[sdiy] 7-segment LED displays with 4511 driver chip - max current?
grant at musictechnologiesgroup.com
Thu Aug 6 00:39:27 CEST 2015
Oh gawd this new format ... I'm having a hard time figuring out who said
Anyway, that's really interesting about the PG300. I imagine the
prototype on the developers bench had those attached for debugging
maybe. Or maybe they planned to use them but dropped it for price.
> On Aug 5, 2015, at 1:29 PM, Rick Jansen <rick.jansen at xs4all.nl> wrote:
> I did not intend to imply that price was the most important consideration. I merely meant to give an example of an eighties product category where a 12 MHz (1 MIPS) processor (for one example) could handle the task and the designers decided that additional support chips were not necessary.
> What's really funny is that the product I'm talking about - the Roland PG-300 - actually has no 7-segment LED in the circuit, but if you examine the firmware, you'll find that they're calculating the BCD conversion for two 7-segment displays and driving the Port A outputs for LEDs that aren't even there. I think that shows it doesn't take much CPU power if it can be wasted like this.
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