Re: Multiplexing LEDs - calculating resistor value

On Tue, 27 Jun 2006 23:32:21 GMT, Rich Grise <richgrise@xxxxxxxxxxx>
wrote:

On Tue, 27 Jun 2006 11:23:19 -0500, John Fields wrote:

On Tue, 27 Jun 2006 10:37:44 -0500, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:

Like this, actually:

+-------------------------------------------+
| 0ms |
| |<-----------2.5ms----------->| |
| ____________ ________________ |
+---->|____________|________________|--+ |
FILL ROW 1 DO OTHER STUFF | |
+--------------------------------------+ |
| |<----------2.5ms------------>| |
| ____________ ________________ |
+---->|____________|________________|---+ |
FILL ROW 2 DO OTHER STUFF | |
. |
. |
. |
| |
+---------------------------------------+ |
| 20ms |
| |<----------2.5ms------------>| |
| ____________ ________________ |
+---->|____________|________________|-------+
FILL ROW 8 DO OTHER STUFF

If the shift registers have registered outputs, i.e., if the outputs can
stay at the previous state while new data is being clocked in, and it
needs another (different) clock to transfer the new data to the output
latches, you could interleave the shifts - i.e., while row 1 is enabled
and the shift register outputs are latched, clock in row 2 data. Disable
row 1, clock the shift register output latches, and enable row 2, and so
on.

---
You don't have to disable anything, you just increment the row
decoder at the same time that you latch the new data. Read the
earlier posts and you'll see that three inputs are provided for the
shift registers: serial data, data clock, and output latch clock.
---

IOW, a given row wouldn't have to be blanked during the shift register
load time.

---
Where did you read that it does?


--
John Fields
Professional Circuit Designer
.

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