ALDL Interface

160 And 8192 Baud Aldl
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j_ds_au
Posts: 384
Joined: Sun Jan 25, 2015 4:21 pm
Location: Sydney

Re: ALDL Interface

Post by j_ds_au »

Well, the lifted capacitor can be seen to connect to pin 4, which is VCCIO, which typically gets connected to pin 20, which is VCC. So it would be normal for this node to connect to a bypass capacitor, which this appears to be. So it should be connected.

Now, your description of your LED circuit is incomplete, so I'll assume the LED is in series with the collector and the emitter connects to your 5V regulator. Now it may be that the devices on the ALDL line, including the USB interface, are sufficient to lower the "high" voltage sufficiently to switch on the transistor, which would mean it is always on. The other problem is that you don't mention a series resistor for the LED current path.

So try moving the LED to be in series with the emitter and place a series resistor (say 1k-10k, depending on your LED efficiency) in series with the collector.

Joe.
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