Is this correct

Thread Starter

R!f@@

Joined Apr 2, 2009
9,734
see the attached.

I am really confused here :confused: ..this is a part of my C course module 2 which I am banging my head right now. :D

Does the written paragraph matches the diagram about how the diode is really doing what it suppose to
 

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Markd77

Joined Sep 7, 2009
2,806
Sounds about right. I think the programming voltage is about 12V so the diode protects against 12V being applied to the 5V line, which is probably connected to a few other things that woudn't like it.
Or don't press the button while programming.
 

t06afre

Joined May 11, 2009
5,934
The question is do you really need a reset button in your application. If you do not need it. Then just drop it. Many newer PICs give the option to disable the reset input and use it as a standard input instead
 

BillO

Joined Nov 24, 2008
990
@t06afre

It says that RA5 is configured as an input. My guess is they are trying to show how a signal to that pin should be connected if in-circuit programming is to be allowed.
 

debjit625

Joined Apr 17, 2010
790
@t06afre
I think you missed it...
That is not a reset button.In PIC's reset happens when you give a low logic at reset pin.They are always connected form MCLR pin to Vss (GND).
 

t06afre

Joined May 11, 2009
5,934
@t06afre
I think you missed it...
That is not a reset button.In PIC's reset happens when you give a low logic at reset pin.They are always connected form MCLR pin to Vss (GND).
Yes I see it now. I did not read the schematic properly. My bad.
 

debjit625

Joined Apr 17, 2010
790
I think I missed something too...

@R!f@@
In the schematic a 10K pull down resistor has been used from MCLR pin to GND,it should not be their,it should be a pull up resistor from MCLR to Vdd (+5V).Something like this...

EDIT:
Here S1 is used to reset the mcu

Good Luck
 

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t06afre

Joined May 11, 2009
5,934
Can also add. That the programmer hate capacetive loads. On any pin used by the ICSP. And the PICKITs can not offer much "drive" for the pins used in the ISCP interface. This document will offer some more light on the problem see section
IN-CIRCUIT SERIAL PROGRAMMING™ (ICSP™) CONSIDERATIONS​
 

Thread Starter

R!f@@

Joined Apr 2, 2009
9,734
Bugger....

I destroyed two F88's.Now they are not even showing their device ID in willempro.

This is what I am paying for ????
 

BillO

Joined Nov 24, 2008
990
I think I missed something too...

@R!f@@
In the schematic a 10K pull down resistor has been used from MCLR pin to GND,it should not be their,it should be a pull up resistor from MCLR to Vdd (+5V).Something ....
No. Read what it says. That pin is defined as an input, not a reset. The circuit shown by Rifaa is fine, given that.


Edit:

Sigh!

Rifaa, the answer is yes. The schematic and the text show/say the same thing and are correct. In this case RA5 is being used as an input wherein it monitors whether or not the switch is activated or not. It is a completely valid situation and would work just fine as is shown. No changes are required. It is not supposed to be a reset circuit.
 
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debjit625

Joined Apr 17, 2010
790
BillO said:
No. Read what it says. That pin is defined as an input, not a reset. The circuit shown by Rifaa is fine, given that.
Oops I didn't read what was written on the schematic,but normally reset pin is not used for input they should be used for reset and programming...I never use them as input.Anyway you can do that...
 

thatoneguy

Joined Feb 19, 2009
6,359
Rifaa, the answer is yes. The schematic and the text show/say the same thing and are correct. In this case RA5 is being used as an input wherein it monitors whether or not the switch is activated or not. It is a completely valid situation and would work just fine as is shown. No changes are required. It is not supposed to be a reset circuit.

This is correct, but the MCLR_OFF config bit (different names in different compilers) must be set in the code so resets via MCLR going low do not occur.
 

BillO

Joined Nov 24, 2008
990
Hey Bill, I never realized u are a Mikro guy.
Yup, in all the way's that count :D.

Been at it since the Intel Z80 was just released. My first forays involved these older 8 bit CPUs. Then in the early 80's was part of a team that designed and manufactured a teleprinter (remember those?) that had a Z80 at it's core and two 8051 MCUs to run the paper punch/reader and the printer.

As it stands right now, I am trying to get a company off the ground that designs, manufactures and sells tools to support the modern MCU industry.

This is a picture of our first product. It is a programmer for the 8, 14 and 20 pin PICAXE MCUs aimed at getting rid of the rat's nest normally associated with getting them up and running. It connects to the computer with RS232 cable or a $3 USB to RS232, rather than the $20 kludge cable from the PICAXE folks and will sell for around $10 fully assembled.



Features:

Professional work flow
Allows use of unregulated wall-wart type power supply
Reduces kludge and clutter
ZIF socket reduces wear and tear on the MCU
Provides access to all signals
Quick, easy and reliable connection to the PC using a inexpensive RSR232 cable or USB to RS232 cable.
Etc...

Sorry for the plug, but there will be more coming. All based on the complaints and problems I have seen folks suffer through on the forums around the globe. We'll be addressing solutions to problems with most of the MCU families and making this easier for all. Hopefully we'll get all the operational 'business' stuff sorted out within the next 6 months and be actually able to start shipping some of this stuff.
 

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