DC Boarduino / Menta Led question

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schnee72
 
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DC Boarduino / Menta Led question

Post by schnee72 »

I have been playing around with electronics casually for about 4 years now, the Icetube clock was my first project when it first came out. I have been able to build kits and play around with Arduino projects without really understanding what is going on. Lately my curiosity has led me to want to understand electronics better, so I have been trying to learn how to read a schematic, and I started with the DC Boarduino since I have one and the schematic is available. I figured it was simple enough that I could follow along on a breadboard, and it would greatly increase my understanding of how Arduinos work.

The Adafruit AVR sticker sure makes it easier to wire up on a breadboard!

I have been able to successfully build a working Arduino compatible on a breadboard following the DC Boarduino schematic. My question is about the led connected to d13. I do not see anywhere in the schematic where it is in any way connected to the tx or rx lines, but when programming the board with an FTDI Friend, the led flickers exactly like the rx tx leds on the FTDI friend. However my breadboard version does not exhibit this behavior. How is the led getting signal from the FTDI Friend? I also notice the Menta does the same thing, so I studied that schematic too, but I also don't see where the led is connected to the rx tx lines there either.

I was just curious if there is some indication on the schematic that somehow connects them that I am not understanding.

Thanks!
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adafruit_support_mike
 
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Re: DC Boarduino / Menta Led question

Post by adafruit_support_mike »

twolf wrote:My question is about the led connected to d13. I do not see anywhere in the schematic where it is in any way connected to the tx or rx lines, but when programming the board with an FTDI Friend, the led flickers exactly like the rx tx leds on the FTDI friend. However my breadboard version does not exhibit this behavior.
I'm a bit confused here.. the LED on something does blink when you connect it to the FTDI Friend, but the LED in the breadboard circuit shown doesn't.

What device has the LED that does blink?

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schnee72
 
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Re: DC Boarduino / Menta Led question

Post by schnee72 »

The DC Boarduino and Menta. The schematic for both boards doesn't appear to have any connection between rx/tx and the led connected to d13, yet that led blinks on both boards when being programmed.

Thanks!

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adafruit_support_mike
 
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Re: DC Boarduino / Menta Led question

Post by adafruit_support_mike »

You're right that the pin13 LED doesn't connect to either of the RX or TX pins, but digital pin 13 is also connected to the SCK pin of the ICSP header. If you're programming the chip through the SPI interface that LED will come on to let you know the transmission is happening.

I'm not sure why that LED would blink when you send information to the bootloader through the UART, but the Boarduino's bootloader is different from the plain-vanilla Arduino bootloader. There may be a software command to flash the LED during uploads.

I'll ask around and see if anyone familiar with the bootloader knows about that. The best person to ask is Ladyada, but she's at the Open Hardware Summit right now and probably doing fifteen things at once. ;-)

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Re: DC Boarduino / Menta Led question

Post by adafruit »

The pin 13 blinking is an extra-special add on we have on our 'adaboot' chips - if you burn the bootloader from the IDE it does not have this extra

http://learn.adafruit.com/arduino-tips- ... bootloader

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schnee72
 
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Re: DC Boarduino / Menta Led question

Post by schnee72 »

Thanks a lot for the explanation!

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