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I need some help with the LED Ladybird

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2010 - » Archive through 07 November, 2014 » I need some help with the LED Ladybird « Previous Next »

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guin5ter
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Posted on Friday, 17 October, 2014 - 05:13 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi all

Has anyone tried to build this unit ?

I can't manage SMD's - eyesight not up to it - so I want to construct it (double size) on a piece of MDF with a DIL PIC16F88 soldered to Veroboard.

I would like help with the following :

(i) Does the software work OK (both the *.hex and *.asm) ?

(ii) Will my Vellerman K8048 plus PicProg2009 program the PIC16F88 ?

Regards
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bowden_p
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Posted on Saturday, 18 October, 2014 - 05:12 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Dave,
Welcome to the CZ!! I hope we can help with your questions.

I haven't built this project, but I have had a look at the spec. for the PIC16LF88 to compare with your proposed PIC16F88 version. Or rather, I tried to. Microchip don't have a spec. for the "LF" version!!

To answer your point (i) :-
The usual difference is that an "LF" version works with a lower Vdd supply voltage than its straight "F" sister chip, resulting in lower power operation :-
i.e. 1.8V - 3.6V for the "LF",
and 2.3V - 5.5V for the "F".

I see that the PIC16F88 spec. claims it will work with Vdd of 2.0V - 5.5V, ( Current spec. issue "D"), so working with a fresh 3v lithium cell should be ok. As the cell voltage declines with use, and its internal impedance rises, you may find the project will require a new cell more often than with the "LF" version. It doesn't help not having a spec!! 2 x AA cells will be ok too.

An alternative might be to run the project from 3 x AA cells, so guaranteeing functionality of the "F" PIC. As you intend it make a twice size version, these could be easily held in a battery holder underneath the MDF base. However, this design doesn't include the usual current limiting resistors for the LED's, so this would definitely not be a good idea! A PWM scheme is used instead, with the output resistance of the PIC contributing to the current limiting.

So, I can't see why the software shouldn't work with the "F" version. Select the "F" PIC in your programming software, look in the "asm" file and edit any reference to the "LF" version to just "F", and re-compile.

I can't help with point (ii) as I don't know this hardware/software. Somewhere in the documentation there should be a reference as to what chips it can programme. As the PIC16F88 is quite an old design, I imagine it will cover this chip.

With regards, Paul.
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bowden_p
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Posted on Saturday, 18 October, 2014 - 05:56 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Dave,
Your programmer will take the PIC16F88 package in the 18-pin socket. From the Velleman site the User Manual for the K8048 shows it uses the MPASMWIN.EXE compiler. Select the PIC16F88 in the centre right window :- "Processor", for compiling.

My apologies if you already know this!
My guess is that the hex file will program and run on the "F" device, as supplied.

With regards, Paul.
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bowden_p
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Posted on Saturday, 18 October, 2014 - 10:43 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Steve,
Just looked at the asm file - it is compiled for the PIC16F88, so you definitely can use the hex file for your chip.

With regards, Paul.
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guin5ter
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Posted on Sunday, 19 October, 2014 - 07:49 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Paul

Many thanks for your very comprehensive help.

I am opting for x2 AA cells to avoid the need for current limiting resistors.

All I need now is to figure out how to squeeze 22 led's, a PIC and associated components onto the piece of stripboard.

Regards Dave
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bowden_p
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Posted on Monday, 20 October, 2014 - 01:12 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi Steve,
You're welcome - sorry my posts are a bit rambling, but they were posted as I explored more.

I wish you every success with your version - post a photo when complete!

With regards, Paul.
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arw
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Posted on Monday, 20 October, 2014 - 11:53 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

PS @ Dave due to some quirks on the legacy CZ software, to start an entirely new thread the link at the foot of the main forum page is the one to use, otherwise you'll start a sub thread off an existing one. Which is why I moved your post to the main forum. Sorry 'bout that, but we got there in the end :-)

-- Alan W
Alan W -- EPE

More online resources at www.epemag.net
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guin5ter
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Posted on Wednesday, 22 October, 2014 - 04:45 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi

To Alan W - I will do as you say if I start a new thread. Thanks for the info.

To Paul B - I'll post a photo of my giant Ladybird when it is complete.

Regards Dave B

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