Serout to LEDs

[wob_b]

Hi, I read about doing this in a book... And i'm sure there are loads of threads about it - I have had a look, and couldnt see anything.
I'm looking for chip I can send a serial output, from a PICAXE chip, to and it converts the 8 bits I output into 8 digital outputs. What's its called?

Thank you
Rob

 

[BeanieBots]

Serial to parallel (converter).

 

[eclectic]

Rob, also try a search using
74HC595

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[hippy]

If you want to convert 'genuine serial' ( as sent by SEROUT ) or do this all with only a single data line you will need something more than a shift register. This task would normally be accomplished by the receive side of a UART, the easiest solution here is to use another PICAXE.

 

[westaust55]

If you have a 28X1 or 40X1, you can use the SHIFTOUT command (needs 2 lines) plus a separate line for latch to output serially to a shift register such as the 74HC595.

The actual SEROUT command will as hippy states, require something more complex as the receiving chip/circuit.

You really need to explain a little more about your objectives.

 

[inglewoodpete]

If your application can tolerate the data rippling past each output bit, you can use a 74LS164 and save on the "Output Latch" line necessary for the 595. An example that would normally tolerate the data rippling through would be a series of LEDs connected to the outputs.

Refer to the datasheets for 74HC595 and 74LS164 to see the differences.

 

[wob_b]

Thanks for the replies: in response to westaust55's comment about my objectives; when I wrote it, it was just curiosity, however, this changed today...

A friend has asked me to help them in a project they're working on - they need help with the electronics of a "Daft Punk Helmet":

http://uk.youtube.com/watch?v=NyBHb3gfr2Q

Yes a huge feet I know, an i doubt I will be able to recreate it exactly. I'm going to start, forgetting about the colour changes, just controlling an array of LEDs that size from 1 picaxe (Effectively a LCD display with LEDs, although it would be nice to put "pictures" up there aswell). If it wasn't for the cost, id go straight for the main picaxe giving serial outputs to a number of secondary picaxe's, which in turn light LEDs. This is why a cheaper chip that can do the job of the secondary chips would be great. Or even the signal goes from primary chip, to secondary picaxe's, and from there to another.

Now i've written it down, it seems even crazier. But a challenge is always fun. What would anyone say is the best solution to controlling a massive array of LEDs?

Thanks,

 

[hippy]

An 8x8 I2C controlled LED multiplexor is probably the easiest route to controlling multiple LED's. You'll probably also want I2C Eeprom or other off-PICAXE memory to store patterns to display.

 

[premelec]

Take a look at the TLC5922 data sheet at TI.com - a 16 LED driver - National also has something similar - there are more drivers appearing as more LEDs get cheaper!

[LP3936 LP3954 from national.com are not quite what I recall but interesting... ]