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Author Topic: How to connect LEDs to RX0/TX1 and still be able to flash?  (Read 545 times)
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acid
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« on: November 30, 2012, 03:07:02 pm »
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I've tried to connect 2 leds on Digital Pin0 and Digital Pin1. I know it's connected to UART RX/TX. After this connection I wasn't able to flash device - no response.
But there must be some way to isolate this LEDs from RX/TX pins during programming(except putting release buttons).

So I want to have LEDs on those pins (using all pins on Arduino UNO) and be able to program board.
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Boffin1
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« Reply #1 on: November 30, 2012, 03:19:57 pm »
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What have you got connected to all the other pins ?   more leds?
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Grumpy_Mike
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« Reply #2 on: November 30, 2012, 03:20:19 pm »
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The best way is to switch them out. That is physically disconnect them.

Alternatively you can use a buffer or a transistor to isolate them from the serial signals. They will then flash as you upload stuff but when the sketch starts running they will be fully controllable.
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acid
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« Reply #3 on: November 30, 2012, 03:21:17 pm »
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Other LEDs, SPI. The number of pins are exactly matches to requirements if I only can isolate them and use flash device without disconnecting LEDs.
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acid
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« Reply #4 on: November 30, 2012, 03:22:26 pm »
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Quote from: acid on November 30, 2012, 03:21:17 pm
Other LEDs, SPI. The number of pins are exactly matches to requirements if I only can isolate them and use flash device without disconnecting LEDs.

Could you please give me some reference values of elements?
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Boffin1
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« Reply #5 on: November 30, 2012, 03:39:37 pm »
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You can drive loads of LEDs from 3 pins with a shift register ....
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Grumpy_Mike
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« Reply #6 on: November 30, 2012, 06:12:34 pm »
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Quote from: acid on November 30, 2012, 03:21:17 pm
Other LEDs, SPI. The number of pins are exactly matches to requirements if I only can isolate them and use flash device without disconnecting LEDs.

You can't without isolating the LEDs from the serial input. As I said before you fdo this either electrically or mechanically.
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