Junebug users - another fun little project - Electronic Circuits Projects Diagrams Free

futz · 25th November 2007, 03:55 AM

A simple POV display for Junebug 18F1320.

Quote:

A "persistence of vision display" (POV display) has only a single line of LEDs blinking on and off. The display mechanically sweeps it across a person's field of view, giving the illusion of a 2D display.

Here's a not-so-good pic of it in action. It's just printing "FUTZ" over and over. When the Junebug is moving one direction the text is correct. When it goes the other direction the text is backward. It's far from perfect, but does kind of work.

The multiplexing could probably be fine tuned to make a brighter display.

It's best to use a battery and wave the thing in a dark room, rather than risking damage with the Junebug on the USB cable. I used a 9V battery connected direct which is probably a very bad idea, but it hasn't cooked the Junebug yet. A fresh battery might be bad.

Here's a pic of my font designing notes. The code has 12 letters at present. I wanted it to be able to display JUNEBUG and FUTZ. Make your own from there.

Download source and hex file. Have fun!

EDIT: Whoops!

Found an error in the code. It shouldn't even have worked the way it was, but accidently did. The download has been updated.
Was:

Code:

main	movlw	lettF
	call	letter
	movlw	lettU
	call	letter
	movlw	lettT
	call	letter
	movlw	lettZ
	call	letter
	return

Obviously the last line should have been:

Code:

	goto	main

blueroomelectronics · 25th November 2007, 06:29 AM

That's awesome

Love it.
A $1 6V camera battery might be kinder to the PICs.
Some NiMH 9V are only 7.2V and a simple 1N4001 diode would put it closer to slightly abused specs. Original PICs were designed for 7V the 1650

blueroomelectronics · 26th November 2007, 04:27 PM

Futz have you ever worked with iButtons / 1Wire devices?

futz · 26th November 2007, 04:31 PM

Quote:

Originally Posted by blueroomelectronics

Futz have you ever worked with iButtons / 1Wire devices?

Nope. A few years back I tried to get that working and had no success. It was just around when I lost interest in mcu's and electronics for a few years. Now that I'm tinkering with this stuff again I plan to try again very soon.

blueroomelectronics · 26th November 2007, 05:31 PM

That little connector under the reset button was designed with the DS18S20 in mind, even the pullup is there.
Kyle-s4H did some iButton programming for the Firefly.

Here's another interesting project that should be easy to do.
http://www.jdm.homepage.dk/solarpic.htm

Or this
http://www.sixca.com/eng/articles/remote/index.html
Note: the 12F629 doesn't need the crystal for this application.

futz · 26th November 2007, 10:07 PM

Quote:

Originally Posted by blueroomelectronics

That little connector under the reset button was designed with the DS18S20 in mind, even the pullup is there.

DS18B20 close enough? I have one coming in my Spark Fun order.

I've got both data sheets here and they look real similar.

I need to get SPI working on the Junebug too, but that's almost as easy as asynchronous serial. I designed and built several 7-seg 4-digit LED displays a while back that use the MAX7219 chips.

blueroomelectronics · 26th November 2007, 10:25 PM

There is no hardware SPI on the 18F1320 so it would be all bit banged. The DS18B20 and 18S20 are similar, I can't recall the differences off the top of my head. There is also a PAR version.
Of course you could use a thermistor in the same socket.

futz · 26th November 2007, 11:13 PM

Quote:

Originally Posted by blueroomelectronics

There is no hardware SPI on the 18F1320 so it would be all bit banged.

I think it does. It's called Synchronous Mode. Looking at the datasheet I see master and slave synchronous modes available.

Quote:

Of course you could use a thermistor in the same socket.

I have one of those too.

blueroomelectronics · 26th November 2007, 11:42 PM

I don't see a SSP or MSSP in the datasheet. There is a synchronus serial port but that's not SPI, that really fast serial.

futz · 26th November 2007, 11:48 PM

Quote:

Originally Posted by blueroomelectronics

I don't see a SSP or MSSP in the datasheet. There is a synchronus serial port but that's not SPI, that really fast serial.

Maybe that's why I had trouble making it work before.

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25th November 2007, 06:29 AM	(permalink)
blueroomelectronics	That's awesome Love it. A $1 6V camera battery might be kinder to the PICs. Some NiMH 9V are only 7.2V and a simple 1N4001 diode would put it closer to slightly abused specs. Original PICs were designed for 7V the 1650 __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

26th November 2007, 04:27 PM	(permalink)
blueroomelectronics	Futz have you ever worked with iButtons / 1Wire devices? __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

26th November 2007, 05:31 PM	(permalink)
blueroomelectronics	That little connector under the reset button was designed with the DS18S20 in mind, even the pullup is there. Kyle-s4H did some iButton programming for the Firefly. Here's another interesting project that should be easy to do. http://www.jdm.homepage.dk/solarpic.htm Or this http://www.sixca.com/eng/articles/remote/index.html Note: the 12F629 doesn't need the crystal for this application. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com Last edited by blueroomelectronics; 26th November 2007 at 06:18 PM.

26th November 2007, 10:25 PM	(permalink)
blueroomelectronics	There is no hardware SPI on the 18F1320 so it would be all bit banged. The DS18B20 and 18S20 are similar, I can't recall the differences off the top of my head. There is also a PAR version. Of course you could use a thermistor in the same socket. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

26th November 2007, 11:42 PM	(permalink)
blueroomelectronics	I don't see a SSP or MSSP in the datasheet. There is a synchronus serial port but that's not SPI, that really fast serial. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com