recommendation (take it or leave it; no hard feelings): Play around with trying to get 12.288 MHz out of the PIC if you want to, but figure on spending the fifty cents for a crystal plus whatever you need for the load capacitors for your DSP chip.
 
I would be very interested if others have actual, tested experience that is contrary to my observations.  I mean, I could be wrong.  Wouldn't be the first time.  See Footnote.
 
 
Regards,

Dave
 
Footnote:
Do your own research!
---Richard Feynman
post edited by davekw7x - 2018/02/13 13:01:54

Sometimes I just can't help myself...
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Piero65
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Re: EXPLORER 8 2018/02/13 12:37:11 (permalink)
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Thanks davekw7x,
I have not yet received Explorer 8 so I did not test.
I thought using the solution proposed by Jtemples, or 6.144 MHz quartz multiplied by 4 with the PLL and then divided by 2 before sending the output to the output pin of the MCU could work .

You maintain that from your tests it does not work well.

The problem is not to save a few hundredths of components, for me it is a problem of space, I have a circular layout of 50 mm in diameter, so fewer components are more possibilities that can realize the project "quite complex" in these dimensions.

As soon as I receive Explorer, I will do some tests, just out of curiosity.
 
Ok for pin 6 PPm I will leave it unplugged.
 
Instead of the initial scheme. "I see you're a great expert" what do you think?
Are the links correct for the SPI and for the MCU debugging and on-board programming?
Thank you
#27
Jerry Messina
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Re: EXPLORER 8 2018/02/13 12:43:31 (permalink)
+2 (2)
Dave,
 
Many of the newer 8-bitters have programmable slew-rate limiting on the pins (SLRCONx) and it usually defaults to on (slow mode).  You have to turn it off to get normal IO rates.
 
Don't know if that's the case here or not...
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Piero65
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Re: EXPLORER 8 2018/02/13 12:54:51 (permalink)
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Regarding the output CON was written that the problem is the big jitter, so according to you Jerry, turning off the SLOW function the gitter is reduced and you can generate an acceptable clock signal?
It is the first time I use this MCU family so all the experiences and advice are precious.
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davekw7x
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Re: EXPLORER 8 2018/02/13 12:55:06 (permalink)
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Jerry Messina
Dave,
 
Many of the newer 8-bitters have programmable slew-rate limiting on the pins (SLRCONx)

Ahhh...
That's the ticket!
 
By clearing the SLRCON bit for the PPS-assigned output pin, rise time and fall time are something less than 10 ns, and I can get a quite decent square wave at 12 MHz (with very close to 50% duty cycle).  Even 16 MHz (using Fosc = 32 MHz and Ref Clock divide-by-2) is OK.
 
davekw7x
I could be wrong.  Wouldn't be the first time.

 
Bottom line: Very practical if you know what you are doing.  (I'm glad that I usually append my flat statements with, "I could be wrong.")
 
Thanks!
 
Regards,

Dave
post edited by davekw7x - 2018/02/13 13:13:40

Sometimes I just can't help myself...
#30
qɥb
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Re: EXPLORER 8 2018/02/13 15:21:52 (permalink)
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infopsp
Regarding the output CON was written that the problem is the big jitter, so according to you Jerry, turning off the SLOW function the gitter is reduced and you can generate an acceptable clock signal?

"Slew rate" has nothing to do with "Jitter".
 
Increased slew rate simply limits the highest frequency that can be output.
Any clock produced by NCO will have massive jitter when operating close to its own clock rate.
 
With the increased slew rate, the 6.144MHz crystal -> x4 PLL -> /2 before output should give you a good clock.
 

This forum is mis-configured so it only works correctly if you access it via https protocol.
The Microchip website links to it using http protocol. Will they ever catch on?
PicForum "it just works"
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Piero65
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Re: EXPLORER 8 2018/02/17 02:57:20 (permalink)
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Hello to all
 
I received Explorer 8 and I have to start experimenting with my software.
I do not understand this paragraph of the manual, DS40001866A-page 24.
 
I have to use an I2C communication, I understand that assigning this task to the RB1 / RB2 / RC3 / RC4 pins can power the 3.3 volt MCU without problems, if I use it for I2C other ports I have to power the 5 volt MCU, is the interpretation correct?
 
DS40001866A-page 24
These pins are configured for I 2 C logic levels. The SCLx/SDAx signals may be assigned to any of the RB1/RB2/RC3/RC4 pins. PPS
assignments to the other pins (e.g., RA5) will operate, but input logic levels will be standard TTL/ST, as selected by the INLVL register,
instead of the I 2 C specific or SMBus input buffer thresholds.
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qɥb
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Re: EXPLORER 8 2018/02/17 03:24:17 (permalink)
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infopsp
I have to use an I2C communication, I understand that assigning this task to the RB1 / RB2 / RC3 / RC4 pins can power the 3.3 volt MCU without problems,

You are using very awkward language. I assume English is not your native tongue.
I don't understand what you mean by "can power the 3.3 volt MCU without problems"
Are you saying that you want to power the PIC at 3.3 volts, and are asking if these pins will work ok?
It is unclear if you mean to use them as I2C pins, or as something else.
 
"if I use it for I2C other ports, I have to power the 5 volt MCU "
huh?
Do you mean if you try to use pins OTHER than RB1 / RB2 / RC3 / RC4 for I2C, that you have to power the PIC at 5V for the I2C to work correctly?
 
What voltage do you want to run your PIC at?
What supply voltage will you run your I2C slave chips at?
What voltage will your I2C pullups be connected to?
 

This forum is mis-configured so it only works correctly if you access it via https protocol.
The Microchip website links to it using http protocol. Will they ever catch on?
PicForum "it just works"
#33
Piero65
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Re: EXPLORER 8 2018/02/17 03:33:11 (permalink)
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Be patient, but my English is very limited.
 
All electronics operate at 3.3 volts including the MCU and including all peripherals that need to work with I2C protocol
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Piero65
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Re: EXPLORER 8 2018/03/16 08:35:10 (permalink)
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Good afternoon everybody
 
Does anyone want and time to write an assembler language program for PIC16F15356?
 
Thanks
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Jim Nickerson
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Re: EXPLORER 8 2018/03/16 08:43:11 (permalink)
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infopsp
Good afternoon everybody
 
Does anyone want and time to write an assembler language program for PIC16F15356?
 
Thanks


Are you asking if someone wants to do your homework ( assignment ) ?
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Piero65
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Re: EXPLORER 8 2018/03/16 09:24:53 (permalink)
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Thanks Jim
 
I'm looking for someone who knows PIC16F15356 and can write a program in assembler language.
The program to write is not complicated and we can privately agree on the price for writing
#37
Jim Nickerson
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Re: EXPLORER 8 2018/03/16 09:49:34 (permalink)
+1 (1)
But you did not answer my question
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Piero65
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Re: EXPLORER 8 2018/03/16 10:04:15 (permalink)
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Yes Jim,
I need to contact someone who can write a program, so I can give him a job.
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jack@kksound
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Re: EXPLORER 8 2018/03/16 10:56:02 (permalink)
+1 (1)
infopsp
Yes Jim,
I need to contact someone who can write a program, so I can give him a job.


Nicely avoided the "homework" question for a second time!Smile: Smile
#40
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