SX28/48 clock project questions

Javalin

hello all,

Working on a project for an LED clock (not exactly rocket science - but fun) and I have questions on the selection of micro-processor - SX48 or Propeller.· 6 x 8 segment LED's arranged in either an 8 x·6 or two 8 x 3 grid's - so each 8 or 16·are pulsed at a one time.· (see - pjv and·Gunthers posts here - http://forums.parallax.com/showthread.php?p=622556)

The code has to:
1)·refresh the clock digits rapidly to maintain persistance of vision
2) wait for an input from a IR remote
3)·read the RTC (ds1307)

Can I do this using an SX48 using the timer for the LED display code, the ISR to watch for the IR remote and main line code to read the RTC?· I assume driving the LED display & waiting for a IR pulse will mean display hickups or missed IR data.

Propeller wise I am happy - one cog for each bit!

How easy is the SX48 to hand solder onto a PCB?· I can do the propeller Q44 SMT chip with care.

Kinda wanting this to be a SX project but leaning towards the Propeller for it now.

Thoughts?

Cheers,

James

Post Edited (Javalin) : 8/18/2009 3:02:46 PM GMT

JonnyMac

I've done all of the individual bits of your project with an SX28
-- time display (see the clock/timer project in the SX/B help file)
-- receiving a command from a (Sony) remote (see my January 2009 column in Nuts & Volts magazine)
-- connecting to a DS1307 is easy with SX/B I2C instructions

Soldering an SX48 can be done with care (yes, I've done it a few times). The trickiest aspect of your project, I think, is setting an ISR rate that is SIRCS friendly so that you can decode the remote input in the "background." None of this is terribly difficult, it will just take a little patience to massage together.

RobotWorkshop

The SX48 is nice since it gives you more memory, more I/O, and two 16-bit hardware timers. It isn't too hard to solder by hand. I still have a few of the SX48 OEM full kits left ($29.95 each) that are shown in the thread below:

http://forums.parallax.com/forums/default.aspx?f=7&m=194701

I also have quite a few blank PCB's which are great for mounting the SX48 processor. Just add a 4-pin header and solder the leads to the PCB and it is probably on of the best methods for using the SX48. The blank boards are now $4.95 each but drop down to $3.95 if you want 10 or more.

Another option is to use this other board but you have to make an adapter for programming since it lacks the 4-pin header. It is a very in-expensive way to use the SX48!

http://forums.parallax.com/forums/?f=5&m=366382&g=366382#m366382

If you have any interest just send me a PM.

Robert

Javalin

Hi All,

Thanks for the input...

I'll be getting a PCB made for this project.

I'll go with the Propeller option - i don't like the look of the SX48 soldering wise - but the SX28 is one pin short...!

James

Guenther Daubach

Javlin,

>> but the SX28 is one pin short...!


hmm...

The SX28 has 20 I/O pins - enough for similar projects I did in the past. If you need more free pins, you might consider using a multiplexer like the 74ACT138 which allows you to drive eight display segments by only three SX output pins.

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Greetings from Germany,

G

Javalin

Hi Gunther,

I did think of an IO expander/LED driver - but part of the fun (challenge?) of the project is to be able code the LED driver and brightness control (PWM)

Actually the more I think about it - the more I want to add - temp sensor, LDR to enable brightness control etc.... So the SX28 would be a few pins short!

Thanks for the input thou!

James